pan6ther9

I have a 91 max se and it idles roughly until it warms up (usually 4-5 mins) Does anyone have any ideas i can try? Thanks!

DA-MAX

iTrader: (10)

fouled plug(s) and or an arching plug wire(s) could be the culprit! when my O2 sensor was bad the car had a kinda rough idle when I used to start it up in the morning.

brubenstein

What is the idle speed when cold? It should be ~1250 RPM.

pan6ther9

It idles at around 600 RPMs, then it will get really rough, drop down to 500, then occasionally stall.... Do you have any idea why it is idling so slow?

superdesi

I think the TB needs cleaning.

brubenstein

Not enough air is coming into the intake, so the mixture is rich and the idle low. Either deposits are blocking the flow, in the TB or AIV (air injection valve), or the AIV isn't doing what it's supposed to. The first thing to do is to make sure everything is clean, and then properly set the base idle speed (AIV disabled) when the engine is at full operating temp. If this doesn't cure things, then you have to begin more formal diagnostics to determine which components aren't functioning properly.

superdesi

When I start my car after its been sitting all night, it idles around 1450 ------ then after 12 seconds, drops to 1250.

Is that okay or abnormal?

brubenstein

My engine does the same thing, although the manual indicates 1250 as the initial speed. Warm idle speed is right, so I don't worry about it.