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2005 chevy trailblazer_lt
4 Posts
Discussion Starter · #1 · (Edited)
I have a 2005 Trailblazer LT 4x4 with the 4.2 I6.
158k miles
Wife recently noticed (2-3 days ago) that the rpms have been fluctuating higher during shifting. I drove last night and confirmed.

35mph- 2500 starting rpms, shifts and goes up to 3000—3500 for a quick second and then settles back to 2000-2200

60mph- 3500 starting rpms, shifts and goes up to 4500 rpms for quick second and then settles back to 2000- 2200

Does not matter if light or heavy on gas pedal during acceleration. Same result.

I did clean the throttle body and reset the pcm (pulled fuses 10 and 28 for 15 min) last night and test drove after for about 15 min with same result just a little easier idle.

I'm not incredibly mechanically inclined but trying to learn a few basic things so I don't have to run to the mechanic every time.

From what I have been reading online I'm wondering if I have a pcm problem. Maybe transmission?

Only thing that is different is that I swapped out the secondary air pump with one from a junkyard about 2 weeks ago and when I did that I unplugged the positive terminal. (A BIG NO NO that I know now)

Any help is appreciated
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