924Board.org

[924Kid]

I know this topic was discussed quite alot on the old board, but back then it wasn't a problem. When I first start my car, the idle is extremely low, only about 4-500 rpm. It runs very smooth and drives fine, just low rpm. It doesn't reach 900-950 rpm until close to operating temp.I've noticed that this problem is even worse during the winter. Any advice?

[larso]

sounds like the aux air valve isn't working, press on the throttle a little at idle, clears problem up? aux air is at fault if so.

[Dave]

I agree the Aux air valve could be stuck closed in the 924S it is located under the intake manifold. Or in you could try to play around with the idle screw on the throttle body

[924Kid]

I have more stupid questions. I took your advice about the auxillary air regulator and did some reading in the Haynes manual. The manual says that one reason the valve may not work is if it is not getting enough voltage from the battery. Well, I also notice my alternator warning light coming on when I start the car, but I had the battery & alternator both replaced about a year and a half ago. So is it my charging system thats actually causing trouble?? I also ask, because the manual says that the regulator also ties in with the fuel pump relay. The fuse for my fuel pump blew not very long ago. Please help!

[-nick]

your alternator light is coming on because the engine is spinning so slowly. at such low rpm's the alternator isn't spinning fast enough to supply enough voltage to the battery.

it's not the other way around, the engine isn't spinning slowly because of your alternator/charging system. you can definately cross that off.

the aux. air valves are definately not immune to failure. there is simple test to find out if it is working mechanically first, where you take off the valve:

1. put in the freezer for a while and the look through it. the hole should be almost all the way open (in the car, this would give you a higher idle when it's cold, it's just like turning your idle up high until the car warms up).

2. let it come back to room temp (warm), the hole should be almost closed. this is analogous to turning your idle screw down, ie- less airflow, slower idle.

that's how the valve works. it just by-passes the throttle body. it would be the same as if you just gave it a little gas at the pedal to keep the idle up until it warmed up.

if this test turns out OK, then check into the electrical supply coming to it with a multimeter. i would probably turn the idle up to where it should be before doing to electrical test when cold.

regards
-nick