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Neal, Chevy Mechanic
Category: Chevy
Satisfied Customers: 8350
Experience:  Shop Owner and Mechanic on multiple makes.
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Chevrolet Monte Carlo LS: at idle my 1986 monte carlo luxury

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at idle my 1986 monte carlo luxury sport 305 runs great. when it idles for a while the service engine soon light comes on. then when i hit the gas, alot of light blueish to whitish smoke comes out the exhaust for a short while and the service engine soon light goes out. what causes this? its almost like there is not enough pressure to push the exhaust out at idle.

Hello I'm Neal and I am here to help resolve your issue. If I cannot help I will opt out and refer your question to another expert.


It is most likely just the idle air control valve that is bad and it is making it load up and get rich when idling. I would definitely try another IAC valve first. You can try just cleaning it but it does not always work.

Customer: replied 3 years ago.

i meant to add this to the original question but the codes it is pulling are 13 and 24. I don't know if this make a difference to your answer, but I have changed the O2 sensor twice with the same results. Now i will look up the IAC valve and see what this is about. Thanks

The 12 is just showing the system is working, the 24 is for the speed sensor. That is likely unrelated, usually the IAC will not cause a code, so I would still be looking at it first.
Neal and 2 other Chevy Specialists are ready to help you
Customer: replied 3 years ago.

code 13 not 12.

That is showing a bad o2 sensor or a wiring issue going to the sensor.
Customer: replied 3 years ago.

I was told that my carburetor does not have an IAC value.

I thought you had fuel injection which is what they typically had that year. Based on that additional information you will likely just need to have the carburetor rebuilt.
Customer: replied 3 years ago.

all 305 V8 engines for monte carlos were carburetors from 1986 to 1988. further, it is a recently rebuilt carburetor on my vehicle. l would like a refund please.

My mistake I misread your year or mixed it up somehow after reading your first post. Has it done this since before or after the carb was rebuilt?
Customer: replied 3 years ago.

It has done this since before the carb was rebuilt.

Does it smoke when you start it after sitting for a day or longer? How many miles on it?
Customer: replied 3 years ago.


Then it might just be bad valve guides, especially if it smokes after sitting. Based on all you have told me, this would seem to be the most likely problem.
Customer: replied 3 years ago.

I'm really not happy with this answer as it does not fully address my initial question. Once again, I would like a refund. I do not want another technician or my current technician to try to answer further.

Customer: replied 3 years ago.


Sorry I could not help. I will opt out.
Contact customer service to get your deposit back.

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