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techspert, former shop owner
Category: Chevy
Satisfied Customers: 36
Experience:  Former ASE cert tech,shop owner of a diagnostic shop
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Car starts but wont hold rpms and idle..gas petal..idles fine

Resolved Question:

Car starts but won''t hold rpms and idle. If I hold my foot on the gas petal, I can put it in gear and it will run. Eventually it starts and idles fine. Its happened 2 times. Now it just happened and my son is stuck in Conn. I''m in NJ. Is there a sensor causing the problem that I can drive up and fix? I''m out of work and he just started with WWE apprenticeship.
Submitted: 8 years ago.
Category: Chevy
Expert:  techspert replied 8 years ago.
Hello! Is the service engine soon light coming on when the car is RUNNING? Does it run fine once you get it started? Does it ever stall when decelerating?
Customer: replied 8 years ago.
No Service engin light does not come on at all. The car runs fine once it starts. It has never stalled when decelerating. The first time it happened my son was home and I looked at the engince and took the cover off the top and just basically looked. I did look for a vacum line off, but found nothing. Then it just started and ran for about a year fine. The second time my son was at college in N Jersey and I drove up there and looked at it. Thats when I put it in gear with my foot holding down the gas pedal to maintain 1500 rpms. I drove it about a half a block and was getting ready to get it towed. I started it up and it ran fine. That was in November. This time its in Conn. and I'm probably to far away to help. My son has no mechanical ability and I'm kind of stuck because I'm out of work and he just started an intership with the WWE in Conn.-(which means he isn't making any money. Could it be a MAP or MAF sensor? Anyway thanks for the reply and your help.
Expert:  techspert replied 8 years ago.
Sounds like this could be an easy fix. There maybe excessive carbon build up in the throttle body.What happens is blow by gases are pulled through the PCV.Since carbon is a natural by-product of a combustion engine,it forms a carbon ring around the throttle plate.On a fuel injected car,the minimum air rate is preset at the factory.The incoming air comes through the throttle plate. The IAC or idle air control valve maintains a constant smooth idle. As carbon build up around the throttle plate,the opening for the air to get through gets smaller and smaller until the IAC can no longer control the idle and the car stalls.Kind of like plaque building up in your blood stream.You basiclly over come this by pressing down on the gas pedal,which in turn allows more air to flow in and keep the engine running. What you need to do is remove the air induction hose from the throttle body where the "butterfly" is. Have someone press down and the gas pedal to the floor.Take some gum cutter,2+2, which can be purchased at any parts store,and spray it on the inside of the throttle plate.It will be filthy! Take a rag and just run it around the inside to get as much black carbon as you can removed.After all that,reinstall the hose and start the car. It may not start right away at first since all the carbon and carb cleaner was sprayed into it. Then take it for a ride at about 35 mph at a fairly constant speed so the computer can relearn the idle. There may also be a problem with the MAF. LIGHTLY tap on it with the handle part of a screw driver with the engine running. If there is ANY change in the way the car idles-it's got a problem and will need to be relaced. Some of them can also be cleaned BUT they are very very delicate. There is a very thin wire inside of the sensor that accumulates dirt. This can also be cleaned with 2+2. BUT BE CAREFUL not to break the wire, or it;s no good.
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