Hi all,
My idle slowly went south from about 700 to about 400-450 over about a week's time. I've adjusted it back up to 700 and everything runs smooth but now what? It dropped for a reason.

Where should I start looking for the reason it dropped in the first place?

Any tips or previous experience would be greatly appreciated.

Thanks,
Joel



[Modified by 91SE, 3:51 AM 2/18/2003]

 

The screen on the IACV (idle air control valve) could be clogging up. Mine looked like a rubber disk when I pulled the IACV off. You could also have EGR ports that are clogging up. A week's time is rather quick though, but if the passages and screen were borderline, it's possible.

 

Clogged EGR ports won't affect the idle. The idle air bleed port could be partially clogged. (The passage behind the idle screw.)

 

Good point about the air bypass screw.

EGR can affect idle if one or more ports are clogged and the valve is stuck open though.

 

If the EGR valve is stuck open that will screw up the idle for sure. More if the ports are clean. One way to check for clogged EGR ports is to apply vacuum to the EGR valve. The engine should stall if it's working properly. If it has clogged ports, it will cause the idle to drop slightly.