1996 3100 weird idle (just got weirder 22 Dec)

[white4d96]

My car idles pretty steady at around 800rpm normally. I warmed the car up today and it would randomly rev up to 1100 for a second and drop back down. Didn't seem to be affected by temp. Is this normal or could it be an IAC issue?

Edited December 22, 2010 by white4d96

[AL]

How cold was it?

[Jonpro03]

It's probably ok, just took a sec for the computer to adjust the IAC valve.

[white4d96]

Not really cold, I think it was above freezing.

 

Hasn't done it since so I'll just chalk it up as a fluke.

[white4d96]

Yesterday, my idle got really weird. When I cold-started my car, it acted like at first it wasn't firing on all cylinders. Whole car was shaking and bucking and whatnot. Then the idle kept dropping like a rock and trying to die out, even aftyer it started firing on all six holes. I had to manually maintain the idle at 1200rpm, then all of a sudden it shot up to 2k and even if I lifted it held there for about a minute. Once it got warm it was fine.

[tornado_735]

LIM gaskets about to puke.

[white4d96]

Great...time to start saving for a gasket kit. Or maybe just cave and do a top swap while I'm at it...

[tornado_735]

NOW you're thinking

[white4d96]

So do you recommend I don't drive the car for now? Or should I just baby it if/when I do drive it? Last thing I need is coolant wiping out my bottom end or hydrolocking my motor.

[Addicted to eaton]

my not check for vac leaks. Pull the Map sensor wire see if it makes it worse or better. check for other stuff be for gaskets.

[AWeb80]

Could be the icm on the way out. Long shot, but ya never know.

[BXX]

Get a scanner one there and pull codes. Sounds like the crank sensor or cam sensor is on its way out.

[Wheels]

My car idles pretty steady at around 800rpm normally. I warmed the car up today and it would randomly rev up to 1100 for a second and drop back down. Didn't seem to be affected by temp. Is this normal or could it be an IAC issue?

 

My car does that every once in a while but i figured that was normal. It hasn't done that lately though. I'm not sure of the other problem you're starting to have...but i agree with BXX, it might be best to check the codes.

[BXX]

And before you ask, just because the SES light isnt lit up, doesnt mean you dont have codes.

 

Odds are you have some pending codes in there from the issue. Most codes wont hard set the SES light unless they are considered emission codes, i.e. meaning the issue will cause emissions to be raised by more than 150%

[white4d96]

Can any scan tool pull pending codes?

[Addicted to eaton]

any that is for the car. yes.

[white4d96]

Okay, because I wasn't able to pull anything pending with a scan from Autozone. But I've started the car 5 times cold since that incident and no issues. I'll just keep an eye on things for now.

[dodgethis]

White,

 

I was going to say mine will bounce up and down for a little bit until i give it gas right when i restart the car after i have let it sit for about 10 minutes. IAC could also be an option.