Hey guys - so last week I returned from a 300-mile road trip and shortly afterwards I started getting an erratic idle and intermittent stalling when coming to a stop. The engine is also feels like it's choking under hard acceleration and causing the car to buck. I also get some momentary hesitation just when going through the gears and accelerating normally.

I got a solid CEL during the drive when the car first stalled, with two codes:

- P0172 System Too Rich Bank 1
- P0335 (CKP) sensor circuit malfunction


The day after I started seeing the problems, I did the following maintenance:

- replaced plugs
- cleaned MAF
- cleaned ESS (first time ever - it was dirty)
- cleaned air filter
- reset NVRAM
* oil change was done just prior to my trip

I have the BHR ignition, which I just replaced about two years ago. I also have the BHR midpipe with the ceramic cat, which was installed a couple years ago as well. I'm suspecting the cat may already be toast, but I thought I'd be seeing misfires if this was the case.

The car drove well during the first drive after the work I did on it, so I cleared the codes and they haven't come back yet. But I'm still seeing an intermittent idle problem. Most noticeably, when I first start the car, the idle will sometimes bounce up and down rapidly, or it will just be erratic. Also, I'm still not always getting that immediate acceleration when I hit the gas after shifting and the car seems to hesitate under hard acceleration. No more stalling though, yet.

As always, any suggestions are greatly appreciated!

 

Do you have a way of monitoring your fuel trims?

 

I do run DashCommand and noticed before I changed the plugs and everything else, AFR was on the rich side at idle. Now it's right around 15:1. I haven't logged the long/short term fuel trim yet though. I can get these numbers, but honestly I'm not 100% what I'm looking for.