Baeloro

To start this thread off, I purchased this car in Feb last year with 180k miles. I have the canadian model, which is specced in metric for the guages and odometer, right now I'm sitting a 309k km, or 192k miles. Here's a list of the work I've done in the last year in response to the codes I've gotten and problems it's had:

Initial Purchase:
Catalytic Converters (both)
Radiator Reservoir tank
Rack and Pinion

Feb this year:
EGR Sensor (have not cleaned EGR valve yet)
Oil Pan Gasket
Thermostat control sensor (the one close to the throttle body).
Plugs + wires
Thermostat

This Week:
Throttle position sensor + throttle body gasket
Vacuum lines
Cam Vent lines

When I first bought this car, I noticed a sulfur odor sometimes when accelerating or right after parking. I had the dealership run diagnostics on the Cats and they ended up replacing them for me, I had them do the R&P too because it had a leak. Some time later, I took the car down to have emissions done, and I was throwing codes for EGR sensor and the thermostat sensor, with a check engine light and several monitors reporting not ready. After replacing the EGR sensor and thermostat sensor, I paid to have the monitors reset and it somehow lasted long enough to pass emissions (even though I had the waiver signed).

Then on the way home check engine light came on again and we found out that it was just reporting Thermostat sensor again with some misfires. I noticed it was taking far too long to warm up the car, so we pulled the front and end and sure enough the thermostat was not operational, it was stuck open. We got that replaced got everything back together, then noticed it was running rough at idle. So I drove it for a bit, started getting throttle issues, and an error code came back as TPS sensor. We got that replaced, redid all the vacuum lines and the cam air vent tubes (the lines were so bad they snapped upon attempted removal) at the same time, and I noticed there was an issue with the canister between the Intake and the Throttle Body, the one the Cam Vent lines hook to. Inside the part that attaches to the intake port, there's a vacuum line that goes to the throttle body, with a 1 way rubber diaphragm on it about the size of a quarter. It's pink, and it covers a hole that connects to the cam vent tubes.

The one on mine was badly damaged, no longer doing whatever it was supposed to do. I took it down to the auto parts stores (all of them) no one could tell me what it was called or where to find one, other than a pick n pull n hope it's functional. Naturally, I left if off to see if it made a difference. Once everything was back together it started right up, ran better than it did when I bought it a year ago, and had all the power and responsiveness you'd expect a 2.8 to have. I took it back to the auto parts store to get codes cleared and read again, my car had a clean bill of health. No codes, no engine light, nothing. I figured it wasn't a critical part and went on with my life. Fast forward to this morning when I was driving my buddy to go pick his vehicle up from the shop, my check engine light came on a block away. They checked the CPU, it was reporting misfires on 3, 5, and then randomly. They cleared the codes just in case those were left over, tested again. Sure enough, I was misfiring still, despite the car running superb.

They told me they would have to run more diagnostics and charge me to find the problem. I told them I would come back it the check engine light came on again. I went home, and sure enough, it turned on again. I had to work tonight, so I drove it to work and while I was out on the road at work, just before the end of my shift, it started running worse than it ever had before, like I didn't even do any work to it. I parked it and now I'm stuck asking for help from those of you who have hopefully encountered similar issues and maybe have a solution!

It's Saturday night so no one is available to help me troubleshoot and I'm hoofing it 5 miles between my house and car. I need some actionable advice if you guys have any, I love you guys and we've never even been properly introduced!



Thanks!

Baeloro

Well, things aren't looking good for the old A4, it's no longer running well at all, the misfiring turned into what sounds like a blown engine. Not sure what I'll do now, tbh.