P1222 but CEL goes off if I punch the throttle.

[ecalder]

Hey guys hope everyone is doing well!

I'm dealing with a weird CEL. I get the P1222 code when I do the stomp test but the CEL kind of comes on and off. At first I thought it was random then I noticed the car would almost stutter coming off of a dead stop and that's when it would come on. Then it would go days without coming on. Today I picked it up from the "inspection" and it came back on again and I noticed that if I punched the throttle it would disappear immediately. Then a few seconds sometimes minutes later it would come back on.

Any ideas? I know P1222 is pretty broad but maybe the intermittent behavior can help narrow it down? I have a DE this weekend and I don't want to flog it if it is something serious. If its the TPS or something then I'm not so worried about it.

Ideas?

Thanks a million.

[kamotors]

big fuel injectors without a chip, a bad o2 sensor or bad AFM are the usual causes. My car did that when I had big fuel injectors and no chip. I would just touch the throttle and then it woud go out.

[ecalder]

Thanks man I think I've narrowed down to bad O2 sensor. Basically when I start the car cold the revs stay at a constant 1,100ish and then as soon as what I assume is "closed loop" kicks in the revs start varying and the CEL turns on. If I remember correctly the ECU doesn't consider O2 sensor input during "open loop" which leads me to believe that is the problem. Regardless, I didn't actually do anything to the O2 sensor last night and I've driven about 50 miles today without a CEL. I figure my O2 sensor is on its way out I guess.

Thanks again.

[jlevie]

That is most likely a combination of an aged O2 sensor and intake leaks. The O2 sensor is a scheduled maintenance item with a replacement interval of 100k. Which is something a lot of folks don't seem to understand. Actions at this point would be to replace the O2 sensor, have a smoke test run, and fix the leaks the test reveals. There are other possibilities, but until those actions are taken it makes no sense to look further.

[ecalder]

Great, thanks for the tips. I'll install my new sensor tomorrow. I checked for leaks with carb cleaner today, didn't hear any changes in the idle, but I also realize that's not a guaranteed way to find a leak.

Later.

[ecalder]

Well the sensor made a pretty big difference. I swapped it out and ran four track session with no CEL although I'm still seeing a varying idle (from about 1,100 to 1,200). I'd love to see it back down at 800rpm again.

I'll start going through all of the troubleshooting possibilities and report back. My buddy says its the icv but I've done all of the tests in the Bentley manual and it passed with flying colors!