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2004 chevy trailblazer_lt_ext
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119 Posts
Discussion Starter · #1 ·
04 TB with I6, RPMs drop about 100 RPM from time to time (fairly frequently). Battery and charging system check OK at autozone, new plugs (AC Delco), cleaned throttle body and I use injector cleaner regularly.

Got 80K miles, no major mods.

K&N filter recently cleaned and charged.

What could make the RPMs drop?

OH, no trouble codes thrown. I'm almost leaning to an old O2 sensor.

Your thoughts??
 

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2004 gmc envoy_slt
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221 Posts
Mine does this as well, but more then 100rpm at time after a trip somewhere it can say I am doing 1000rpm but driving 110k/hour... then when I shut off the truck when I get home it stays well below 0rpm and when I go back out later in the day or next day, it's fine for who knows how long.
 

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2004 gmc
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26,181 Posts
... it stays well below 0rpm ...
You sound like you don't have a real RPM issue, but just the gauge is reading in error. You have the stepper motor problem - there's a How-to article. Search for it.

...cleaned throttle body and I use injector cleaner regularly....
Your issue used to be a big mystery until a few members posted their solution was to clean gunked up screens on the Cam Position Actuator. Some folks were getting it fixed by an oil flush - others remove them (after getting the PS pump out of the way first) and clean them manually. It seems that is going to be a popular PM from here on out.

I may have this problem myself, and I have a squeaky clean throttle body and injectors with 80K miles as well, and I'll take some pics if I clean it.

Good description just posted recently:
http://forums.trailvoy.com/showthread.php?t=60954
 

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2004 chevy trailblazer_lt_ext
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119 Posts
Discussion Starter · #4 ·
Solved

Well, I picked up my TB from the dealership today. They only had it for 5 weeks.

Symptoms were in the below threads, basiclly, poor throtle response and erratic RMPs to the point the TB would stall.

PROBLEM FIXED: part of the issue with performance was a clogged catlytic converter. The erratic idle was from a perfectly good oxygen sensor (up stream one). I had replaced the OEM original one with a Bosch. The Bosch passed every test and did not throw a trouble code...but it was the culprit of my problem.

O2 sensor was replaced with an OEM one and my TB is running like NEW!!

Free from the dealer as they chased the same gremlins:

new throttle body
new engine head
new fan clutch
new catlytic converter
new vaccum lines
new O2 sensor

I basically have a new motor (minus the block)!!


http://forums.trailvoy.com/showthread.php?t=76751
http://forums.trailvoy.com/showthread.php?t=73821
 
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