I need some good advice in order to nail down the problem.
Little background on what's happening with my 2001 VW Passat Wagon 1.8t (AWM)
I've been driving for a few months with the engine light - error P0171 - Bank 1 system too lean. Since I didn't find anything wrong with any of the hoses I changed the pre-cat O2 sensor hoping that would fix the issue. It did not. I drove for a few months with the light on but without any obvious issues. Last week I saw that the Breather Hose Connector (3-way hose) had a pretty big hole. I changed this connector and while it was off I tried to scrape some of the gunk out of the hoses (could this gunk have something to do with the upcoming issues?). Again, I hoped this may finally keep the engine light from coming back on. Two days later the engine light came back on, three days later the engine light started flashing and the car shudders. Now, I'm getting in addition to P0171 also P0201 - Cylinder 1 Injector Circuit Malfunction and P0300 – Random/Multiple Cylinder Misfire Detected along with P0301, P0302, and P0303 for the individual cylinders.
This is what I did so far
1. Found oil on the spark plugs, cleaned the area and replaced the spark plugs
2. Pulled the ignition coils while idling, Cylinder 1 (front) did not cause any change with the coil pulled off.
3. I swapped the coils around – all coils seem to work (they are only 20k miles old anyway)
4. Measured voltage and resistance on the fuel injectors. Voltage measured while idling, Ohm with engine off
Cylinder 1 (front) Cyl 2 Cyl 3 Cyl4
Voltage 10.3 volt 0.2 0.2 0.2
Ohm Nothing or infinity 13.2 ohm 13.2 ohm Nothing or infinity
This is what I’m planning to do next
1. Check the cylinder compression
2. Replace the valve cover gasket (this certainly needs to be done, but has nothing to do with the above error codes, or? Could the valve cover gasket be the reason for any of the above error codes?)
3. Replace the fuel injector on Cylinder 1 (Do you guys agree that this one is most likely broken? Any of the others? Or is the issue rather in the wiring or PCM?)
Any recommendations on getting this fixed? Thanks for your help