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gmc envoy_slt
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Discussion Starter · #1 · (Edited)
Hey guys this is my first post so please bear with me.

I have a 2003 envoy SLT 4x4 and randomly it will start idling high at around 1,000 RMPS.

Before when this happened it gave a code (dont remember what the code was) and the guy that scanned the code at advance auto parts said it was the sensor on the air intake. I replaced that and it still happened.

Then I started doing some research and figured out it was probably because my Envoy was running too cool. It would stay a little above the halfway mark between 100 and 210. So I changed the thermostat (bought at advance auto parts) and now it is staying between the first notch under half and the second notch ( if anyone can tell me how to upload a picture I will)

It is not all the time either. Just happens randomly when driving. It wont do it for weeks and then it will start doing it for like 10-20 minutes and then next time I come to a stop I will notice it stopped doing it. Sometimes it doesnt stop doing it before I get to where I am going also.

Do you think the temp is still too low?

What else should I check for to fix this high idling issue?

Thank you guys in advance!
 

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2004 gmc envoy_slt
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Since it is intermittent, it will be hard to track down. High idle can sometimes be caused by a vacuum leak or a dirty throttle body. The intake manifold bolts have been known to loosen causing leaks in that area. Cleaning the throttle body should be a regular maintenance task ( about once a year). Look into these two things to address your problem.

Get yourself a code reader or invest in a scan tool. The Torque app for Iphone or android can give you a lot of information about the engine. BTW, the temp gauge should be at center straight up (210) or just to the left. A scan tool will read the actual temperature, and this will normally be about 195 degrees.
 

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gmc envoy_slt
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Discussion Starter · #3 · (Edited)
Since it is intermittent, it will be hard to track down. High idle can sometimes be caused by a vacuum leak or a dirty throttle body. The intake manifold bolts have been known to loosen causing leaks in that area. Cleaning the throttle body should be a regular maintenance task ( about once a year). Look into these two things to address your problem.

Get yourself a code reader or invest in a scan tool. The Torque app for Iphone or android can give you a lot of information about the engine. BTW, the temp gauge should be at center straight up (210) or just to the left. A scan tool will read the actual temperature, and this will normally be about 195 degrees.
Thank you for the reply

I can check for a vacuum leak.

Also I did just clean the throttle body about a month ago so that is probably not the issue. Also I just replaced the valve cover gasket and in doing so I had to take the bolts off of the intake manifold. So they all should still be tight.

It is just to the left of 210. Basically at the notch before 210, maybe a liiiiitle bit to the left of the notch before 210. Just tried posting a link to the image of the temp gauge but it says I have to have 5 post or more..

Any other suggestions?
 

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2004 chevy trailblazer_ls
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Mines done this for quite some time. Very intermittent, and there are threads here and at the other site about it.
Once I replaced the SAIS valve (had a code) and the high idle didn't happen for about 6 months, then started doing it again.
Another time, about 18 months ago, the fuel pump lines over the tank rotted out, and I replaced the fuel pump and lines. Worked for about a year, then happened once more.
Iv'e had the scanner on it numerous times, no codes.
FWIW, it seems to happen more after being on the hi way with the cruise control an, then getting off and taking back roads.
Go figure.
 

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Discussion Starter · #5 ·
Mines done this for quite some time. Very intermittent, and there are threads here and at the other site about it.
Once I replaced the SAIS valve (had a code) and the high idle didn't happen for about 6 months, then started doing it again.
Another time, about 18 months ago, the fuel pump lines over the tank rotted out, and I replaced the fuel pump and lines. Worked for about a year, then happened once more.
Iv'e had the scanner on it numerous times, no codes.
FWIW, it seems to happen more after being on the hi way with the cruise control an, then getting off and taking back roads.
Go figure.
Yeah I have noticed it a lot too after driving on the highway and then getting off. Next time I stop it is doing the high idle.

I JUST put a new transmission in this (2 days ago) and want to get everything else sorted out.

Anybody else have any suggestions? I have searched and all I come up with is the thermostat, which mine was replaced. I don't just want to keep throwing parts at it in hopes that it fixes this problem.
 
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