Chevrolet Colorado & GMC Canyon Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
484 Posts
Discussion Starter #1 (Edited)
So I have no clue what is wrong with my truck. I have the 3.5L and When I want to pass someone on a 2 lane road or bypass and I floor it, it will down shift and hit the Rev limiter at 5k RPM and will not shift until I let out of the trottle. Also does it from a dig. Normal everyday driving it shifts fine but only does it when in high RPM. Took it to the dealer and they don't know what's wrong with it either. The only thing I have done transmission wise is install a low pro cross member. When I did I used my jack to support the tranny when I dropped factory x member. I didn't raise it up or let it drop. I've checked the transmission fluid and it seems fine. Has anyone else had this problem or know what I need to do to fix it? Thanks in advance!
 

·
Premium Member
Joined
·
5,710 Posts
Stock tire size, or tune to correct different size?

Just trying to determine if your tach is accurate and you're actually hitting the correct rev limiter RPM.

The tires would have to be too big though, and if anything you've make the tires smaller (that would make the tach display faster).

Transmission cant shift if you are floored. The rev limiter is doing it's job. I think the concern is finding out why you're at the limit.....

I may be wrong if the transmission is electronically programed to shift at the rev limit, but in the old day it was governed by fluid pressure and/or vacuum, and when you've got it floored the pressure/vacuum isn't going to allow it to shift yet. It will just stay at max RPM until you remove your foot from the floor. It seems as if your truck is indeed functioning that way.
 

·
Registered
Joined
·
1,061 Posts
Sounds like the air flow meter has got some junk in there making it give crazy info to the ecm causing it not to rev to the shift points.
 

·
Registered
Joined
·
484 Posts
Discussion Starter #5
Factory tire size, no tune. DIY intake and mbrp cat back. Normally, If you rev it in park or neutral it won't go over 4.5-5k RPM but if the truck is in gear and under load it will rev beyond that when you're at WOT. My truck won't rev beyond that limiter as it did before. So it could be a vacuum line, or something wrong with the MAF?
 

·
Premium Member
Joined
·
441 Posts
My trucks shifting was stupid. Fan clutch was locked up. I don't think the 4L60 is vacuum controlled.
Nope, tranny not vacuum controlled
 

·
Registered
Joined
·
1,061 Posts
A malfunctioning maf could limit or exceed what the Max rpm is set to. Looks like this truck is not reaching the minimums for a wot shift to happen. He may have it floored and the ecm is not seeing it.
 

·
Member's Technical crew
Joined
·
12,060 Posts
Go drive the truck, at least five minutes or so... Make the problem happen several times.. Pull back into drive way, with truck running but in park and wheels chocked, lay on your back and look at the CAT... Use a hammer to barely tap it, move up and down it while tapping. A SOLID clunk will prove to you that your CAT is clogged. If it sounds Tinny then the cat is likely ok, next thing to look at would be the MAF, Clean it and not with MAF cleaner, that craps a joke. Use Q-tips and Rubbing alcohol. Very carefully clean the black crap off the wires and then report back.
 

·
Registered
Joined
·
484 Posts
Discussion Starter #12
Tinny sound and cleaned MAF. Still same problem. I know I talked to you on Facebook bandit but just wanted to let others know the results. Not sure what to do.
 

·
Registered
Joined
·
484 Posts
Discussion Starter #14
No didn't throw any codes. The tech at the dealership had it hooked to a tool and made it do what I'm talking about and it still didn't throw codes. And they checked all the shift points and they were also in check.
 

·
Registered
Joined
·
1,104 Posts
the problem lies within your trans... i guarantee it. when my trans began going out it began with this issue...
 
1 - 16 of 16 Posts
Top