High idle in park and neutral

GINA TAYLOR

MEMBER
2003 CHEVROLET IMPALA
3.4L
6 CYL
4WD
AUTOMATIC
142,000 MILES

Hello, we are having issues with our car that are high idle park and neutral. The engine is overheating to high idle.

We had a mechanic come over and we replaced the following:

Throttle body (167.00)
Map sensor/master air flow
TPS three times ( showing incorrect voltage on scanner tool)
EGR valve
O-rings on fuel injectors
One fuel injector
Manifold gasket
Spark plugs
Spark plug wiring

There are no engine codes.
One time it shown multiple misfiring code we cleared it out and it went down and we turned off it idle high again in park. We checked for vacuum leaks (mechanic did) and there was none.

Please help we are are our wits end here!

5 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning.

Was this a new throttle body?

Did it contain the idle air control valve with it? Did your guy have a scan tool? If he did, he could command the idle air control valve open and closed to change the idle.

The PCM controls the idle based on many factors. It may also be the issue if it cannot be commanded up and down.

The TPS is showing high voltage due to the throttle plate not seating.

Roy

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Saturday, June 30th, 2018 AT 4:57 AM

GINA TAYLOR

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3 POSTS

It came with idle air. My husband does not have a scan tool.

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Saturday, June 30th, 2018 AT 9:05 PM

ASEMASTER6371

MECHANIC
52,797 POSTS

Was it a new throttle body?

You can rent a scan tool at some parts stores. You will need this to see if the idle air control is working. It could be a bad idle air control or a bad PCM.

Roy

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Sunday, July 1st, 2018 AT 4:48 AM

GINA TAYLOR

MEMBER
3 POSTS

Yes it was a new idle air control, new tps, and new throttle body all were installed. The car cranks and it starts off normal rpm and it jumps up to high after it gets warm.

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Sunday, July 1st, 2018 AT 11:52 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

At this point, you will need a advanced scan tool to monitor what is happening with the idle air control. Something is commanding the idle higher. Like I said before it may be the PCM that is the failure but needs to be confirmed.

Roy