1. The car didn’t want to run when it was cold, it would chug and stall unless I kept my foot on the gas. This was for the first few minutes until it warmed up. This was due to having absolutely no idle speed control.
2. The car ran like absolute garbage during this time.
3. It started stalling at traffic lights.
4. I was still only getting 1.2 bar on the boost gauge

I guess that’s four. We’ll address these issues in order.

For starters it was clear that I had an issue with the idle speed control circuit, as in, it just wasn’t doing a darn thing. The base Idle Speed in this car has a mechanical setpoint. The idle speed is then adjusted by an air bypass valve controlled by a module outside the realm and knowledge of the ECU. This system increases airflow into the system ( and hence raises the idle speed) under certain conditions.

The inputs to the control module are:

1. +12v Power (duh)
2. Coolant Temperature
3. AC Compressor active signal
4. Instrument cluster speed signal
5. Radiator Cooling fan active signal
6. Idle mode signal
7. and probably some others I’m forgetting.

The system will adjust the idle speed a little or a lot depending on those various inputs. You’ll note it doesn’t take an RPM reference speed to try to achieve a target or anything. It assumes a known baseline and simple adds some number of volts to the air bypass valve according to some calculatio ( x number of volts = y rpms). Reading on forums, folks say the first thing to check are the resistors in the unit, as there’s one in particular that goes bad and messes up the entire works.

So, I opened it up and, yeah that looks pretty toasted. (Don’t mind the torn ribbon cable, that disintegrated on me pretty quickly, but was intact when I started.)

I took an inventory of all the capacitors inside as well, figuring I might was well replace them too.

And here you can see a nice new resistor with some pin headers to keep things simple. Also note the new red capacitor in the lower part of the board. One thing I did learn when recapping this board is that, the traces on this thing are super duper fragile, and I ended up completely nerfing a couple pads and traces along the way. So there are currently about 4 different bodge wires and solder bridges. Not my best work, and when I lifted my 3rd pad I was starting to have a serious bout of “Did I forget how to solder?”

Anyway, excited about my handy work, I plugged it, crossed my fingers…and NOTHING. It still wasn’t doing anything. I was devastated. I kept driving the car as it had been pressed into service as my Daily Driver at this point. After some number of months of chugging and sputtering through the neighborhood first thing in the morning, I found another of the exact part number: 443.907.393P on ebay about $100. I ordered it, because I was 100% convinced I screwed up the rebuild with all the lifted traces and what not.

A note on Audi Part Numbers. That little P suffix on that part number is critical. These modules were used across the Audi / VW line in anything with the Bosch CIS fuel injection system, but they were VERY application specific, because different systems had different accessories and different loads which needed different amounts of voltage supplied to the valve under different conditions — all denoted by the suffix on the part number.

Anyway, do you want to know what happened when I plugged the new one it? Yep you guessed it. Nothing. This meant I’d been chasing my tail for months on this and the problem was elsewhere. So, I went back to the drawing board and started testing all the inputs to the control module AGAIN.

I found that the throttle position switch wasn’t actually working. This switch comes in the form of a little black box. The armature from the throttle plate goes in one side. When you’re foot is off the gas, it closes one set of contacts with tells the computer “We’re in idle mode!”, when you’re flooring it to get out onto the highway, it closes another set of contacts which says “We’re going for it Hoss!”. So basically, the computer has three operating environments. Idle, driving, and YAHOO!

Well, I found it was never sending the idle signal. I decided to open up the box to check it out, figuring it would be a bad solder joint or dirty contacts or something. It’s a very simple device, so shouldn’t have been too hard to diagnose and repair.

Friends, when I opened the box and found there was no circuitry inside for the idle circuit I may have lost my cool a little. Doing some number of hours of research on the finer points of Bosch part numbers and their automotive applications, I found that the part number on my little box actually pointed to a ’77-’78 Porsche 911 — which didn’t have the idle circuit.

I ALSO learned that these haven’t been available for a decade or more. I eventually found a used one, with the correct Bosch part number, listed for an ’85 Porsche 944 — Like I said, they used this system on everything for decades.

After installing it, I had to adjust my idle baseline. In Idle mode, the computer advances the ignition timing and adds a ton of air (via the Idle Control) system to keep the idle speed up. So *that* part was working at least — but that’s all controlled by the ECU. Idle speed control, however STILL wasn’t working. Okay. Got to keep going.

It was at this point I found this guy:

A cruddy looking temp sensor, but like the end is soldered on, so it must be fine right? No. No it was not. It turns out the core of the sensor was loose and when I would press on it with the multimeter to read the value, it made contact and was fine. Remove the probe and it would make no contact internally. Well, measuring this with the engine running, and pressing on it in just the right way, the Idle control circuit sprung to life! I jiggled the sensor, idle speed contol stopped. I pressed on the sensor, Idle speed control resumed….

$8 later and little wiring work later things looked and worked a lot better!

Now, please dear reader, forgive me at this point for not checking the temp sensor more closely. The fact of the matter is, this car has more temperature switches and sensors than I’ve ever seen on a car, and it’s not always clear which one goes to which. After two years however, I now have a decent understanding of all the ways this car cares about temperature.

1. A temp sensor for the ECU
2. A temp sensor for the Idle Circuit
3. A temp sensor for the gauge on the dash
4. A temp sensor for the warning light on the dash.
5. A dual stage temp switch in the radiator for the fan
6. A temp switch in the thermostat housing for the after-run fan
7. A temp switch under the fuel injectors for the injector cooling fan.

Anyway, at this point, I’ve verified they’re all working! AND I HAVE IDLE SPEED CONTROL. I had to readjust my idle baseline again, but that’s fine because, it idles when it’s cold. And the idle goes up when the AC compressor kicks on. And the idle stays high when coasting to stop (kinda, more on that later). And the idle kicks up when the 500W cooling fan kicks on. Amazing.

At this point, it still doesn’t run great when cold, and it started stalling at stop lights, and I’m still not getting ECU modulated boost, only mechanical waste gate level boost. I’ll cover these in Part 2!

These two behaviors pointed to a couple things, first the manual told me that the light coming on under acceleration is the computer telling me that it can’t adjust the timing anymore, even though it really wants to. Ignition timing advance/retard is a critical piece of functionality in any car. It ensures that the spark occurs at the the right time to get maximum bang for the buck from the air/fuel mixture. As the burn happens at a constant rate and is not instant, the spark needs to happen earlier at high engine speeds than it does at low rpm. This light says, “I can’t retard the timing anymore”. This can lead to something called pre-detonation or pinging, this is when the spark happens too early, and the flame front of combustion starts interfering with still compressing air/fuel mixture. In extreme cases, especially in turbo charged applications, this can very quickly lead to a very broken engine. Like, broken bits inside kind of broken. To be clear, during the months of driving, I’d never heard any pinging or knocking, so hadn’t been too worried about the above happening.

Ever car sold in the US starting with the 1994 model year, complies with the federally mandated OBD-II standard. That is On Board Diagnostics 2. This ensures a common communications and reporting interface to talk to the car’s computer. This is how we read out error codes from the computer to know why the CEL is illuminated in the dash. I can use the same tool to read the engine codes from a 1994 Chevy Cavalier as I can from a 2024 Lamborghini. The situation before 1994 is somewhat more fraught. Pre 1994, there was no unifying standard. Every manufacturer had their own way of doing things. Various special tools and procedures existed in order to try and figure out what the computer perceived to be wrong. For a 1988 Audi the procedure is as follows:

1) Bring the engine to operating temperature
2) Achieve full throttle at 1.0 bar and exceed 3500 rpm once.
3) DO NOT TURN OFF CAR
4) Open the hood, remove the fuse panel cover
5) Jam a fuse in the top of the fuel pump relay for three seconds and remove
6) Count the blink pattern of the CEL on the dash.

How intuitive.

Not hard, but not something you’d be able to do without the very specific specialized knowledge to do so. Again every electronic engine management system before 1994 had an unknowable and undiscoverable (without the shop manual) diagnostic procedure of this nature.

Doing this, we got the blink code of 2-1-4-2, which indicates: “Knock sensor #1 Open or short circuit, Defective sensor Check sensor and wiring” Sounds easy enough. Looking up the knock sensor for this car, I found VAG used it on everything from the ’86 5000 up through ’07 Touaregs! In other-words, cheap and readily available. I ordered one for $12 and waited for it to arrive.

After some weeks wait, the part arrived (I didn’t see the need to pay $60 to get one from Autozone immediated, the car was functioning file otherwise). I then engaged in an embarrassing 10 minutes of, where the heck even is this thing on the engine? Turns out the OEM style and the modern style are VERY different looking. I ended up finding the harness connector in the back of engine bay and following the wire to find the sensor. The old sensor screwed in with an integral threaded post.

The new one, just has a hole in the middle for a bolt.

It didn’t come with a bolt.

Thankfully, I had something of appropriate thread and length in the bolt bucket and so was able to install the new sensor. I went for a test drive. I stuck my foot in the gas, .9 bar, CEL light. Son-of-a….

I drive it around a bit to warm it up and as per the procedure above. After jamming the fuse in the relay, I got the following code: 2-3-2-2 “Inlet air temp Open or short circuit” Hey, at least that’s different!

It was about here that I learned, this computer is so primitive, it can only track one error code at a time. The Inlet air temp sensor is right at the top of the Intercooler inlet, I touched the wiring harness and it simply fell off the sensor.

Problem identified! After some not-as-quick-as-I’d-have-liked wiring repair, I took it for another test drive. I observed the following:

1) no CEL at .9 bar.
2) At 4500 RPM is kept pulling all the way to redline. WOW!
3) Still not going above 1.2 bar.

Let’s talk about that 1.2 bar for a moment. This is limit of the mechanical waste gate. The wastegate is the valve which controls the amount of boost in the system. This car should go up to 1.4 bar. That extra .2 bar is achieved by the ECU manipulating the wastegate to keep more boost in. So, this indicates there is still a fault in the system somewhere which is preventing the ecu from modulating boost pressure.

Going through the code reading procedure again, I get 4-4-4-4: “No faults”. Next step is going through the static test procedures. This is similar a process of jamming fuses in places to make things actuate and observe the behavior. That’s an upcoming work session, but for right now the car is running great with good smooth power all the way to red line — once it’s warmed up (The non-functional idle-speed compensation system is another saga, which is still in on-going.)

Once the new cluster showed up, I immediately installed in into the car to make sure it worked, or at least take stock of the parts that didn’t. I turned the key on and I was immediately greeted with “bar: 0.3” in the center LCD, success!

I turned the lights on, and there was but a dim glow from the upper right corner. I started the car, everything just seemed to work, I went around the block, and counted 3/10 of a mile. Success!. I decided to run with this new cluster for a few days until I could get to replacing light bulbs, and decide what I wanted to do with regards to the odometer reading.

Of course, the next day, the odometer stopped counting at about 18 miles. Not unexpected, but an occurrence which, at this point, was very discouraging. At least I had the new gear set on hand.

On a day when I had ample time to mess with it, I engaged in major cluster surgery.

I swapped all the bulbs from the old cluster to the new, I swapped the rebuilt LCD control board in, I swapped the new capacitors into the speedo/odo control board. I disassembled the speedo/odo to set the mileage.

The car showed, 189k when I got it, I’d been keeping my gas receipts, so I knew how many gallons I’d burned through. Taking the number of gallons times the EPA avg fuel economy, gave me 2200 miles. So, I set the odometer to 191k — good enough for a 35 year old car. I, of course, also installed the new odometer gear set, I even spun things with a long small screwdriver to be sure nothing was hanging up.

With everything buttoned up, I reinstalled the cluster into the car and took it for a test drive. I got 2/10 of a mile before it stopped counting. In addition the speedometer wasn’t working right, it would barely register over 20mph. I was beside myself. I took everything apart again, using my long screwdriver to move the gears inside the odometer, I could tell something was hung up, I pushed a bit and things started moving again. In a burst of optimism, I put the cluster back in the car and went around the block. 1/10 of a mile before it stopped counting.

I took a deep breath and pulled the cluster out again. I disassembled the cluster AGAIN, and pulled the speedo/odo pod out AGAIN. I grabbed my bag of alligator clips and jumper wires along with a 9v battery in order to simulate the input the speed sensor would send to the cluster in attempt to observe what happens. (I was so frustrated at this point, I didn’t think to grab a picture of this process). I was able to un-jam the works again with my trusty screwdriver, hooked up the wires and started simulating input (this is accomplished by making and breaking contact to ground very fast in the hopes of generating a square wave signal. I observed the motor doing it’s step, step, step, twitch, twitch, twitch. I un-jammed it manually, and simulated input. It would step properly for a bit, then start twitching, I would unjam it. I continued this for a while before I took the pod apart again to check for debris, to make sure nothing was getting hung up…nothing.

Back together and simulate. At some point it seemed to be getting further between jam-ups. When I hit a full mile on the trip meter, I started having some hope. When I got it to five miles, I said, okay, good enough, lets put it back in the car. I also cleaned and added a little lubrication to the speedo needle shaft, where it passes through a nut which holds the hole works together. That clear the hangup there…thank goodness.

On the next day’s journey, it counted 1/10, 2/20, a mile and beyond. All the way to 22 miles….and stopped. I recalled, that when simulating input on the bench, resetting the trip meter sometimes had an effect. That action seems to jostle things just enough to sometimes shake things loose. Indeed, I reset and it and it started counting again. It got to some number of miles over the next few days. I stopped and topped up the tank and reset the trip meter. I was determined to finally be able to calculate my gas mileage. The Board computer, which displays through the center LCD was showing something silly like 60 mpg, which was clearly wrong (Will address this in another post). As I type this, the tank is near empty and the trip meter shows 257 miles. Honestly, I’m a little afraid to reset the trip meter, but I imagine whatever it was getting hung up on has clearanced itself.

So that’s it, it took 10 months of ownership, about $200, countless hours worth of poking and prodding, and countless remove/replace cycles of the cluster to get everything to work as it should. I must really like this car, because the time and heartache investment in just the instrument cluster, is objectively not worth it.

Note: This work was finished in at the end of December. It’s now beginning of April and everything has just been OK with the cluster! We’ve counted almost 2000 miles without missing a beat!

The procedure to pull the cluster couldn’t be more straight forward.
1) Remove the horn pad (just pull)
2) Remove the nut holding the wheel to the column, and pull the wheel off.
3) Loosen the clamp which hold the Multi-function switch to the column, and slide off.
4) remove two small screws from the cluster, pull it out and unplug 3 electrical connectors.

I knew I was in trouble when, as I completed Step 2 , I was showered with a dozen tiny ball bearings. You’ll note, that “pick up ball bearings and try to insert them into their mangled nylon carrier” is NOT in listed in the procedure above.

Having a suddenly acquired a new side-quest, I started searching the floor and by some miracle, was actually able to find all but 1 of them. Turning my attention to the mangled carrier, I was able to kind of bend it mostly back into shape, and pop the bearings into their spots. This bearing, sits just inside the column housing around the steering shaft, behind the steering wheel, offering support and smooth operation. Without it, there is a disconcerting amount of up/down left/right play in the wheel, along with unhappy metal scraping sounds when the wheel is turned. Thankfully, the bearing carrier seated well in the column. It seated so well, I was unable to remove it again, which make me wonder what kinds of abuse this poor car suffered before it came to me. Regardless, with this intermediate crisis out of the way, I proceeded down the list.

Once the cluster was removed, It was immediately obvious that I’d acquired another side quest. The contacts between the various bulbs and needles and the electrical connectors, consist of very very thin strips of copper, embedded in a fragile plastic sheet. The plastic contact mat was torn in several places, preventing signals from getting to where they needed to be.

Repairing a broken circuit trace is generally a straightforward operation. You can either bridge the trace with solder if it’s a small crack, or run a bodge wire to give a new electrical path. This is a not-uncommon occurrence when working with old computers in general. Unfortunately, given the light plastic nature of the “board”, it would simply melt and shrink when the soldering iron would come near it, so it was VERY challenging to try and bridge the broken the traces, but I persevered and managed to make some repairs which showed that I had restored electrical continuity.

So, with repaired traces and all new light bulbs, I plugged it in, turned the ignition switch to “on” and learned that while the fuel gauge came back to life, the center LCD did not. Bummer. I clicked the lights on to be sure all the new bulbs worked and several bulbs in the cluster EXPLODED.

Sigh. So, I took it apart, cleaned out all the broken glass, and replaced the exploded bulbs and the various newly burnt out ones, with old working ones. After getting everything back together I tried again. Success, illumination and no explosions!

All of the above happened while I was working on the breaks and the power steering pump. Once I started driving the car, a few things became apparent. First I really wanted a boost gauge in order to know what the turbo was doing. The boost gauge is a digital readout, provided by the non-functional center LCD. Second, the check engine light worked, I know because it would light up every time I accelerated. Third, by some miracle, the odometer still worked (this is a known weak spot for gauges made by VDO from this era) — at least for 36 miles, when it stopped counting miles.

That the odometer broke wasn’t too surprising or upsetting. There is a set of nylon gears which interfaces between a stepper motor and the gears behind the numbers. The gears simply crack and fall apart due to age. This is such a big problem for every 80’s and 90’s European car with a VDO speedometer, that new gear sets are readily available for a few bucks. I removed the cluster (again) and fully disassembled it. I found no cracks in the gears, which perplexed me. As I opened things up, I was hit the face with a vaguely fishy smell, which is indicative of leaking electrolytic capacitors. Dead/leaking caps can absolutely cause circuitry to just not work, so I took inventory and placed a Digi-Key order. I also ordered a new gear set. I put everything back together and reinstalled it, so I could continue to drive the car.

Once all the parts came, I made quick work of the capacitors and the gear replacement. I did find a missing tooth on the old gear, which helped explain the stoppage.

I put it all back together and turned the key on, but I still had no center LCD – at this point I figured it was just a bad LCD panel, and I’d have to source a new one. I started the car and drive down the street. It through clicked 2/10 of a mile and stopped counting again.

So, I took everything apart again and found a small bit of debris in the gear track. With that cleaned out, I figured I’d solved it and put it all back together and reinstall it into the car. 1/10 of mile and it stopped. At this point, I was beyond frustrated and was questioning if an oily rag and a match might be a better solution to this issue. I took everything apart AGAIN and decided to test the circuitry itself on the control board for the speedo/odo. I knew it was getting signal from the speed sensor, as the speedemeter worked without fail.

So, on the bench, I simulated input to the board. I measured voltages coming out of the IC chip and everything checked out, the motor was simply not turning when it received voltage. It’s at this point I noted, that the motor, wasn’t sitting flush to the board, a very small amount of wiggling and it popped off the board all together — except the pins which are used to solder the motor to the board, which were still soldered in place on the board.

It turns out, this is possibly one of the worst designs I’ve ever seen. The windings of the motor, which are about as thin as a hair, are soldered to a metal pin, which is held in place with nothing but friction to the plastic housing. The other end of the pin is soldered to the circuit board. That’s it, there is no other mechanical attachment of the motor to the board, so with any movement or manipulation of the board, you risk damaging the connection from the windings to the pins, irreparably damaging it.

I mentioned above that tons of cars with VDO gauges have an issue with the nylon gears. Unfortunately, almost no other car uses this particular motor and control board. It seems only 86-88 Audi 5000 Quattros and similar year Volvo 740s used it. I’m guessing that VDO realized they had a turkey of a design on their hands as all other cars from this era that use VDO gauges seem to have a far more sane motor/board interface.

This also means that it’s incredibly hard to find a replacement. There are no markings on the motor itself, so I needed a donor cluster from one of the above cars. The only thing I was finding on E-bay was a cluster for $450 out of Latvia. Considering the dead center LCD, I needed a donor cluster anyway. But $450 seemed a little too steep, so I kept periodically checking E-bay, hoping for a cheaper option.

October 29th: It was a seemingly normal Saturday evening, two days before Halloween. I did something which many people so on such a Saturday evening, and attended a Halloween Party. On my way home from said party, at around 2am Sunday morning, the alternator belt in the Audi started screeching and was having a hard time catching. This shouldn’t be happening as the belt and the tensioner bolt were all new. It was only a couple miles home, so I vowed to check and tighten belt in the morning. Then, a mere two blocks from home, the Battery light Came on, the Voltage check circuit lit up and the lights got dim. Uh-oh. I was already fighting a weird issue with the battery where it wouldn’t reliably hold a charge, leading to random hard/no start issues. As such, I didn’t know how long it could run only on battery power. As we’ve seen in various Star Trek episodes, I took the last resort of diverting power from Life Support, i.e. I shut down the ventilation fan, and the rear defroster. I made it the two blocks home back to Space Dock, with some extra dim headlights.

The next day, we took a family walk and found the alternator belt on the ground in front of a neighbors house, chewed up and crispy. Not a pretty sight.

Deciding that I couldn’t put that one back on the car, I found that I actually had a spare alternator belt in the garage, score! I also found that the brand new whacky looking adjustment bolt had gone missing.

Sadly, the threads which used to inhabit the ear of the alternator, where mostly missing as well. I found a nut and bolt to substitute, got the new belt tensioned up, then had to re-tension the AC compressor belt as well — The Audi has this very bizarre intermediate adjustment bar that goes between the two and influences the tension on both, for some reason. I haven’t looked up the proper procedure for tensioning all the belts as I’m sure its an irritating 15 step process that involves at least two special tools. I have a 13 mm socket and a long screwdriver — good enough.

October 30th: With a repaired car, we made a trip to South Seattle to an architectural thrift shop, to pickup some period correct light fixtures for the Mid-century house we currently call home as well a matching door for one of the bedrooms — and yes the Audi can fit an entire door in the back with the seats down. We get to the place, a good 35 minute drive and find what we need. I go to get the Audi to pull it into a loading bay and — there’s not enough juice in the battery to start the car (again). Thankfully, Lisa bought a little booster box a couple weeks back when this started happening intermittently. With the car started, I pulled it around, left it running, we loaded it up and took off for home.

About 1/2 way home, I got a scary looking alert in the Check Module. A temperature symbol with a big red triangle. The second time in as many days, the self-diagnostics of the car alerted me to something. I interpreted this symbol, as overheat warning…yet the actual temp gauge was normal. We were cooking at about 70 mph, so I slowed down and the warning went off. Sped up, warning on, slow down, off. The temp gauge was steady the entire time. As the gauge and the check circuit are driven by two different sensors, I figured one was either marginal or just straight up lying to me. We made it home without incident, modulo the need to pickup the kids from school on the way without room for them, due to the bedroom door, but that side adventure doesn’t really come into it.

November 1st: Lisa comes home from her class and says, “When I shut the Jeep off, there was a weird gurgling sound. Also when I was getting gas it seemed like there was a of steam coming off the hood, but it was also raining, so wasn’t sure.” I was getting over a cold, so was in no shape to do much about at the moment.

November 2nd: Feeling myself again, before running the kids to school, I popped the hood on the Jeep. A cracked radiator — well, this car ain’t going NO WHERE.

So, I hopped in the Audi, and miraculously it started without the booster box, however the temp warning alert in the check module went off immediately. Okay, everything is stone cold, something doesn’t make sense. On a hunch, I though that maybe the symbol was actually a poor representation for a low coolant level warning, so dropped some water in the reservoir, light went off. Fine, onward, were almost late for school.

It turns out the local NAPA had a radiator and hose kit in stock for the Jeep. Lisa took the Rx-7 to pick it up, then continued on some other errands including taking one of the kids to an appointment on the East Side. Half way there the phone rings, “I’m on the 520 bridge and all the warning lights just came on in the car.”

It was at this point, we figured we’re under a curse this week or something. I said as long as the gauges look good, continue on the to appointment. No reason to stop the car unless the temp gauge spikes.

After she sent me a picture of the dash, I noted that the volt meter was REALLY low. I advised to do as I had done a few days earlier with the other car, “Okay, drive home with no headlight, defrosters, etc — I think you’re running on battery power only. It’ll probably be okay.” I wasn’t as worried as there are no real electronics in the Rx-7 to power, just the ignition coil.

Good News: It was, she made it home, volt meter showing about 10 volts. The two of did the radiator swap on the Jeep later in the afternoon in record time, 90 minutes start to finish!

It was a completely uneventful procedure and was done Just in time for her to go grab the kids form school.

After she left, I popped the hood on the Rx-7.

Yep, that’s the alternator belt, no longer very belt-like, laying across the top of the engine. At least diagnosis was easy.

In 25 years and probably close to million miles worth of driving I’ve never lost or broke a belt — and here we lost two within 5 days.

November 5th: I brought the brand new battery for the Audi back to the store to for a warranty replacement. It’s only 6 months old and it just won’t hold a charge right. The car produces a solid 13 volts regardless of how many electrical accessories you turn on, hence it’s not the car. I knew I was in trouble at the store as soon as they brought out their battery tester. It is, of course, one of those new fangled electronic units, which perform a “Simulated Load Test”. We had a lot of issues with these when I worked at the BMW shop. It turns out that you can have a Lead Acid battery that holds a surface charge for a little while, but then will experience a voltage drop and doesn’t have the Amperage it needs to actually start the car, but that surface charge will fool the simulate load tester.

Of course, the test procedure for these is, Step 1: Charge battery. Step 2: perform the simulated load test. In the old days, we had a test machine that would induce a true load on the battery, and you could see how it would recovery from a load — or not. Anyway, not surprisingly, after the parts store insisted on charging the battery for two hours before testing….it passed!

I lamented to the guy how we used to get this all the time in the BMW shop and relayed the following experience. That we used to see the same symptoms, battery randomly doesn’t have enough juice to start the car. We’d charge it, we’d do a draw test to be sure there were no parasitic drains, and the new (at the time) tester would always pass the battery. And the customers would always come back, pissed off because their car didn’t start the next morning. He swapped the battery, thanks man!

The part I didn’t tell him, is that in the shop, I figured out how to “cheat the test” in order to get BMW to pay for a new battery. I’d turn on a bunch of accessories, then run the “Simulated Load Test”. By pulling a little bit of that sweet sweet surface charge off the battery, it was enough to get it to fail. I believe it’s been long enough, that information is no longer actionable in a court of law.

Anyway, we’ll see what the coming week brings with regards to the Audi’s battery.

One Week Recap:
2 – Alternator Belts
2 – Low coolant situations
1 – Blown radiator
? – Random no starts
1 – New Battery

That’s quite enough for me for a while.

Update: A week later, and the intermittent no-start in the Audi seems solved. The starter spins the engine with gusto every morning!

First, on this car, it is not just a “power steering” pump. That would be far too pedestrian for this Tutonic Wuderauto. The same pump also supplies hydraulic pressure to the power brake booster. On some Euro-market cars, they took it a step further, and it also ran the self-leveling rear suspension. Regardless, it’s a critical component, running a several important systems, with a lot a plumbing.

To get started, I figured I’d top up the fluid reservoir and see if any fluid fell out anywhere. This car, of course, doesn’t take any run of the mill power-steering fluid which you can find on the shelf of any auto parts store for a couple bucks per bottle. No sir, not this car. Pentosin CHF 7.1 is the specified fluid.

CHF 7.1 is an older mineral oil based formulation, and unsurprisingly has gotten hard to find. There’s a lot of mixed information out there on:
1) If it’s safe to mix it with the newer CHF 11s synthetic stuff
2) If a system originally spec’ed for 7.1 can even take 11s without exploding
3) When Audi actually made the switch over from one to the other.
Taking a best guess after reading too much, I decided to just go with the older mineral oil based fluid. Then I went to buy some.

Back 15 years ago when I needed to buy some of this stuff, it was kinda pricey, but holy smokes, current prices are over $50 / quart! The system needs about a quart to completely fill. Fine, except I have a massive leak. To avoid pouring $50 directly on the ground, I shopped around. I found that Beck/Arnley makes a compatible fluid for like $12 /quart — perfect.

Having secured three quarts, I dropped some number of ounces in the system and observed. I suspected the leak was somewhere down where the lines met the steering rack, as things looked pretty wet in that area. I put a shop towel down there to see if it caught any drips. I didn’t see anything at first, so left and came back to it later. What I found later, was that all the fluid was gone from the reservoir and my towel was soaked — okay getting closer!

Can you see where the lines are? Yeah neither can I, but they’re somewhere back above the vicinity of the blue shop towel.

I repeated this exercise a couple of times; armed with lights and a mirror I was able to determine that indeed, the pressure line to the rack had a pretty decent drip. Access to lines on the rack are TIGHT, but moving the reservoir out of the way and with enough finagling I was able to get a socket on it and removed the banjo bolt.

A split washer. There’s no way that’ll hold anything, clearly.

This system calls for a solid zinc crush washer. Eagle eyed, readers might note, that the above washer is neither solid, not zinc. So, some shoddy previous work had reared it’s ugly head here. No problem, I’ll just grab one from the parts store.

Back in the day, if I needed a crush washer in some size, I didn’t really need to know or care about the particular size. I would take the old washer to the autoparts store, and pick one out of a box that matched for about $0.25. In the modern autoparts world, which has been completely destroyed by MBAs and consolidation, there’s nothing in the store that doesn’t have a separate sku to be scanned, tracked and dropped from inventory because it’s in the bottom 20% of things sold in a given year. In other words, there are no longer boxes full of assorted washers for $0.25 each.

Given this horrifying retail situation, I ended up digging through Audi Parts diagrams, to find a VAG part number, then attempt to cross-reference it in various systems. In the end, I found the washers I need and it only cost me like $5 and 3 hours of research. With the hose reinstalled with fresh washers it was time to put more Magical German Mineral Oil (Deutscher zauber öl) in the system.

I filled the reservoir and let it sit overnight. The next day, there were no drips! I figured I’d attempt to bleed the system. I did so by spinning the pump pulley by hand. It felt a little lose, but the fluid level dropped indicating we were circulating fluid into the entire system. Wait a minute, this pump pulley is REALLY lose — it shouldn’t wiggle up and down…Oh, look fluid is now pouring out from behind the pulley. Sigh.

In the best case this meant that the main pump seal was shot — I guess the previous owners didn’t remove the belt “to protect the pump” in time and in fact burned up the seal. I hoped the damage was limited to the pump seal.

A little dismayed, but still undeterred, I found a pump rebuild kit, which contained about about 2 dozen o-rings and the pump shaft seal. Once the kit came in the mail (we’re like 2-3 weeks into dealing with this pump at this point) I removed the pump, disassembled it and….oops. Junk.

This thing was just destroyed. So, now I had to make an attempt at sourcing a new pump. NO parts house had a rebuilt unit. Worse, there are three different versions of the pump and each version of the pump required a different set of banjo bolts to attach the hydraulic lines. The bolts, of course, are no long available at any price from anywhere. I reached out to the local Audi groups and someone had a “recently” rebuild unit which matched mine on the shelf — $200. Fine.

Of course, I needed a new set of crush washers for the pump end of the hoses. Two pressure lines, one return line for a total of 6 washers. I went back to the parts diagrams to get part numbers. I was able to cross reference those numbers and found sizes — but no listings for most of them. Then remembering back again to the box of washers we used to have at the AutoParts store, I went to Amazon and found my own box of 300 crush washers in assorted sizes for $15. Done and Done. I now have a lifetime supply of copper crush washers.

In the meantime, I pulled the strainer from the reservoir and found it full of metal shavings from the old pump and did my best to get it all cleaned out. I’m sure there’s an unfortunate amount of metal in the brake booster and the steering rack still, but I don’t have a good way to flush it all out, so it all went back together. I filled the system with fluid, ran the pump by hand for some initial circulation, saw no drips, put the belt on and then, the moment of truth.

I started the car. The fluid level dropped. I topped it up. The pump turned and was quiet. I had to pump the brake pedal a bunch to bleed out the hydraulic brake booster and of course spun the steering wheel back and forth a number of times. I topped up the reservoir again. The pump kept turning and remained quiet!

There is the smallest of a small fluid weep at the main pressure fitting on the pump, the copper washers are just a little harder than the OEM zinc washers. The Banjo bolt calls for 40ft-lbs of torque, I put 45 on it. As the bolts are NLA, I just need to source some softer washers. But we had brakes and steering now! One step closer to being on the road!

Starting on the passenger side, the old hose came loose from the hardline without too much trouble and unscrewed from the caliper without drama or hesitation. The new hose went in and I felt good. Total time, ten minutes. The first thing that just went according to plan on this car so far!

Then I moved to the drivers side. I won’t give a time estimate on how long the driver’s side took. Note: It’s never a good sign when you have to break out the vice-grips when working on brake lines.

And then it gets worse.

Sigh — it was too good to last. At least we were experts in bending new hard lines at this point. So a trip back to the store, some cutting, flaring and bending, and there is now a new hard line running from the ABS pump to the new hose for the front left wheel. I should note, that this was like a 12 inch line, the pump is just on the other side of the wheel wheel in the engine bay. I thank my lucky stars, that this didn’t happy on the passenger side — I think 1/2 the engine bay would have had to come apart to route the new line.

It was also during this hardline replacement that I became intimately familiar with the difference between a double and a bubble flare on the ends of your tubing. I won’t go into detail here, but you can find some nice pictures and an explanation here: https://www.rtsauto.com/brake-lines-for-bmws-and-e30s-the-bubble-flare-not-the-double-flare/ The Important part of this story, is that if you attempt to put a double flared bit of of tubing (as I had just created), into a fitting that wants for a bubble flare (as does the ABS pump), it’ll never seal and will just squirt fluid everywhere, no matter how hard you tighten the nut. Thankfully, I didn’t just keep cranking on it and figured there must be something wrong, at which point I inspected the end of the old line and had my moment of….Oh, these ends look different. Lesson learned.

With that out of the way, I bled the system out, got a nice firm pedal and felt accomplished for the day.

Note: The following is little out of order from how it happened, but is presented here to keep the brake saga all in one place. The Power Steering Pump Saga took place between the above and the following.

One thing that was extra fun, in moving the car around the driveway before the brake system held pressure, is that that parking brake was also non functional! This was due to bad parking brake cables. The weather proofing in the cables in the car had become compromised some years before. The left side was marginal, the right size was pretty well seized up. By some miracle, I was actually able to find brake new parking brake cables from a specialty parts house.

Now, the hardest part of this job, ended up being the fact that the parking brake adjuster is seized up and I couldn’t break it free. I didn’t want to crank on it too hard for fear of snapping it and being in worse shape. Unfortunately, I didn’t think to grab a picture of what’s involved here, but this image from the parts book helps illustrate:

That big wing nut looking thing, is attached to the rod on the backside of the handbrake. The cables simply slip over the hooks. Removal should be a trivial matter of unbolting the bracket (oops, can’t seized, remember?), and sliding the old cable off…which as it turns out, couldn’t really happen either as the bracket itself had swollen with corrosion over the years. However, with enough cursing, grunting and struggling, I eventually persevered and got the old cables off the ears. Removal of the cables from the calipers went smoothly enough. Great, lets put the new cables on.

And here dear reader, is where I almost lost my mind. It turns out that the windows in the ends of the cables, which slide over the ears of the bracket were ever so slightly smaller on the new cables. Maybe if everything were in spec, this would have been fine, but if you recall from above, I had a devil of a time getting the old cables off, due to everything being chunky. So, I got out the file and started cleaning up the ear bracket. Did I mention, it’s still in the car, between the driveshaft and the underside of the tunnel?

For the next hour or so, my life consistent of: file file file, hand cramp, try to fit cable. Rinse and repeat. I eventually got the driver’s side cable to slide on. Looking at the cable for the passenger side, I gave up. The window was even SMALLER and that side of the bracket was even more swollen with corrosion. So I did what I should have done in the first place. I broke out the dremel, and opened up the window in the cable. It took me 45 seconds. Sigh.

I figured the work on the brake system should be fairly straight forward. A few hard lines to replace, rubber hoses at each corner and voila, we should have a stopping car. Sadly, this adventure in braking ended up not being nearly so smooth.

I started in the right rear, a good place to start as it’s the furthest from the master cylinder and also the corner that was completely missing a brake line. Disassembly was relatively straight forward, I decided to replace everything rear of the junction block forward of the rear left wheel as it was all rather crusty. I ran to the local auto parts store and attempted to purchase some new hard lines as well as the rubber brake hoses for the car. It was at this point a couple facts about this car really hit home.
1) They didn’t make a ton of these — Which means there’s not a lot of part houses making parts for them.
2) It’s a 35 year old car, which compounds the first problem. This actually used to matter less. Back in the 90’s when I worked in a parts store, we literally could get damn near anything for any car next day, maybe 2. There was a large network of independent distributors which carried parts from a endless list of aftermarket parts companies.

It turns out that the aftermarket parts industry has changed DRAMATICALLY in the last 20 years. We’ve gone from a vast network of independent/semi-independent parts suppliers to big consolidated monoliths such as the O’Reilys and AutoZones of the world. These guys own the retail outlets and the intermediate warehouses and if it’s not in the catalog, you can’t get it.

Thankfully, places like RockAuto.com and a multitude of specialty parts houses still exist out there; however; that meant I was waiting a week plus for my “I don’t even have a listing on those!” brake hoses.

In the interim, we got some hard lines and double flare tool, and Lisa crafted some beautiful new lines to match the old ones..or a best guess of what was left of them.

You might think that’s all there is to this tale — but you’d be wrong. Before I got too far into it, I decided to see if I could crack the bleeders loose on the rear calipers for when the system went back together. Of course, they wouldn’t budge. After hours of soaking, heating and hammering at them, the inevitable happened, and I snapped the end of the bleeder off in the caliper.

I dutifully went back to my local parts houses and inquired. Much like with the hoses, some didn’t have a listing, others told me $150 each, we can get them in two weeks, with $15 shipping. This simply wouldn’t do.

So I did what any person who’s frustrated at delays and wants to save a couple hundred bucks does — I bought a new set of bleeders for $5 and made a plan involving drill bit and thread taps.

As it turns out, carefully drilling out the old bleeders, stepping up the bit size until just the barest bit of metal remained in the old threads and subsequently chasing the threads with a tap, was quicker and easier than the hours I’d spent soaking, heating and hammering the old bleeders trying to get them out. Something to keep in mind for the future.

Drilled:

Tapping:

New bleeders installed:

Eventually the rear hoses came in and I laid everything out, ready to go back in, old stuff above, new below. From left to right in the image below we have, left rear caliper, brake hose, line to the junction block, then the other line from the junction block into questionably named Retardation Sensitive Brake Pressure Regulator (The rusty cylinder there, more on this in a moment), the missing line, right hose, right rear caliper. Please note Lisa’s beautiful craftsman ship on the new lines on the bottom…they’re were straight as arrow when she started!

The purpose of this Brake Pressure Regulator is well covered in this instructional video:

If you can’t be bothered to watch the totally 80s-tastic video, basically, there’s check valve in there, under hard cornering, a little ball blocks the flow of brake fluid, there by reducing pressure the caliper and preventing inner wheel lockup during hard cornering and braking as you might encounter in an emergency move.

This device is especially critical in a car such as this with it’s completely ridiculous 62/38 Front/rear weight distribution. This is of course to do the giant cast iron inline 5 cylinder engine hanging out completely forward of the front axle (here’s an opportunity to give your children an object lesson in leverage) — a mechanical design language for Audi that continues into the modern era.

But I digress. Everything went back together easily enough and there was only a minor mishap when bleeding the system out — The LR hose wasn’t quite tight enough — I put the pressure bleeder on the reservoir…and wondered why I wasn’t getting much out the bleeder on the right rear…until I looked across and saw the steady stream of brake fluid pouring from the other side of the car…oh well.

Unfortunately, it was at this time I also noted that one of the e-brake cables was seized up. But that’s for next time along with swapping out the front brake hoses.

Yep, that rubber tube, at one time in the possibly distant past, used to contain a metal line. The metal line would have been connected to a to a rubber hose, which then connected to the brake caliper. Via this system of tubes and hoses, hydraulic pressure is supplied to the brake calipers when you press the brake pedal — at least in an idea world. In our world, not only was the rubber line to the caliper missing, but the metal, tube had rusted into oblivion. Now, I’m not sure the purpose of the rubber sheathing here. None of the other brake lines have it and the only thing it served to do was to trap moisture and rot out the line. Oh well, that should be an Easy Fix ™.

I poked around some more underneath, and identified the where the crack in the exhaust is, which should be another Easy Fix ™ for a exhaust shop. I then proceeded to make an attempt to untangle myself from the trailer…

Once extracted, I moved under the hood. While dirty, nothing seemed out of the ordinary, aside from the empty Hydraulic System reservoir, which was a known, disclosed issue. I wasn’t able to identify the leak right off the bat, but the frame rail directly underneath where the pressure hose attached to the power steering rack looked pretty darn wet; a decent place to start.

The above shot is me pontificating a bit on the CIS fuel injection system, I’ll spare you the video in which I made a number of factual errors, as I’m new to the system, but let me say this: This is a system which, many people dislike for a variety of reasons — it’s somewhat complex, hard to diagnose, and hyper-sensitve to any faults in the system, to name a few. Indeed, a ridiculously large percentage of the Factory Service manual, is dedicated to the troubleshooting and repair of the system. I also have basically no experience with it, but I will observe that the sheer number of Volvos, Audis, Mercedes, etc with 200k+ miles on the clock which run a CIS system means it can’t be *that* bad. Right? RIGHT?!?

Anyway, with some post-pontificating poking, I found the rubber brake lines in the front were cracked something fierce. Not surprising, and I was planning on replacing them anyway. Remember, you can go as fast you want, but it doesn’t matter unless you can stop.

Also found that fuse #4 was blown, replacing it made one interior light in in the driver’s foot well light up when the door was opened. I guess that’s something, but it was clear there were a number of electrical issues as well. Lack of interior lights, the blown fuse, non-functional gauges….Did I mention the back seat wouldn’t latch into place because the wrong size battery was back there? Wait, did fuse #4 just blow again?

It was a this point we pulled it off the trailer and pulled it into the backyard to get cracking on the brakes and the power steering system and electrical gremlins.

“Warning, you will reach your destination after they close.”

How is this possible? They close at 4, Vancouver is less than 3 hours away and it’s just barely past lunchtime! Due to an accident on I-5 between Tacoma and Olympia, it was going to take an extra hour plus. No good. Once we cleared the traffic jam and had a clear shot to Vancouver (ETA 4:10 pm), we called the office and explained to them the situation — We hit traffic, we have an appt to pickup a car tonight, no trailers anywhere, etc, etc. They said they had to leave at 4:00. I put the pedal to the metal.

Now, Lisa says I was driving a little “scary” at this time, exceeding the speed limit in the rain, in her Dad’s truck trying to make up time. Sir, if you’re reading this, I have no comment on Lisa’s claim, I would just note that you received your truck back with no damage and that’s all really matters.

In order to distract herself from the near death experience greeting her continuously through the windshield, Lisa called U-Haul customer service to see if there were any other car trailers in the area at facilities which were open a little bit later. The agent said, “There’s a note on your reservation, that they’ll be able to wait until 4:10 for you.” The ETA had dropped to 4:07 by this time. 3 minutes to spare, no big deal! This did cause me to let a bit and bring it to a low simmer.

As it turns out, we pulled into the place at 4:04 and thanked the people profusely as they checked us out. Friends, if you’re ever in need of U-Haul equipment, rent from the folks at I-205 Mini Storage in Vancouver WA. Good people. With trailer in hand, or rather on hitch, we proceeded the additional 1:20 to our destination.

The remainder of the trip down was uneventful, I dare say it was pleasant even, as we were under no time pressure, the weather had cleared and the countryside was quite pretty.

Eventually we wound our way through the hills and farmland and happened upon our destination. If you look VERY closely, you can see the unmistakable roof-line of our quarry in this picture somewhere.

One we figure out the logistics of getting the extra long truck with trailer into the barnyard where the car was, we started looking the car over. I knew it needed some things, but I wanted to be sure I knew what I was getting into. We poked at the car over the course of an hour. I will admit the car was little rougher than I expected cosmetically, but it was fairly represented.

I made an offer, we haggled a little, sold for $1800.

Once we pulled away, I think we’d been at this guys house for over two hours. In addition to buying this car, we talked about all kinds of car stuff and he showed us some other treasures he had on the property. The seller being such a nice guy was really the cherry on top of an already fun adventure.

We stopped for dinner in Forest Grove and took the first picture of it being ours. We pulled into our neighborhood about 1:00 am — in all, about a 13 hour adventure.

Next up…Diagnosing and repairing things!