I have a 1996 Monte Carlo that will idle aroung 3000 rpm on start up and will not come down unless you turn engine off and re-start. I have noticed even then, if you are sitting at a stoplight or something that it will surge every once in a while. I can access the OBD, but there are no codes being thrown out.

Any ideas?

 

[align=center]Hi SpaceAce & Welcome to the MCF Family.[/align][align=center](Good MCF Name: )[/align][align=center][/align][align=center]If it is not throwing any codes I[/align][align=center]suspect it could be a faulty idle speedsensor. [/align][align=center][/align][align=center]I would also check your `Cat to made sure it is not clogging : ([/align][align=center]Also I would clean your Mass Airflow sensor.[/align][align=center][:-][/align][align=center]Check back later 2 see what some of our expert members[/align][align=center]post about your problem.[/align][align=center][/align][align=center]Have you ever used a product called Sea Foam ?[/align][align=center]It cleans your system. To read about it, just do a[/align][align=center]Googles Search & type in > Sea Foam[/align][align=center]Click on below link[/align][align=center]Sea Foam
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Is the Idle Speed Motor the same as the Throttle Postition Sensor, Idle Air Control Valve or Vehicle Speed Sensor? Maybe it is none of the above mentioned. I just wanted to know because sometimes they are called different things and I can't seem to find anything called the Idle Speed Motor in my breakdown manual.

Thanks

 

the idle air control valve is what 'Space mentioned i believe.

my first thought was a clogged kitty under the car (i call the catalytic converter a kitty sometimes).

does it feel like it's weak on power or anything? does it surge any going down the road?

3000 rpms is too high for a start... you definitly need to look into the problem.

lots of times a clogged cat won't set off a check engine light.. i think the idle control vavle would, so i'm leaning towards the clogged cat.

 

Thanks Guys, I will look into both. One more thing though, if the Cat was clogging why would the the re-start bring the idle down [even though it is still a little high (~2000 rpm) and still won't kick down after warmup].

 

I don't know the answer to that question.... I just know that weird and crazy mess happens when cats clog. There are, however, other possiblities, as 'Space mentioned.

 

check this in this order

1. air temp sensor- its in the intake tube
2. AIC (idle air control) valve- its on the back of the throttle body
3. TPS (throttle position sensor)
4. vacuum leak
5. manifold vacuum sensor- its a black box on the back of the intake

if any are clogged or defective let us know