Audi S2 progress update 2018-11

It’s been a while since my last update so I thought I’d write a short post about what I’ve been doing lately. Little was done during the summer as I was doing summery things in addition to it being way to hot to be working in the garage…

A couple of weeks ago, I got the urge to start the project as it was just sitting in the garage collecting dust.

The car was stripped of all interior parts so this was my first mission. I also decided to upgrade the heater core to one of newer date with the upgraded controls.

Climate system upgrade

The car, being a 91-model had the first generation electrically operated climate system. I got a salvaged second generation climate system when I bought the car so I decided to install it. This project required me to rewire the entire system as even though the connector was the same, hardly any one wire was wired to the same feature on the car. I spent hours and hours trawling  through schematics to identify which wire should be connected where. I ended up connecting almost all pins on the new system, but there were some pins which I did not connect. I think some of these were the rev-counter and full throttle wire which should be connected to the ECU. It was a little scary to connect the battery after rewiring and fitting the new heater core, but everything seemed to be working fine. The only thing that needs to be fixed is the display on the heater-controls as some of the segments does not work. This is not important for the main functionality of the climate system so I’ll try to fix it at a later time.

Refitting the interior

Roof lining

I did get all the parts for the interior spread amongst several boxes and containers so the next job was to install it. The first thing I did was to rip off the old roof liner as it was dirty and had almost fallen off by itself. The original color was light gray-yellow-ish, so naturally, I decided to go for black. The first attempt failed miserably as the fabric managed to glue itself to itself… With that lesson learned, I recruited help from my wife and tried again, with a much better result! I did get some wrinkles, but I decided not to do it a third time. Finally I used a couple of jack-straps to glue the roof liner assembly to the roof of the car.

Dashboard and plastic trim

After installing the upgraded climate system I put the dashboard back in, the roof carpet, the plastic trim, the seats and the rest of the bits and pieces needed. No real difficulties here except fitting the small compartment below the steering wheel… Too many wires… I got it in there, but it is not fitted exactly as it was from the factory.

Boost gauge

As this is a turbo car, it needs a boost gauge. I don’t understand why Audi didn’t fit a boost gauge from the factory, especially on the S-models… I’ve seen many others fit the boost gauge in the middle of the three air vents in the center of the dashboard so I decided to do the same. I have many air vent fronts from the previous owner, so I wasn’t afraid to destroy one to build the boost gauge frame. I wires the lightning for the boost gauge to the light controls such that it has light when the main light switch is on (same as the rest of the gauges in the dash). To get the manifold air pressure to the gauge I fitted a y-piece on the hose to the ECU.

Front fender

I test-fitted the front fender just to see what I had to work with. The fender is not an S2 original, but some sort of aftermarket RS2-copy of some kind. One of the fog lights were broken so I had to find a new one in order to pass the requirements for registering the car. The fog lights were the same as an old Porsche 933 and I was lucky to find a pair on eBay which is noe en-route in the mail.

Suspension and sub-frame upgrades

I decided to upgrade the suspension as I saw some rotten bushes and rusty parts on the rear subframe. I disassembled the entire rear subframe of the car and started ordering parts. Currently, this is what will be replaced/fixed/upgraded

  • KW v1 coilovers
  • Poly-bushes all over
  • Whiteline rear anti-rollbar
  • New wheel bearings on all four wheels
  • New steel braided brake lines
  • 034 motorsport density line differential mounts
  • 034 upgraded rear control arms
  • New strut tower front bearings
  • New steering control arms
  • New guide joints all over

I’ve added an album with pictures from the suspension and subframe work so far.

Clutch, suspension and downpipe upgrade

Been a while since my last update, and the reason is that I’ve mainly been waiting for parts…

About a month or so back, I was out driving and noticed that when pulling in 4th and 5th gear, the engine revs increased, but the speed did not. I was hoping that I could get away with the engine upgrades without changing the clutch, but it seems it wasn’t so. I decided to upgrade the clutch instead of just getting a new standard piece. After some research, I opted for the 240mm FX100 clutch designed by ClutchMasters as well as a new 240mm lightweight single mass flywheel to match. Upgrading to a larger sized flywheel holds a lot more torque than the original 224mm dual-mass one in addition to the added gripping power og the new clutch. Installation went flawlessly without major hassles, but I’ll tell you, lifting the gearbox in place when alone is not a straight forward job… I laid on my side under the car while guiding the gearbox with my hands and operating the jack with my feets 🙂

While the car was already on the jack stands and the driveline was disconnected, I decided to get new front suspension control arms and upgrade to polyurethane bushing as the original bushings were worn out. I got a complete set of front control arms and a complete set of bushings for street use (although I got an upgraded (track) piece for the lower-front control arm on both sides). The tricky part installing these were to get the original rubber bushings out of the control arms. I don’t have a hydraulic press which ment getting the hammer and angle grinder out. After some struggling, the original bushings came out without damaging the control arms and the polyurethane bushings were installed using the supplied grease. I also had to replace the rear passenger side control arm as it had some damage and was somewhat bent… I also painted the inside of the wheel wells with an anti-rust/corrosion solution and washed all the parts that had to come off.

I also upgraded the exhaust downpipe as I only had done the first 30cm or so when upgrading the turbo. I decided to go for a 3in pipe all the way back to the 2.5in Simens sports exhaust. In addition to this, I fitted a flex-joint so the exhaust can move without damaging the turbo as well as a v-band joint for easy removal in the future. I also fitted a third lambda-connector in case I want to install a wide-band air-fuel gauge in the future.

Brake upgrade

As the Audi A4 B6 standard car is not known for its awesome brakes, I figured it was time for a brake upgrade.

I spent some considerable time researching brake upgrades for the car and after a while landed on a set up that wouldn’t cost a years pay (read big brake upgrade) while still providing a big improvement in braking performance. I managed to track down a set of callipers and brackets from an 2006 A4 B7 2.0T avant witch had the 320mm front disks. These are bolt on replacement callipers for the A4 B6 which fits the project perfectly. In addition to the callipers, I bought a set of yellow-stuff brake pads and slotted 321mm ventilated disks produced by EBC. Since then, I’ve heard that people have had bad experiences with the yellow-stuff brake pads but I decided to give them a try and see how they behave. I also bought a new set of Bosch rubber brake lines to compliment the new callipers.

As of tonight, I replaced the right side brakes before i got hungry and decided to get some food. The brakes fitted perfectly and bolted on without issues.

I’ll update after I’ve done a test-run with both sided replaced.

Update: Finished replacing and bleeding the front brakes and took it for a test run. Unfortunately, it was snowing, so I couldn’t do any hard brake tests, but I drove it for a good half an hour to get the protective film off the disks and pads. It seems to work pretty well and I defiantly noticed an improvement over the standard disks and pads. I took it out for a ride a few days later and noticed that the brakes has reduced performance when cold – this was expected though, and shouldn’t be a problem.

All in all, very happy with the upgrade. Time to make a plan for replacing the rear as well. I’ll write down the part numbers in case someone would like to do the same upgrade.

Calipers: 4F0615123 (left) and 4F0615124 (right)
Disks: EBC USR1423
Pads: EBC DP41495R (EBC yellowstuff)

Link to the shop –

Project update 2018-01

After fixing the misfire issues, I decided to protect the coils a bit by creating a rudimentary heat-shield over the turbo and exhaust manifold. I modified the original heat-shield to fit alongside the PCV modifications which turned out ok. I’ll post some pics of the engine bay as I’ve completed the upgrades I intended to do this time around 🙂

Misfires fixed!

After many hours of head-banging I finally solved the misfire issues! I had previously compiled a list of possible issue that I used as a checklist for eliminating possible faults one by one. 

Now, lets review the list of suspects from an earlier post:

  • Bad coilpacks
  • Bad gas (water etc.)
  • Bad spark plugs
  • Bad MAF
  • Vacuum leak
  • Low fuel pressure
  • Bad crank position sensor
  • Bad O2 sensor
  • And several others.

From just about every post and article I read on the internet, coils and plugs were on, or near, the top of the list of usual suspects. I had previously upgraded coils and plugs when I tuned the engine to stage one back in november 2016, so I figured they were OK. I did fix a few vacuum leaks thinking it was it, but the problem was still there.

I then went on and replaced the following items:

  • Spark plugs
  • MAF
  • Crank position sensor
  • O2 sensor
  • Fuel filter
  • MAP sensor
  • PCV valve
  • PCV check valve (pancake valve)
  • Misc. check valves

As it is a 15-year old engine, most of these parts needed replacement anyway, so I figured this was a golden opportunity to get it done. Unfortunately it did not resolve the misfire issues and I was running out of ideas.

As a stroke of luck, I got a hold of four coils from my brothers 2001 VW Passat before he sent it to the scrappers. I threw them in there to see if it made any difference – and voilà – the engine purred like a kitten!

Lots of work, lots of parts changed and the issue was what everyone said it would be… Lesson learned, listen to the majority and change the obvious culprit first.

Turbo Inlet Pipe v2.0

As I am afraid of water entering the inlet system, I decided to rebuild the turbo inlet pipe. I had initially though of going this route, but as space is tight, I mean really tight, I didn’t do this the first time around.

Since the 90degree pipes I already had didn’t have a sharp enough bend, I had to improvise and create a sharper bend by cutting the 3in pipe in a 45degree angle and weld the two parts together. I suspect this might not be the best solution as air have to pass through the sharp bend just before the turbo, but it’ll have to do for now. I also had to reroute the crankcase ventilation system in order to fit the PVC pressure release valve (which I’m replacing because I suspect it being bad).I reused some of the original piping and rubber bends to route the system close to its original path. This turned out pretty good and actually looks quite nice! 

I’m currently waiting for a 3in to 2.75in silicone reduction hose to fit the original mass airflow meter to the 3in intake pipe so I cannot test it quite yet, but it will be nice to hear how it sounds. The previous turbo inlet pipe (first version behind the fog-light) was a bit longer than the original one which resulted in the dump valve being almost inaudible from inside the car.

Since the air inlet is now very close to the exhaust, heat might become an issue. I decided to modify my old heat shield (created from an old computer case) and placed it in between the turbo and the air filter.  

I’m attaching some pictures from the build, but remember – I’m not the best welder… Still learning though 🙂

Vacuum and misfire issues

Time for an update. I got the engine running a little a few weeks back and at first it looked like it was going well. The engine started up as it should and idled normally. I ran the engine at idle for a little while just to warm it up and listen for unusual noises. All temperatures were in the green so I decided to go for a test run. I ran the car lightly at first just to make sure things were running smoothly before I did a slight pull when running up a hill. The turbo started charging and everything looked good, but then, misfires. A lot of misfires. I pulled over to a parking lot to do a quick visual inspection (the engine was still running) but couldn’t see anything. As quickly as the misfires came, they disappeared. I did another light pull and this time it behaved normally. I decided it was a one-time thing and went for a longer trip while still driving pretty lightly. It ran fine for about 10 to 15minutes before I went for a pull in second gear. Like before, it started to misfire, this time more severe. I pulled over to see if any of the pressure hoses had come loose, but they were all fine. I had my VCDS running and it was showing random misfires on all cylinders as well as the lambda O2 header element being bad. After a restart of the engine, the misfires were gone. I drove home to do a more thorough inspection of the engine compartment and found the crankcase breather pipe (the plastic 90degree one) was completely broken.

I did some research and found quite a lot of reasons for why the engine might misfire randomly on all cylinders:

  • Bad gas (water etc.)
  • Bad coils
  • Bad spark plugs
  • Bad MAF
  • Vacuum leak
  • Low fuel pressure
  • Bad crank position sensor
  • Bad O2 sensor
  • And several others.

I quickly ruled out coils and plugs since I find it strange that they should all fail at the same time. They are also less than a year old. The misfires should also be there (to some degree) all of the time, not intermittently like the ones I had.

A vacuum leak is pretty common for these engines, and since the crankcase breather pipe was broken, I decided to get a new one. I also ordered a new O2 sensor, the PCV valve, a few hoses and a crank position sensor. When removing the intake manifold, I saw a few vacuum hoses being worn down so I decided to replace them as well.

After replacing the O2 sensor, the crankcase breather pipe, the PCV valve, the crank position sensor, a few vacuum hoses as well as the intake manifold gasket and the throttle body gasket I has high hopes that the issue was resolved. To my disappointment, it was not. When going out for a test-run it ran fine at first, but the misfires all came back when I did a light pull. I managed to get back home and did a quick check as well as changing the spark plugs. No immediate change with new spark plugs, which was expected, but as it is a relatively cheap fix I decided to just get new ones. Using VCDS I saw that the short term fuel trim was fluctuating between -2 and 2% and the long term fuel trim was stable at about 3.2%. I read that the long term fuel trim should normally be a little lower so I cleared DTCs and saw the short term values being very high at more that 25%. After a few minutes, the long term increased to about 3.2% and the short term stabilised between -2 and 2% like before. I deduced that it had to be a vacuum leak somewhere, but was not able to find any so I went in to grab some food and do some research.

As I couldn’t find a obvious vacuum leak, I decided to replace the PCV relief valve (pancake valve on the TIP) as it’s now about 16 years old and is likely to be passed its prime.. When removing the intake piping where I found some water having gathered there. That is most certainly not good since it could be sucked up by the turbo when doing a pull, getting mixed with the fuel and wrecking havoc with the fuel mixture… I decided that I have to rebuild the intake to move the air filter up into the engine compartment. The problem with this is that it’s a very tight squeeze getting a 3in hose passed the headlight…  

That’s it for now – I’ll update once I have some news 🙂

Air filter splash shield

As I said in my previous post, I’m worried that water may enter the air filter and cause some issues when driving in wet weather. This is because I have moved the air filter down behind the front bumper fog light. I had a small bit of metal plate laying around from my previous heat shield which I modded to fit around the bottom and front part of the air filter. It’s not the prettiest thing, and it will not prevent large splashes from entering the air filter, but it might help keeping the worst of it away. To prevent the air filter from moving to much, I made a couple of rudimentary brackets as well.

I also discovered a couple of bumps in the intercooler piping close to the turbo, which I suspect may be from parts being slung out when the previous turbo died. Need to check if there are some broke turbo parts in the intercooler before I fit it all together again.

Custom downpipe and turbo inlet pipe

As I’m fitting a non-standard turbo, I had to manufacture a new downpipe for the exhaust and a new turbo inlet pipe in addition to several other hoses and fittings. As I have never done this before, it was a good learning process and the result did turn out well enough.


The main goal here is to create a short pipe section that runs from the turbo to the original post-cat exhaust stub as the original cat does not fit the new turbo. The turbo (GT2860RS) came with a short 5-hole to 3in v-band fitting. For the other end, I cut of the other flange from the original cat. I bought several 3in pipes and bends in addition to a 3in to 2.5in reduction pipe as the original flange did not fit the 3in pipe directly. I welded the pipe together using a MIG with flux-core thread, which turned out ok, but the flux-core creates a lot of spatter and take a lot of work to get “pretty”. I might invest in some gas for my next project…

Turbo Inlet Pipe (TIP)

As the original TIP didn’t fit the new turbos 3in inlet port, I had to make a new one. In addition to this, the new turbo sits closer to the front of the car than the original one making it hard to route a 3in pipe passed the headlight to the original position of the air filter. I had to route the pipe downwards under the front-bumper brace and outwards to the right side just behind the fog-light. I’m worried that this might cause issues in heavy rain if the air filter sucks in water, so I might create some kind of a shield protecting the air filter from water splashes.  

Oil pan and failed turbo particles

When I changed the oil-return pipe, I noticed something that looked like ball-bearing parts sitting in the oil-return hole in the oil pan. I decided to take of the oil pan to clean it and at the same time clean the oil-pickup pipe for the oil pump. Good thing I did as I found more shattered turbo-parts in the oil pan when I got it off the engine. I also found one of the engine mounts being broken, so I decided to replace both. I am also replacing the front engine snub mount and the sway bar end links.