Thread: New member - 2008 GXP Tranny problem - suggestions?

Hi everybody. I’m a long time GP owner. I’m on my 4th GP since 1993. I now have a 2008 GXP with 48,000 miles. I'm having this very inconsistent problem with the tranny. I had it into a dealer for a day and of course it never happened for them, so they say they can’t fix what they can’t find.

When the car is stopped and in Drive, I give it gas and there's a moment's hesitation as the engine revs up but the car doesn’t; move, then suddenly the tranny bangs into gear and the car takes off. Sometimes it’s a split second and a mild bang, sometimes it’s more like a full second and the bang is pretty bad.

There’s no rhyme or reason that I can tell. Sometimes it happens when the car is cold, and other times it’s hot. Sometimes it happens several times in a day, and then it may disappear for a month. It only happens when moving from a full stop. It never happens in reverse, and it never happens when the car upshifts to any other gear.

This has been going on for several months

The powertrain has a 5 year 100,000 mile warranty, and 5 years will be up in January. What I’m afraid of is that the tranny will finally fail after the warranty period is up.

Any helpful suggestions?

I have an 08 gxp as well. these are notorious for tranny failures. i've been lucky, i have 109000 miles on mine but i have lots of slipping. what has helped with chugging and hard shifts has been changing the fluid every 50k.

Originally Posted by GMCustomerService

kgf,

It may be transmission related. Are you receiving any warning lights?

Louis
GM Customer Service

Thanks for replying to everbody, even the guy who thinks I shoud blow the tranny up

Louis, No warning lights at all. Nothing in the DIC either. I am pretty sure it is in the tranny as the engine runs great and revs up when I press the gas.

The problem is intermittment and impossible to predict when it will occur.

About six months ago I took it to the dealer where I bought it. They had it for a day and drove it, but it didn't happen to them.

I just bought an '08 GXP- did a lot of research on it before I bought it. The main thing I found online was that the torque converters like to go out in these- a lot. Especially if you're running on the freeway for a long time. Makes sense, big motor lots of torque/heat. A couple people said to install a trans cooler, but a couple others said not to. I'm glad mine is under warranty because I'll probably smoke it by summer. Also, even though the DIC has a tranny fluid temp reading it's not real time like an analog gauge. GM specs said normal operating temp is 180-200 degrees for the trans, but the torque converter isn't built that tough and likes it a little cooler. Oh, and don't do a flush; everyone I've talked to about it says it's way better to drain the fluid if you're over 50k mi, 48K is pretty close. Weird question: does this ever happen when you're stopped on an incline? I ask because when I drive up all 12 levels of my parking garage my trans temp increases by about 8-10 degrees.

Originally Posted by SlowNA06

Going uphill very slow with very little air to cool anything? Yeah, that will heat up the trans.

Yeah, it made sense to me too. Here's the thing though, today stopped at a light with a slight incline- trans temp was about 145- at take off trans shifted into first pretty hard. Just something I'm noticing...

Originally Posted by marines542

More gxp owners!!! There's like a whopping >10 on here

Sent from my DROID RAZR using Tapatalk 2

Everyone is selling them for a decent price now that they're at least six yrs old- lots of problems!!! @ SlowNA06- at take off from full stop, slammed into forward motion hard- was not pulling enough rpm's to hit 2nd?- tranny fluid is looking good on the stick, but God only knows when the filter was changed last- Hopefully I can get to that this wknd? I've only had it 10 days. I still like BlueGuy's idea- genius,diabolical, but genius.

I have a 08 GXP with the very same prob. I could had wrote the very same info word for word,If you ever get any good info on our prob. would you pass it along ?