Pontiac Montana fast idle warm

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whitetr
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Joined: Thu Oct 01, 2015 3:13 pm

Pontiac Montana fast idle warm

Unread post by whitetr » Thu Oct 01, 2015 3:21 pm

I have a 2003 Montana with 220,000 miles. When the engine warms up the idle will increase from a normal of about 600 rpm to 1500 or more. The transmission shifts at over 3000 rpm, transmission was rebuilt at 190,000 miles problem was there prior. While sitting at a light it may reduce rpms to normal or not. I have had the throttle body cleaned, checked for vacuum leaks none found, replaced the TPS. I have checked the wiring harness for issues and found no issues.

 

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carriedi
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Location: Oregon

Re: Pontiac Montana fast idle warm

Unread post by carriedi » Fri Oct 02, 2015 2:40 am

Is the check engine light on?

If the check engine light is on it will affect the transmission shifts.

for the idle problem I would connect to a scanner and look at you idle air counts, fuel trims and even though you replaced the TPS, I would look at that reading too.

There have been times when the pcm was bad causing problems like this too but you want to make sure everything else is good first.

Have you tried a hard reset for the computer?
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whitetr
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Joined: Thu Oct 01, 2015 3:13 pm

Re: Pontiac Montana fast idle warm

Unread post by whitetr » Fri Oct 02, 2015 9:22 am

The check engine light is not on.
I have a scanner so I will take a look the items you suggested.
How do you do a hard reset on the computer?

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carriedi
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Location: Oregon

Re: Pontiac Montana fast idle warm

Unread post by carriedi » Fri Oct 02, 2015 8:05 pm

You can do a hard reset by disconnecting your battery ground cable.
here is a video
https://www.youtube.com/watch?v=W_7Ehz1rdY0

afterwards you will need to drive it around for a while for the computer to relearn everything
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