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Discussion Starter · #1 ·
Hello, I'm new to trailvoy and there seems to be a wealth of knowledge to be found in these threads so here goes....

My 2002 Trailblazer LTZ (4.2 I6) has been running at high RPMs, around 6,000 at 65mph + and it doesn't seem to shift. Initially it would bog down when I first hit the pedal then after it started gaining speed it would rev high and stay there with little power output.

One shop thought it was a fan clutch issue which was replaced 3 years ago but decided that wasn't the problem, then they thought it was an AC issue because the problem is exagerated with the AC on high, then they thought it was a transmission problem but a local transmission shop said it was fine that it was a fuel filter.... Help!!

I replaced the fuel filter and it runs better in the lower RPM ranges but still revs high at higher speeds.

Any thoughts? Thanks for your help.
 

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2009 chevy
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6,431 Posts
Are you saying, that you've had this problem for 3 years OMG

You need to be able to tell what gear you are in at 65 mph. Can you feel the transmission shifting?

Can you see the transmission shifting? Watch the tach. With each shift, the rpms should drop and then proceed to climb again.

At 65 mph, in 4th gear, the tach should be around 2000 rpm.

Let us know
 

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2004 gmc envoy_sle
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What???

You have got to be joking....6,000 RPM at 65 MPH???? Man, something is seriously wrong here...It evidently is NOT shifting out of 2nd gear to rev that much....you are going to be very lucky if you haven't done some heavy damage to the engine if you've driven it much like this. I am surprised it hasn't completely fallen down and given up....the PCM is supposed to keep the engine from "over revving" but appartently it is not designed to keep this from happening.
You could have issues with the shifter, PCM, several sensors involved here or the electronic Tranny itself. I would not drive it over 30 MPH in this case and not for very long time either.....Good Luck you are gonna need it!:weird:
 

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2003 gmc envoy_slt
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If we're not being trolled here, then you really need to find a decent mechanic. You do know that putting the shifter in "2" makes it stay there and not shift, right?
 

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2003 chevy trailblazer_ls
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are you sure youre doing 6000?
Can you hear the engine revving that high?

or is the stepper motor on the dash- acting up?
 

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2002 chevy trailblazer_lt
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68 Posts
similar issues

I just had a similar problem today on my way to work... Inital start was very sluggish and a huge lack of power could put the pedal to the floor and would only go about 10ish MPH when coming out of a street into traffic! While my RPM didnt hit 6k it was doing 3-3.5k at 65-70 respectively. I also noticed that my cruise control wouldn't work and that even if I tried to shift it "manually" that when in 1st it would still be in second and then i would shift to OD and it would stay in 3rd. I have a code but do not have a scan tool nor have I made it to a parts store to have it checked and cleared, but after i picked up some lunch and it sat a little while it started working again like normal. Not sure if it will help diagnose either of our problems but seeing as we have similar vehicles (same year and similar trim, mines an LT) it might be closely related. Hope we can solve this issue
 

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Discussion Starter · #9 ·
Thanks everyone for the ideas. Your not being "trolled"??? I have 95,700 miles on the Trailblazer and it hasn't been happening for 3 years, that is when the fan clutch was replaced. I do realize that if you put it in 2nd it will stay there......... I typically have it in drive and it is only happening if you are at around 60mph and hit the accelerator to pass or need to get up to speed quickly. In that case the RPMs will jump up to around 5000 or sometimes 6000 (not kidding here) and stay there. I hear the engine and it sounds like it is running at this high of RPMs so I don't think the tach is giving a false reading. Im not flooring the pedal either.

I've been to three different shops and have been told that it is either a fan clutch, an AC issue, or that it needs a transmission rebuild. The second place said transmission but the shop they suggested to do the work said it was a fuel filter. I replaced the filter but the problem is still there. It runs a little better but not like it used to. All three places confirmed the issue so I'm not crazy. At least I hope not.

Thanks again for any ideas you might have.
 

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2003 gmc envoy_slt
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Thanks everyone for the ideas. Your not being "trolled"??? I have 95,700 miles on the Trailblazer and it hasn't been happening for 3 years, that is when the fan clutch was replaced. I do realize that if you put it in 2nd it will stay there......... I typically have it in drive and it is only happening if you are at around 60mph and hit the accelerator to pass or need to get up to speed quickly. In that case the RPMs will jump up to around 5000 or sometimes 6000 (not kidding here) and stay there. I hear the engine and it sounds like it is running at this high of RPMs so I don't think the tach is giving a false reading. Im not flooring the pedal either.

I've been to three different shops and have been told that it is either a fan clutch, an AC issue, or that it needs a transmission rebuild. The second place said transmission but the shop they suggested to do the work said it was a fuel filter. I replaced the filter but the problem is still there. It runs a little better but not like it used to. All three places confirmed the issue so I'm not crazy. At least I hope not.

Thanks again for any ideas you might have.
So the trans down shifts and won't up shift again? That is very plausible. When was the fluid last changed. Was it ever changed? Don't know if it will help but it is just about time for a fluid and filter change anyway if it hasn't been done before.:m2: Sorry about the trolled remark. But you made it sound like it never shifted out of second and you drove it that way for three years.
 

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Discussion Starter · #11 ·
Thanks WOOLUF1952. That is correct it will down shift and stay there for a while with the engine screaming. When it does finally shift it isn't as smooth as normal, kind of a hard shift. If I slowly get up to speed I don't have this problem. Never thought about explaining it that way... :duh:

To answer your question. I have never changed the fluid but can't say for sure if it was changed when I bought it at 38,000 miles (probably not). None the less you are correct in saying that it needs changed now because when I looked at it tonight it is kind of brown but should be more of a pink or red color, right?

No problem on the "trolled" remark...to be honest I don't even know what that means.... On the surface I guess my original claim did sound a little odd.
 

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2003 gmc envoy_slt
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Yup, it should be red. Go to the Dexron VI when you change it. I'm not sure how the term (trolled) came about, but occasionally someone will sign-up with a new name and give a really outrageous scenario about a problem. But, I stand by my original statement about needing a new mechanic. One of the places you went to should have questioned the dirty trans fluid.
 

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Discussion Starter · #13 ·
Solved, I think

Just wanted to update the post now that the issue has been resolved. It ended up being a clogged catalytic converter and now that it has been replaced it is running much better than before. It just happens that the day I took it to the shop the check engine light showed up and it was for that issue. Why it waited this long to come on is frustrating but at least it is fixed.
 
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