06 Chevy Cobalt SS/SC 2.0L LSJ with ZZP stage 3 bolt ons (60# fuel injectors) and almost 220K miles.
I am looking for any help/guidance to solve an intermittent P0172 too rich bank 1 CEL. Initially, the P0172 started about 3 years ago after I did the ZZP stage 3 install. The P0172 occurred maybe once every 6 months - but now it is once every couple of weeks. It tends to happen when I am idling for extended time (stuck in traffic). It is somewhat repeatable if I have the A/C on after 10 or 15 min and idling in extended traffic. There is no misfiring, or difficulty starting engine, nor any performance issues.
Here is what I tried:
1) I looked at fuel trims, and they are indicating a rich (-14 LTFT) condition at idle.
2) I did a smoke test - and found a leak at the MAP sensor (under the fuel rail). I ordered a new MAP sensor. But - can this cause a rich condition? I would think this would cause a lean condition.
3) I initially replaced the MAF sensor, but it caused unstable 400 RPM surges at idle. The vendor is sending another MAF - although, it made me wonder if there is such a thing as the fuel trims need to be reset?? after changing out the MAF?
4) I did a fuel pressure test - and it reads the correct 58psi at the schrader valve with ignition on/engine on. I notice when the engine is turned off, the pressure steps down to 50psi - and I assume that is normal.

I haven't removed the injectors yet, but I intend to soon (I just ordered new injector insulators). I don't seem to have any symptoms that suggest an injector issue, so I've been putting that off.

Any suggestions?
Thx
IW

 

The Lean/Rich codes don't necessarily pertain to the car's AFR.

The LTFT's aren't great, but aren't terrible. It really sounds like you need a better tune - I'd reach out to ZZP and let them know the problems that you're having with their tune.