Stumped by obd2 check engine faults. Could use some help!

[RenaissanceMan]

Update 4/19:

Exhaust gaskets replaced and exhaust leak eliminated. Also ended up replacing the ECS (engine coolant temp) sensor since someone in another forum I posted in brought up a great point about engine temps. Still getting the same exact adaptation faults though.

[RenaissanceMan]

Any opinion of whether it runs better or worse while the lambda integrator is pegged?


At this point unless you have a wideband to show the fueling is somehow way off, I'd say it has to be the ECU.

Car definitely runs better while the lambda integrator is pegged. What would that imply?

[Northern]

If it runs better while it's trying to add a ton of fuel, maybe it genuinely is running really lean?

Tune, vacuum leak post MAF, fueling issue (which you already ruled a ton of stuff for) and MAF (which you replaced?)

[RenaissanceMan]

SUCCESS!!!

Ok, so apparently the problem was the exhaust leak after all. When I last posted it looked as if the leak fix didn't fix it, but then I discovered that I accidentally swapped the O2 sensor connectors the last time I disconnected them to continuity/voltage test. Swapped the connectors back and no more faults. I'm honestly surprised that is what it was, but I have to assume that the leak was in close enough proximity to the O2 sensors to confuse them?? Regardless, I'm just so relieved I finally have this fixed. Huge thanks to Northern for sticking with me in this thread trying to help! I learned a TON going through this diagnostic process.

[Northern]

I'm just glad you found the issue!

[RenaissanceMan]

Reporting back after super frustrating development. Check engine light is back, but this time it's only interpreting a lean condition on bank 2. Bank 1 appears to be behaving normally according to data. I went ahead and replaced the fuel injectors with brand new, found and fixed a pinhole leak in the exhaust header, and also smoke tested the intake and exhaust again repeatedly. I don't know what else I can replace besides spark plugs? I don't have any idea what else it could be. Anyone have any more ideas??? I'm about ready to light this car on fire. :(

[RenaissanceMan]

Finally got it figured out. Fix ended up being repairing the pre-O2 sensor exhaust header leak. However, faults continued until I cleared adaptations. Apparently since the LTFTs were so out of whack ECU was still throwing codes and I guess not going into closed loop. Now all is well.

[RenaissanceMan]

So, don't mean to beat this thread to death, but in the week that followed my last post, the check engine lights came back yet again! I got to the point where I ran out of things I could do, so I finally decided to try a different ECU. Been driving the car for weeks now with no more issues. Finally explains why the faults kept coming and going. There was something awry with the computer that was causing intermittent faults. I think I can now finally share that the problem is really and truly resolved.

[Victell]

So, don't mean to beat this thread to death...

Coming back and updating a thread with the solution makes forums and message boards work better. Much appreciated.

[Bmrlvr4lfe]

Northern, you rock! Thank you for sharing t time and expertise!
RenaissanceMan, thanks for the detail and follow up on fixes as your progress and final fix.

This thread helped me and will help a ton of people for years to come!

Thanks again!!🙌🏻🙌🏻