I've got a weird issue with my RA. It started throwing the P0171 without any noticeable changes. Then the idle starting becoming irregular at times, dropped really low to the point it almost stalls (4-500 rpm), climbs to 700, climbs to 900, goes back to 500... Seems to me this happens only with a hot engine.

3 days ago I was in traffic and my revs jumped to 2500 and stayed there, like a had a posessed 2step. Revving it didn't change a thing, only when I eventually clutched to move forward, it went back to 5-7-900 rpms jumps.

I'm clueless. I thought at first that injectors could be clogged, but high rpm operation isn't changed at all. I can't see how it could make the engine rev on it's own.

Any leads?

 

Search is your friend, it will lead you to the TSB that covered this issue.

 

Might be the MAF if it's readings are whacked out it's possible it might make the car high idle... just a guess though. You will have to start knocking these off the list.

•The MAF (Mass Air Flow) Sensor is dirty or faulty
•There could be a vacuum leak downstream of the MAF sensor
•Possible cracked vacuum or PCV line/connection
•Faulty or stuck open PCV valve
•Failed or faulty oxygen sensor (bank 1, sensor 1)
•Sticking/plugged or failed fuel injector
•Low fuel pressure (possible plugged/dirty fuel filter!)
•Exhaust leak between engine and first oxygen sensor

 

Still can't find the thread you are talking about... Damn that search tool isn't my best friend.

Cleaned the MAF sensor with brake cleaner recently, didn't notice any difference. Anyone have the bench testing procedure?

I just received my fuel pressure gauge, but won't have my new fuel rail for a few weeks, and plan on doing both installs at the same time. Fuel delivery is the next on my mod list, like cleaning injectors/changing the fuel filter.

I like the o2 sensor theory, they must be cheap also so I'm thinking it could be worth trying.

Meanwhile, keep the ideas flowing!

 

I like to use google search I can usally find a thread faster than searching here..