P0171

[MGargano]

I swapped my 1ZZ throttle body back to the stock one, and ever since, I'm getting CEL P0171 when I idle for about 5 minutes. Aside from the TB, I haven't changed anything that I think would be causing this. Anyone know of any 'problem' areas to check for a fix to this?

[AlexNet0]

unplug the battery negative terminal, turn the headlight stalk on, and wait overnight before re-connecting the battery.

[MGargano]

The car runs rough (in cycles) at idle. It'll idle smooth, then go through a wave of roughness for a few seconds, then back to smooth, again and again. It's worse with the a/c on. The car has less than 3,000 miles on it, so I don't think it's clogged injectors or MAF or bad o2 sensor...

[AlexNet0]

did you read my post?

[MGargano]

did you read my post?

Yes, sorry I was posting my follow-up when you posted your reply. I pulled the battery cable and will check again tomorrow.

[seth_man]

P0171 is a lean condition. which means your getting not enough fuel or un-metered air into the engine after the mass air flow sensor. double check everything you touched make sure hoses are connected and not broken and i would pull that TB off again and check the gasket. just pulling the battery to clear the code wont repair the problem.

[AlexNet0]

P0171 is a lean condition. which means your getting not enough fuel or un-metered air into the engine after the mass air flow sensor. double check everything you touched make sure hoses are connected and not broken and i would pull that TB off again and check the gasket. just pulling the battery to clear the code wont repair the problem.

have you been following the TB threads? If there really is a problem, then the code will come back, if it simply needs to re-learn the stock Tb again, then it wont. No need to rip everything apart again when there is no certainty there is another problem.

One step at a time.

[MGargano]

I'm hoping it's just the ECU needing to relearn the stock TB again

[MGargano]

No such luck. The car idled smoother today than it did before I disconnected the battery, but still rougher than normal. And the CEL came back at idle after driving a few miles. Ideas?

[jkuchta]

Look for air leaks....thats more than likely the cause of your problem.

[MGargano]

Look for air leaks....thats more than likely the cause of your problem.

Any usual suspects for what/where air might be leaking?

[MGargano]

I switched back to the 1ZZ TB w/ chip swap and adjusted the idle screw... still getting P0171 but the idle doesn't seem rough now.

[AlexNet0]

I guess make sure that the vacuum lines are all reconnected, I accidentally pulled the vent off of the valve cover once.

[MGargano]

The engine's idling smoothly now, but I'm still getting CEL P0171... where should I be looking for a possible air leak?

[MGargano]

Found it! The valve on the Husky filter I'm using as an oil catch can is for shit... leaks air like crazy.