So I'm not sure if I did something to cause this and not sure how far back in time this has been occurring.... but I was datalogging and noticed that after about a half hour of driving, the BLMs shoot up from 128-130 to upper 140s, sometimes as high as mid 150's. But only in certain BLM cells, mainly the lower to mid ones, like 3-7. From 11 and up, it holds steady at 128.

Before this starts happening, BLM's are around dead-nuts at 128-130 everywhere.

It also doesn't do this all the time... on certain runs it holds steady at 128-130 everywhere.

What also happens at the same time is at idle, I'll get these momentary "glitches" where the AFR on the WB shoots up to 16-17:1 and get this drop out and surge before it recovers. It'll idle rock solid at 14-14.5:1, and then this random split second glitch. I idle in open loop, so assuming these two issues are related, it can't be the O2 sensor itself.

I was thinking the ECM is glitching out or something, I swapped ECM's since it was easy to do but that didn't help.

It almost seems temperature related, but I'm at full operating temperature within about 5-10 min of driving. So what could be changing after 20-30 min that would cause this? Everything that is affected by temperature has already been at full operating temperature for a while.

In the meantime, Is there something in the calibration I should be looking at?

If there was some fueling issue, why wouldn't I see it everywhere? I.e., If something was causing the engine to go lean at all these BLM cells such that the BLM's shoot up to ~150, I would think that I'd see a steady lean out at idle as well (since I'm open loop idle). But, except for the momentary glitches, the AFR holds steady at 14-14.5:1.

Also my Power Enrich will easily get to the 12.5:1 that I commanded even when the high BLM's start occuring. Again, if there was some fueling issue, I'd expect the PE's to be lean as well.

For reference, I'm running S_AUJP V7. I've attached a datalog that shows what's going on.

 

The only thought is to look at IAT and CTS and see if they have sudden changes at the same time.

 

Yeah those look rock solid too.

 

I just swapped the WB and NB O2's to the opposite sides of the engine (NB was on the driver side). Tomorrow I'll drive the car into work and see what happens.

This will rule out a possible bad injector, spark plug, plug wire, or other things on the driver side of the engine.

If the problem continues, I know it's some more global issue affecting the entire engine.

 

Just to close this out in case this redundant thread doesn't get deleted... I think I found the issue.

https://www.thirdgen.org/forums/tpi/...rim-issue.html