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2005 chevy trailblazer_ls
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Discussion Starter · #1 ·
I just put in my tuned PCM, and WOW what a difference! In addition, I lifted and put bigger tires (265/75/16) on my 2005 TB I6.

Shifts are firm and quick on setting #2, power just seems to pour out of the motor when when you demand it whether starting from a dead stop or if you're going 65 down the freeway! I'm quite impressed with the change!

After installing the PCM, I have noticed that the speedometer is still 3-4 mph off at 70 mph (using a GPS unit to compare speedometer reading) and I haven't seen a check engine light indicating a CASE relearn is needed (I did the core exchange). I did specify in my order that I was running 265/75/16 tires.

Could it just be the error in the GPS that's giving different speeds? and if I don't see a check engine light, do I really need a CASE relearn? or should I go have one done anyway?
 

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i could see a 1mph difference between the speedo and the gps being okay, but gps is pretty accurate.

Id call them and have that checked out.

Also, i would do the relearn just in case.
 

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2002 non_gmt360 other
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I would trust the GPS. When I used my laptop GPS in various friends vehicles I would see up to a 5KM/H difference, which would only be about 1.6MPH.
 

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2005 chevy trailblazer_ls
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Discussion Starter · #5 ·
I tried to stop by the local chevy dealership but they had closed. I drive past it everyday on my way to school, I will just have to stop in on Monday or something.
 

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2003 gmc envoy_slt
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PCMforless turns off the CEL so it is not shining all the time. You need to do the C.A.S.E. relearn. You will not pass emissions test with the light turned off.
 

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2005 chevy trailblazer_ls
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Discussion Starter · #7 ·
I just thought of another question:

If i got my tuned PCM through the core exchange program, does the tuned PCM come with the latest GM calibrations or its it just left with whatever calibrations that were it in at the time it was taken from the donor vehicle then tuned?
 

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2003 gmc envoy_slt
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PCMforless does all the newest up-dates.
 

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2002 chevy trailblazer_ls
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I tried to stop by the local chevy dealership but they had closed. I drive past it everyday on my way to school, I will just have to stop in on Monday or something.
I had an automotive teacher hook me up at college on my case relearn free of charge. They had 11 tech 2 tuners there, just pulled it in, and a few seconds later I was all set.
 

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2002 chevy trailblazer_ls
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I tried to stop by the local chevy dealership but they had closed. I drive past it everyday on my way to school, I will just have to stop in on Monday or something.
I had an automotive teacher hook me up at college on mine free of charge. They had 11 tech 2 tuners there, just pulled it in and a few seconds later I was all set.
 

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2005 chevy trailblazer_ls
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343 Posts
Discussion Starter · #11 ·
Too bad I don't know anyone in the Auto Tech program at school! That would be nice.
 

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Discussion Starter · #13 ·
So i had the CASE relearn done yesterday. Luckily the GM tech didn't wipe out the tune in the process. I'm still having an issue with the speedometer though. Could the GM tech have re-calibrated that while it was in for the CASE relearn?
 
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