[SOLVED] Acceleration problem - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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  #1  
Old 07-28-2012, 12:53 AM
Bluestorm Bluestorm is offline
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2003 Chevy TrailBlazer LS
Black 4.2L I6 2WD
Join Date: Jul 2012
Location: US
Posts: 12
Acceleration problem

I have a 2003 Trailblazer. We replaced all the plugs, ignition coils, and removed the throttle body and completely cleaned both sides. The vehicle appeared to run smoothly until it warms up, about 30 minutes of driving. Now it accelerates on its own and is very hard to brake and stop. Once stopped the suv idles rough and seems like it is going to stall. The suv attempts to keep going causing hard braking until about 5mph when it stops the acceleration all at once making the suv brakes to lock up from all the pressure being applied to stop. Once moving forward again, the idle takes over and accelerates endlessly. I allowed it to go to see just how much it would accelerate and I started to apply the brakes once the suv broke 55mph. While coming to a stop I shifted to nuetral so I wouldnt be fighting against the engine and the RPM's shot up to 4k and were increasing until I placed it back in gear to prevent damage from the high RPM's. Does anyone have any idea what is going on?
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  #2  
Old 07-28-2012, 10:31 AM
Bluestorm Bluestorm is offline
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2003 Chevy TrailBlazer LS
Black 4.2L I6 2WD
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Not "Solved"

By the way this problem is not "solved". It would not let me post without a prefix and the only prefix it allowed me to place is "solved". Any help would be greatly appreciated...............thanks.
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  #3  
Old 07-28-2012, 01:09 PM
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Jason43080 Jason43080 is offline
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2008 Chevy TrailBlazer LS
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I am no expert nor claim to be one but it seems like it may be the computer making it run at such high RPMs. If you haven't already, I would strongly suggest unplugging the battery for AT LEAST 30 minutes and let the computer reset itself and then take it for a spin. Report back and let us know what it does the next time you drive it.
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  #4  
Old 07-28-2012, 03:01 PM
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petevw petevw is offline
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2002 Chevy TrailBlazer LTZ
Red Jewel Tintcoat 4.2L I6 4X4
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Quote:
Originally Posted by Jason43080 View Post
....it may be the computer making it run at such high RPMs. If you haven't already, I would strongly suggest unplugging the battery for AT LEAST 30 minutes and let the computer reset itself .....
Since you'll have the battery disconnected (and I recommend at least 35-40 minutes), you might as well remove the throttle body from the engine and give it a good cleaning, unless this has been done VERY recently.
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  #5  
Old 07-29-2012, 12:56 AM
Bluestorm Bluestorm is offline
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2003 Chevy TrailBlazer LS
Black 4.2L I6 2WD
Join Date: Jul 2012
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Posts: 12
Update

I removed both the positive and negative cables to the battery for 3 hours. I then hooked everything back up and started the vehicle and just let it idle for 20 minutes. About an hour later I took it for a drive first through residential streets(about 10 miles or so with many stops) then onto the highway. The suv seemed to drive as normal until exiting to turn around after 20 minutes of highway driving. When getting back onto the highway I could feel the vehicle surge back and forth and watched while the RPM's would drop from 1500 to 1000 back and forth. I stayed on the highway for an additional 15 miles and when I exited and came to a stop, the suv died. I restarted and found the vehicle losing power and stuttering. The vehicle died a second time when slowing to make a right hand turn. I didnt experience the high idle as before but the suv struggled to make it home. It did seem to run smoother when I killed the a/c but still studdered a lot the rest of the drive home. From a stop, it would almost die when I first stepped on the gas then would surge forward until the next stop when it would repeat. Any ideas?
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  #6  
Old 07-29-2012, 03:19 AM
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Jason43080 Jason43080 is offline
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2008 Chevy TrailBlazer LS
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Not the update I was hoping to hear. It maybe the fuel pump, hopefully someone on here with more knowledge can offer some more suggestions.
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  #7  
Old 07-30-2012, 03:57 PM
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Jason43080 Jason43080 is offline
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2008 Chevy TrailBlazer LS
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Location: Birmingham, AL
Posts: 40
Any updates, are you still having the same issues? It's a shot in the dark but you may want to try a bottle of Techron, Lucas or other fuel system cleaner. Some say they are a waste of money but I alternate between Techron and Lucas every few months. It may be something like clogged fuel injectors or something that a bottle of fuel system cleaner may fix or improve, worth a shot IMO.
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  #8  
Old 08-01-2012, 12:05 AM
Bluestorm Bluestorm is offline
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2003 Chevy TrailBlazer LS
Black 4.2L I6 2WD
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Nothing new

No new updates yet. I plan on cleaning the TB again and trying "Lucas" to see if I have any better results.
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  #9  
Old 08-01-2012, 12:41 AM
mcginner mcginner is offline
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2006 Chevy TrailBlazer LS EXT
Black Granite Metallic 4.2L I6 4X4
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Try a new gas pedal. These vehicles do not have a throttle cable. Take the throttle pedal off and inspect it for any damage. Also smell it for any burnt smells.
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  #10  
Old 08-19-2012, 12:10 AM
Bluestorm Bluestorm is offline
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2003 Chevy TrailBlazer LS
Black 4.2L I6 2WD
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Location: US
Posts: 12
Update

Finally I had a chance to reclean the tb. I disconnected the negative terminal during this process. After reassembling I took it out for a test drive. First thing I noticed was the A/C would only blow out the floor vents or the defrost vents. The vehicle performed flawlessly for the first 20 minutes other then the A/C not blowing out the dash vents. I drove it both residential then highway. After about 20 minutes and exiting the highway the vehicle started to surge and lose power. With the accelerator steady it would drive fine then lose power dropping 5 to 10 mph then drive normal again for a short distance until repeating the process. It never acted like it wanted to die and it never accelerated on its own..................Ideas from anyone? Could this be a bad accelerator pedal sensor or a PCM issue? Any and all ideas or suggestions from anyone would be helpful. By the way when I stepped on the gas, it would take off like the wind.
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