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2004 chevy trailblazer_lt
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Discussion Starter · #1 ·
Hey guys,

I posted a series of problems I've been having with my TB in the transmission area of the forum, but I wanted to see if opening one of the issues to the larger audience might prove results.

Basically my '04 TB loves to keep the speed its at. I do mostly city driving, so the most replicable issues are driving up to 30-35mph and when letting off the accelerator, the rpms drop from 2500 or something to 1000 and the speed barely changes. Ordinary driving makes it feel like giving it a little gas gets alot more power than it used to and letting off the accelerator does not make the engine stop moving. Heck, sometimes I can let go of the accelerator at 25 or 30mph and have the car keep that speed for well over a mile before having to stop.

It will do this at higher speeds, although not as consistently and the RPMs tend to be a little higher (like 1250 or 1500 instead of 1k).

Little things that I've noticed are:
1) trying to stop the car is difficult, as if the car is fighting you.
2) when stopping the rpms will go below 1000, pause, then below 800, pause, then down to 500. sometimes they will actually rev instead of pausing.
3) the car does like to drive on its own from a dead stop, but instead of going up to maybe 5mph it can go 10-12mph without having used the gas.

I had it into the shop last week, the jerk drove it 20 miles (!) and claimed that he felt nothing wrong, but still offered to update the codes and such since that MIGHT fix it. I took it back, had the manager ride with me, and finally he reluctantly admitted there was a problem. Regardless of it maintaining a 30mph speed without wavering for miles, letting go of the accel does not come with a corresponding feel of drop in power nor a remarkable deceleration. It's going back in to the shop tomorrow, but I wanted to see if anyone had any ideas.

Any ideas?
 

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2003 gmc envoy_slt
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7,190 Posts
It sounds like the Accelerator Pedal Position (APP) Sensor on the gas pedal is sticking. We have drive by wire. If the throttle body was sticking when you let off the gas, the engine would die.
 

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2002 gmc envoy_slt
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3,203 Posts
Possibly a dirty throttle body, resulting in the throttle plate not closing quickly or being partially held open. First thing I would do is clean the throttle body.

Next thing that comes to mind is a vacuum leak, which could cause a higher than desirable idle or engine rpms. If the leak was severe enough though, it should set the CEL and corresponding code. - Granted, it takes a pretty big leak with some systems to cause the CEL to illuminate and set a code. (My dad's Taurus practically had a wide open 1 inch hose before the CEL illuminated).
 

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2004 chevy trailblazer_lt
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Discussion Starter · #4 ·
Not the throttle body. That was supposedly cleaned when it was in the shop (regrettably.)

Also, the pedal doesnt feel like it is sticking. It feels like it is resetting properly, but the engine doesn't respond by dropping ALL acceleration. It drops some, but not all and sticks at around 1000rpms.
 

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2003 gmc envoy_slt
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Try pulling up the gas pedal with your foot next time it happens.
 

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2004 chevy trailblazer_lt
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Discussion Starter · #7 ·
Try pulling up the gas pedal with your foot next time it happens.
no luck. doesnt make a difference.

unfortunately i've found no reference to a car or suv or truck sticking at a speed. It's not just one speed, its 25, 30, 45, 60, just about any speed.
 

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2009 chevy
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That, my friend, is the way they work, the way it was designed.

I found this forum with the same complaint.

I took mine back to the dealer, they said that's the way it works, I didn't believe him, so he tossed me a couple of sets of keys. A new truck and a used truck, both worked just like mine, and just like yours.

These trucks use a "drive by wire" accelerator, if there was a problem, the PCM would throw a code.

I still don't like it, but you will get used to it.
 

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2004 chevy trailblazer_lt
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Discussion Starter · #9 ·
That, my friend, is the way they work, the way it was designed.

I found this forum with the same complaint.

I took mine back to the dealer, they said that's the way it works, I didn't believe him, so he tossed me a couple of sets of keys. A new truck and a used truck, both worked just like mine, and just like yours.

These trucks use a "drive by wire" accelerator, if there was a problem, the PCM would throw a code.

I still don't like it, but you will get used to it.
I've had my trailblazer for around 8 months. When I first got it, the suv seemed to like to "coast" more than the cars that I had previously driven. Got used to it, no worries.

Now, the car doesnt coast, it drives on its own. In normal vehicles, when you let go of the accelerator, you feel the engine lose power and the car coasts a little before decelerating. My Trailblazer does not lose power when you let go of the accelerator, it diminishes it, but it still remains. You still feel the car being propelled forward. This is fine at 5mph, maybe even acceptable at 10, but when the car drives by itself for MILES and maintains a speed and rpms as if it was in cruise control, that is NOT normal. An SUV is an incredibly heavy object and gravity/friction should slow a car at 30 or 65mph, but my trailblazer locks onto a speed and does not let it go. period.

Having my old man drive it, who has driven trucks for decades, finds it to be a problem and actually unnerving. I cant help but disagree with him when the car will jump back up to a speed after tapping the breaks a little.
 

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I've had my trailblazer for around 8 months. When I first got it, the suv seemed to like to "coast" more than the cars that I had previously driven. Got used to it, no worries.

Now, the car doesnt coast, it drives on its own. In normal vehicles, when you let go of the accelerator, you feel the engine lose power and the car coasts a little before decelerating. My Trailblazer does not lose power when you let go of the accelerator, it diminishes it, but it still remains. You still feel the car being propelled forward. This is fine at 5mph, maybe even acceptable at 10, but when the car drives by itself for MILES and maintains a speed and rpms as if it was in cruise control, that is NOT normal. An SUV is an incredibly heavy object and gravity/friction should slow a car at 30 or 65mph, but my trailblazer locks onto a speed and does not let it go. period.

Having my old man drive it, who has driven trucks for decades, finds it to be a problem and actually unnerving. I cant help but disagree with him when the car will jump back up to a speed after tapping the breaks a little.
OK, speed increasing is definitely a problem. I would pull the throttle body and clean it. This is the only mechanical area and you might have a little sticking in the butterfly.
 
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