I have a 89 iroc 350 auto. When the engine is cold the car idles like crap, and the colder it gets outside the worse it idles. It sounds like it keeps cutting out and doesn't want to run, and i can't get it to rev past 1k. But after the engine has warmed up it idles fine. I checked the tps sensor and it was fine, i didn't get to the IAC but could that really be it? I am out of ideas at the moment. Any help will be appreciated greatly.

Thanks
Steve

 

Did you check the MAF connection? I acidentally disconnected it once and the next morning it ran similar to yours.

 

also check the temp sensor for the computer...it could be shot and not be adjusting for the cold weather

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350, Comp 262, Edelbrock Performer intake 600 cfm carb and exhaust, headers

 

MAF connection is good. Where is the temp sensor located, is that the same thing as the baro sensor?

 

Coolant Temp sensor is located directly below the throttle body at the front of the intake manifold. Actually there are two side by side. The one toward the passenger side is for the cold start injector and the one next to it toward the drivers side is the one you want to check. To check it at 40 degrees F. it should have about 7500 ohms of resistance, at 70 degrees it should have about 3400 ohms of resistance.
Also check the air temp sensor it should show the same amount of resistance and is located on the bottom of the plenum toward the rear(difficult to access) but there is a jumper wire coming out from under the plenum toward the rear with a connector in it. Just disconnect this connector to check the resistance.

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"84Z28/'91 305TPI comp cam flowmaster TB coolant bypass/shutoff valve to heater core MAT relocated Ram-Air(home-made) gutted air-box IROC ground effects/wheels GY245/50's 700R4 superior shift kit/ corvette servo(excellent shift kit BTW) Rebuilt engine and transplanted it myself. Love this engine!
LOW performance people should drive low performance vehicles!

[This message has been edited by 84IROC (edited October 29, 2000).]

[This message has been edited by 84IROC (edited October 29, 2000).]

[This message has been edited by 84IROC (edited October 29, 2000).]

 

SP,

In case it isn't exactly 40°F when you check the resistance of the sensor, you can get a close approximation from the following table:



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Later,
Vader
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"Make Me Bad"
Adobe Acrobat Reader 4.0

 

well it is not the coolant sensor, that was replaced this last spring. But i have a feeling it is the MAT sensor that is located on the rear part of the plenum, but i need to investigate further.

 

Steve,

A little cooler in the Northland these days?

Instead of digging the MAT sensor out from under the plenum, go buy a replacement. You'll be needing one later anyway - trust me. If you have ever wanted to move the MAT sensor for more accurate readings and better fuel enrichment, the easiest way is to leave the original sensor in place and install an auxilliary sensor in the intake air ducts. For about $30.00 in parts and a little of your time, the job can be complete. Check this link for details:

MAT Sensor.pdf

If you need the Reader to open the file, check the Adobe link below. If nothing else, check the article to see where the wiring is accessible to break into the system without removing the plenum.

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Later,
Vader
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"Make Me Bad"
Adobe Acrobat Reader 4.0

 

Yeah unfortunatly it is starting to get colder up here in the Northland. Thanks a lot for the info, i think i'll go that route instead of replacing the plenum sensor.

One question though, the picture in the file you showed me had a different air box, but none the less i should still put the sensor right by the outlet correct?

And after learning about the MAT sensor, it seems very probable that this is the problem.

Thanks again for the help
Steve