Idle

[Dan48382]

I'm a new convert to Saturn. Out of need of a vehicle last winter I came across a 1995 SC2 (manual 5 speed) with 186,000 miles. The car was in great condition (the engine is understandably tired...uses oil).

I've spent countless hours going through these great Forums, benefiting from everyone's posts. THANKS!

I've been working on it a bit, the idle was all over the place, some cleaner took care of that. The temperature gauge never went much past cold so I replaced the thermostat and O2 sensor and the millage went from 27 to 32 mpg.

I'm not an expert on cars, but I've done my fair share of repairs. With all of these sensors.....things have changed.

This is my problem. When I put in the clutch and coast the idle drops way down to about 300 rpm if it doesn't stall completely. Once the car comes to a complete stop the Idle returns to about 700 rpm (steady no wavering). Where do I start the hunt for the FIX.

[wolfman]

This assumes the speedometer is actually working, and that the SES (Service Engine Soon) light is NOT on.

The IAC valve is sticking OR the TPS (Throttle Position Sensor) is bad.

To test the TPS. With the car warmed up and idling, rap on the side of the TPS with the plastic handle of a screw driver. If the idle speed alters AT ALL, REPLACE the TPS. If it does not, the IAC (Idle Air Control) valve sounds like it is sticking SHUT. Remove and clean the IAC valve and its pasage, replace the "O" ring. If this does not improve things, the IAC valave probably needs to be replaced, or there may be a problem with its electrical connector.

[Dan48382]

Thanks for the help on where to look. The speedometer is working and the Service Engine Soon light has never come on. So I'll start with your suggestions. Thanks again.

[sps SOHC]

I have the same problem except reversed! Sometimes when I'm coming to a stop and push in the clutch the rpms will climb steadily to 1700 or so and stay there. I have to blip the throttle once or twice and it usually falls back down to 800ish.

[Dan48382]

Next time I'm out and have room, I'll have to get going in reverse to see if mind does what your's does while going forward (LOL). Hope we both can resolve this.

[Dan48382]

A huge THANKS to Wolfman. This last weekend I checked it out. I can see why you said to use the plastic end of a screwdriver, there wasn't enough room to get in a good swing with my hammer . Anyhow while checking the location of the IAC I noticed that the plate in the throttle body seemed to be sticking a little.

I picked up some CRC air intake cleaner and got the area around the IAC and the Plate as best as I could.

Now when I put in the clutch the Idle slowly drops to about 900 and no further (about 100 rpm faster than before).

Thanks again for the help