The used chain tensioner I had swapped in went out very quickly. Also, my fuel pump randomly stopped working leaving me stranded a few times. If I cycle the key it would eventually work. I replaced the pump.
I swapped out my Bank 2 chain tensioner and upon start up I have constant misfires on Cly 1&3 as well as the random misfire code. It idles extremely rough and eventually stalls. I can watch them rack up in measuring block 15. I touched nothing on that side of the engine.
I’ve done the following;
Swapped around plugs, coils, and injectors
Compression test looks okay - 120ish cold
Unplugged Front O2’s
Wires are all good from coils and injectors to ECU
I hooked up a gauge to test fuel pressure and it was 0. So my attention quickly turned to this. Not sure if it is the cause for my misfires but I need fuel pressure before I can move on.
The pump is new (Delphi from RockAuto but came with Audi rings and VDO stamped on it so I lucked out there).
Fuel pump relay is new
Fuel filter is about a year old (KYG Audi)
Shot all the wires and all I found was the ECU not grounding the relay 100% of the time. I’ve seen many posts about this grounding issue but nobody has followed up with a fix. As far as I know the pump should prime every time the ignition is cycled.
I pulled the cover off the relay to manually trigger the pump. I started testing pressure from the pump on and discovered that the fuel pressure regulator was dumping all pressure back into the tank from the forward center fuel line on the filter. I did some digging and found nothing like this mentioned anywhere. A new filter is on order and I’ll be able to continue troubleshooting in a couple days.
I’ll report back with any progress. I think I’m on the right track but feel free to keep me between the lines.