Rough Idle, P0171, Tried Everything
 

2.3L 4-Cyl tried everything.
Started it up a couple weeks ago. Slight pop, smoked a tad, and then was fine. Since that time it has run really rough and Check Engine Light came on. P0171, (Lean) and pending P0113, (Intake air temp sensor circuit high).
So, to remedy, I have:
- Cleaned MAF,
- Replaced PCV,
- Pressure tested/inspected PCV Valve hose that goes up back to intake manifold. Held pressure.
- Tried the brake clean technique for leaks, made it backfire a tad
- Cleaned IAC
Goes 75-80 no problem, never stalled - yet.
I am at a loss.
First post on the forum. However, deeply indebted as this forum has helped in so many other issues.
Thanks for any insight....

Re: Rough Idle, P0171, Tried Everything
 

"Lean" can be lean from lack of fuel or excess O2, or can be lean interpreted by O2 in the exhaust because of misfire. Misfire leaves the O2:fuel mix intact, so there are O2's floating by the sensor.
A 'pop' can lead to hoses popping off their 'spot' or splitting, thus leaking extra air into the engine that is not measured by the MAF, if you have a MAF. Extra air can cause misfire.
I'd check the vacuum in the intake with the engine running at idle, and also take a look at all vacuum hoses, and even the EGR diaphragm if you have one.
The Lima first had a 'backfire' valve on the PCV line that was spring loaded, and could/would pop out of place on occasion. That made the idle terrible. Once figured out, I knew what was wrong when it happened. I don't think they use that any more.
I'd suggest checking for leaks. If the temp sensor is cooked, they don't cost a lot to replace. It should be screwed into the intake manifold, and easily accessible.
tom

Re: Rough Idle, P0171, Tried Everything
 

Thanks Tom, Appreciate the input. Will check and follow up...