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2002 chevy trailblazer_ls
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28 Posts
Discussion Starter #1
I've done a lot of searching on the forum and am aware of the "900 idle club" lol and have a list of possibles to check, but I think my issue may be more serious.

2002 TB with 293,00 miles. I noticed in the past two months an intermittent high idle, but rare and honestly I didn't pursue it.

Today though it was idling at highway speeds. Foot off the gas idling at 60 mph rpm at 2000-2200. Stopping at red lights (scary lol) having to hard hold brake. Part way home started acting normal, rpms dropped , speed dropped as should then after about 5 min started up again.

When I pulled into my neighborhood I stopped, then took foot off brake foot off gas and let idle in gear. It accelerated to over 30 mph and was still climbing and shifted gears before I braked. Rpm in the 2000-2500 range. Stopped and put in neutral. Rpms shot up to 4500. Turned it off and back on. It drove normally again for the brief drive back to driveway.

Any thoughts would be greatly appreciated!
 

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2002 chevy trailblazer_ls
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28 Posts
Discussion Starter #2
Since I posted I have replaced upstream O2 sensor (was time one way or other) cleaned throttle body per procedure and checked for vacuum leaks. The cam position sensor was replaced last year but noticed wiring looked questionable so replaced that.

Thought problem solved, drove great for half hour today then problem came back at a red light. 1200 rpm at light, put in neutral went up to 2500, put in park up to 3500 rpm. Parked and turned off. 15 min later cranked up and idled just fine. By the time I got home though was back to high rpm.

Any ideas of a direction to look in?
 

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2004 gmc envoy_sle
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2 Posts
I think I have the same thing

My Envoy is having an issue with the RPM revving high when I shift into gear. Gotta make sure the brakes are on hard or the vehicle will move. Take it out of gear and it initially revs high and then settles to 600. Put it back in gear, same issue. I am aware the engine control will compensate for the added load when put in gear. It now just does it way more than it used to and more than needed. I have cleaned the throttle body. Replaced the IAT, MAP, any vacuum hoses. I've searched for threads with the same issue, but I seem to have the opposite of what others are having with theirs dying when put in gear. I'm at a loss. No codes. My next thought is the fuel pressure regulator. Any thoughts? Thanks.
 

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2005 chevy trailblazer_ls
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49 Posts
Has anyone suggested looking into the accelerator pedal switch? Or the servo motor that turns the throttle butterfly? To me it sounds like the throttle butterfly is opening and staying open when it shouldn't.
 

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2008 gmc envoy_slt
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3 Posts
same problem high rpm

hello i have a high rpm problem with my 08 slt i6 envoy. my battery died about two weeks ago (got pretty cold here in nj battery was getting weak so i replaced)now have rpm issue i have cleaned tb with cleaner(removed) tried several "relearn" procedures . when started its around 1200 then settles at 600 and will sit there and purr at 600. when I put reverse not touching any pedal about 15ft of backing up jumps to 1200. when going from stop release brake and truck will go my itself till about 30mph. really have to stay on brakes at stop signs until it drops(about 20 sec)only code is p0449 which has been on since i bought truck used 3yrs ago.
 

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2008 isuzu ascender
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975 Posts
Try resetting again. pull fuses 10 and 28 and leave out for an hour or so and then put back in .
 

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2008 gmc envoy_slt
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3 Posts
i pulled those two but only for about half hour will try for hour now. I noticed on my scan tool the IAT is 71 degrees (its 38 here today) is that normal? I thought I read 10 degrees one way or the other
 

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I've done a lot of searching on the forum and am aware of the "900 idle club" lol and have a list of possibles to check, but I think my issue may be more serious.

2002 TB with 293,00 miles. I noticed in the past two months an intermittent high idle, but rare and honestly I didn't pursue it.

Today though it was idling at highway speeds. Foot off the gas idling at 60 mph rpm at 2000-2200. Stopping at red lights (scary lol) having to hard hold brake. Part way home started acting normal, rpms dropped , speed dropped as should then after about 5 min started up again.

When I pulled into my neighborhood I stopped, then took foot off brake foot off gas and let idle in gear. It accelerated to over 30 mph and was still climbing and shifted gears before I braked. Rpm in the 2000-2500 range. Stopped and put in neutral. Rpms shot up to 4500. Turned it off and back on. It drove normally again for the brief drive back to driveway.

Any thoughts would be greatly appreciated!

Did you ever figure out what this problem was? I know this is an old thread but my 08 Trailblazer just started doing the exact same thing. Cant figure it out it's really frustrating
 
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