Cold Weather Idle - High/Low

M

msherman01

New Member
#1
#1
I've got a 2006 Corolla S, and I'm getting a check engine light. On first start, during cold mornings, the idle starts high, around 2200 rpm, then drops down to a very low 500 rpm, then back up to a high rpm and so forth. This happens until the engine is warmed up. At that point, the engine runs perfect. I have a check engine light and the code comes up P0171. I have changed the mass airflow sensor, and the upper O2 sensor. I'm being told that it could be a faulty fuel pressure regulator, or maybe even my fuel pump, however I'm doubtful with the fact that after the engine warms up, it runs great.
:( Any ideas?
 
Donabed Kopoian

Donabed Kopoian

6 Speed Master
#2
#2
Start checking for vacuum leaks around your Idle Air Control Solenoid. When the engine is cold, crab some Carburetor Cleaner and spray around vacuum lines. If the engine speeds up where you spray, you found your leak.

Don't go replacing things without diagnosing or it gets expensive quick. The upstream O2 was probably due anyway but with the others, if it ain't broke don't fix it.
 
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