Long-Term Road Tests - 2007 Chevrolet Silverado LT: Things Going Whump In the Night

2007 Chevrolet Silverado LT: Things Going Whump In the Night

I've noticed over the last few days of driving the Silverado, the transmission has a peculiar habit. At the point where you'd think there would be a shift between first and second, the gear holds unusually long in first and then with a good "whump" it hard shifts into second.

It's a little disconcerting to say the least. We have an appointment on the horizon to see if there is anything wrong.

Scott Jacobs, Senior Photographer @ 21, 018

Posted by Scott Nov 6, 2007 10:53 am

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Categories: 2007 Chevrolet Silverado LT

Comments

member12 - May 3, 2008 6:27 pm (#6 Total: 6)

It sounds like a programing thing.

Take it out on an empty road and, from a stop, stand on the gas until it shifts through third gear. Turn around and repeat.

This should everything seated correctly and the transmission computer will adjust to your driving habits. You guys probably have a bunch of drivers with different styles....
It sounds crazy, but it worked on my friend's automatic Tacoma, and I've heard of the same thing on older 1990s GM 3/4 ton trucks.

Apparently flogging the hell out of it for a while helps it.

jdub53084 - Jan 2, 2008 10:45 pm (#5 Total: 6)

My 07 Silverado Classic(5.3/4L80 tras) which uses basically the same transmission doesn't seem to have the Whump noise. New cars will hold first or second to build up coolant temp to further lower start up emissions by trying to get the engine to operating temp as quickly as possible,which lights the catalytic convertors off faster.

redmaxx - Dec 20, 2007 11:22 pm (#4 Total: 6)

Phoenix, AZ

This is normal due to it being a truck. We had a 2003 Silverado and it did the same thing on cool or cold mornings. Hold the gear longer and then "whump" into second. It's due to the way the PCM orders the shift plus the slop in the drive line that has always been normal for Silverados.

bimmerjay - Nov 6, 2007 4:07 pm (#3 Total: 6)

I recall there have been multiple posts about this odd behavior with the Silverado... is it getting worse?

dph1 - Nov 6, 2007 1:30 pm (#2 Total: 6)

Most transmissions do hold gears a little longer on cold mornings to get the engine warmer quicker (I believe). My 06 Accord (as well as my 96 Accord) does this. However, shifting with a whump should not be a part of the equation I would not think. My car shifts just as smoothly (with no whump at all) between gears even though the tranny is holding the gear a little longer. Also, I thought there was already a post on this problem before. I guess it has resurfaced?? Was it checked out then?

hola_dan - Nov 6, 2007 12:38 pm (#1 Total: 6)

does this happen once the engine has warmed up??
back in the late 90's, my parents had a suburban and it did the same thing you described the silverado does.. i always asked my dad why this happened and he would tell me that it was because the engine was cold..
as soon as it warmed up, the weird behavior of the transmission would go away.
do you think GM is still using a similar transmission?