Another note regarding lean condition: At idle, manifold vacuum is greatest since the throttle plate is closed. Vacuum is reduced with throttle open, like driving on the highway. So, sometimes driving on the highway will show proper O2 readings even if at idle the signal goes lean, depending how bad the vacuum leak is. Maybe check the O2 trends on the highway too. Safety first, this should be done with two people so the driver is not distracted.

 

The Walker sensor arrived earlier than expected, so I installed it and it seems to have resolved the issue. Both upstream sensors are moving from rich to lean as they should, and no code is being thrown.

It looks like some combination of dead on arrival sensors and/or ones I killed with the propane torch test. Not sure I'll be using that diagnostic again.

STFT and LTFT are reading different values now, but I want to get some drive time in before I dig back into what they are telling us.

Also, I did the "option b" ABS repair yesterday, and it resolved the errors we were seeing intermittently (albeit more frequently lately) that tripped a code. Seems to have addressed the issue.

These fixes should get us through our annual state safety inspection.

Thanks a ton everyone. Not sure I would have stuck with this through to the fix if it wasn't for your guidance and support.

 

I doubt the bench test killed any sensors.

It is common for STFT and LTFT values to be different. Over time, the LTFT will adjust (hence the name). You can also reset adaptive values if you don't want to wait. What LTFT numbers are you seeing?

 

Here's a screen shot I took, for example:


Not sure if any of this is interesting?

 

No new fuel trim data points, work has been busy, but I wanted to report that the disco passed its state safety and emissions inspection and is error code free.

 

Great news!