YACT: Funny idling

[archcommus]

1992 Sable

Awhile back car started idling a little too low, around 500-600 RPM instead of the usual 750. However it didn't stall so it wasn't too much of a problem. Then it started stalling only the first time I started it for the day (in the early morning), then after I started it a second time it wouldn't stall again all day. I found I could avoid the first start stalling by going into reverse immediately after starting the engine, and then going into overdrive and going.

Recently now, it is sometimes idling too high. Sometimes when I stop it'll idle around 1000 RPM which causes me to jolt a bit forward when I let off the brake. When I got to work this morning and put it in park, it went up to 1700 RPM and stayed there until I turned the engine off.

I was initially thinking I could just adjust the IAC valve, but since sometimes it idles high and sometimes it idles low I doubt that's the cause. Any ideas?

 

[iamwiz82]

The IAC could be sticking. Get some Throttle Body/Carb cleaner and take it off and clean it. I had that same kind of issue with one Jeep.

 

[AMCRambler]

Oxygen sensor perhaps? Mass air flow sensor(if that year even had one)?

 

[Zysoclaplem]

When my IAC in my Volvo began to go, that's what it did initially. Replaced it, and it went away.

 

[archcommus]

Is there any way to tell initially if the IAC is bad or just dirty? How much can those run for?

 

[Demon-Xanth]

Try just cleaning the throttle body.

 

[archcommus]

Originally posted by: Demon-Xanth
Try just cleaning the throttle body.

Would this be easier than removing and cleaning the IAC valve? Unfortunately I don't quite feel confident enough to do any of these things and I'm sure I'd pay far too much for it at a shop.

 

[Demon-Xanth]

Originally posted by: archcommus

Originally posted by: Demon-Xanth
Try just cleaning the throttle body.

Would this be easier than removing and cleaning the IAC valve? Unfortunately I don't quite feel confident enough to do any of these things and I'm sure I'd pay far too much for it at a shop.

Use a tooth brush and some carb cleaner. For most cars all you need to do is remove a hose clamp and pull a tube off.

 

[Quasmo]

Oldsmoboat's law DEFINATELY applies here.

 

[archcommus]

Originally posted by: Demon-Xanth

Originally posted by: archcommus

Originally posted by: Demon-Xanth
Try just cleaning the throttle body.

Would this be easier than removing and cleaning the IAC valve? Unfortunately I don't quite feel confident enough to do any of these things and I'm sure I'd pay far too much for it at a shop.

Use a tooth brush and some carb cleaner. For most cars all you need to do is remove a hose clamp and pull a tube off.

Hmm alright, thanks. I'll see if I can get some detailed instructions from the guys over at the Taurus Car Club. Unless of course anyone here is familiar with early 90s Fords/Mercurys.

 

[JeffreyLebowski]

Originally posted by: archcommus
Is there any way to tell initially if the IAC is bad or just dirty? How much can those run for?

IAC's are cheap, go to your local parts store and get one. I picked up one for my Trans Am a year ago for like $20 if that much.
If that doesn't do it, then you either have a bad MAF, the computer is acting up or you have a vacuum leak somewhere.