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2002 chevy trailblazer_ls
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5 Posts
Discussion Starter · #1 ·
Hi,
I just bought a 02 trailblazer LS.
I found a small problem: sometimes (maybe 1 in 5) when I start the engine, the RPM is high (11000 RPM while normal is 600). And I can hear obvious noise from the hood especially if I want to accelerate. It will disappear after a while, or if I stop it and stop it again, it will be fine.
Someone on the forum said it is due to cold, but here is not cold now around 80 degree. And someone else said it is due to the fan clutch.
Can anyone give me more information?

thanks a lot,
 

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2002 gmc envoy_sle
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1,380 Posts
Unfortunately I can't say since I haven't had to replace mine yet but there are alot of people on here that have. Hopefully one of them will weigh in with their input.
 

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2,819 Posts
You'll always have a high RPM at start up even when it's cold or hot i live in vegas today was 100* plus and mine did it if you start hearing clicking under your hood then you'd have to worry bout the clutch
 

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2003 gmc envoy_slt
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270 Posts
From my experience, when the weather begins to get hot, even after sitting in a parking lot all day, my fan engages fairly heavily for the first few blocks. I have not heard the telltale "clicking" that other clutch failures have made...

But I agree, when the engine is "cold" just after start, the RPMs should be a bit high and slow down as it warms up.
 

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2004 gmc
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26,181 Posts
The programming in the PCM includes a table of desired idle RPM versus coolant temperature. It might be slightly different for your year, but here's mine (observed with EFILive tuning software):



The noise is the fan clutch, and sometimes (not always) when you park it, the silicone fluid drains differently. It's not a problem unless the noise extends more than a couple of minutes after you drive off.

Search for a thread called "Fan Clutch 101" for more details.
 
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