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Discussion Starter · #1 · (Edited)
The RPMs go way up 3500 - 4000 RPMs when you accelerate the car normally from stop (before shifting from 1st to 2nd). You can also hear that the engine is raving up. This only happens when going from 1st to 2nd gear...after that the RMPs are find and the engine sound normal. Also, there is no problem in the morning and this issue is intermittent. I had a check engine light on for about 1 month that said that the thermostat and the O2 sensor should be replaced (had no time to replace them). But now this new issue is bothering me. Do you know what this could be caused by? and could it be the thermostat and/or the 2 sensor? If i replace them would this issue go away? I have 120K on 2003 Envoy.

Thank you in advance and sorry in advance if this is a silly question.
 

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2004 gmc
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Ever service the transmission? Followed the recommendations in the Owner's Manual for maintenance items? I don't think the issues are related except as a consequence of deferred maintenance.
 

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:tiphat Welcome :tiphat .:iagree: .Also if you have a code for the t-stat, you are probably running cold and wasting gas.
 

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2003 chevy trailblazer_ls
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a failed thermostat- will cause the engine to run cold-- and use gas..
but- while it thinks the engine is cold- the computer also changes the shift pattern of the trans...
one thing it does is that the 1st gear change--- takes longer... and will revv a little more- then it goes into 2nd- kind of hard...
once warmed up- the 1st gear change is lower in the rpm range and smooth.
(thats how mine operates)
 

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2002 chevy trailblazer_ltz
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The RPMs go way up 3500 - 4000 RPMs when you accelerate the car normally from stop (before shifting from 1st to 2nd). You can also hear that the engine is raving up. This only happens when going from 1st to 2nd gear...after that the RMPs are find and the engine sound nor..........I have 120K on 2003 Envoy.

Thank you in advance and sorry in advance if this is a silly question.
Regardless of eng. temp, this sounds like excessive rpm for 1-2 shift....then again, what's your idea of accelerating "normally"? Some people really step into the gas harder than others.

I'd have those codes cleared out of the computer, and have the trans looked at by a good tranny shop.

BTW, please fill out your UserCP.....and welcome to the site.
 

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2003 chevy trailblazer_ls
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a failed thermostat- will cause the engine to run cold-- and use gas..
but- while it thinks the engine is cold- the computer also changes the shift pattern of the trans...
one thing it does is that the 1st gear change--- takes longer... and will revv a little more- then it goes into 2nd- kind of hard...
once warmed up- the 1st gear change is lower in the rpm range and smooth.
(thats how mine operates)
Psst: He said that it was fine in the morning. Tranny fluid might look like coffee.
 
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