Hey guys.

An odd thing's been happening lately. If I go for a WOT in my 2.4, as in just all-out, pedal mashed, it takes off like it should. However, after I let off, it shifts really hard into the next gear and the CEL comes on. And everytime it shifts after that, it shifts very hard. It's like it has a shift kit or something like that it feels like. Nothing that would seem to really damage anything, I just want to make sure though. Then after I park it and turn it off, and wait a little, I come back out and it's fine. Good as new. Clearly it resets it's self. But why does it do it anyway? ECU issue of some kid I'm assuming. Something is throwing a gay signal of some kind. The only things I have done in my engine compartment, engine-wise is an Injen short ram, Mobil-1 syn oil, and a Mobil-1 oil cap. lol. I wouldn't figure it's from the intake because it never gave me a problem unti lthis and I've had it on for months. This has probably happened less than 10 times so far. Since it started, I have stopped going WOT. lol. WTF is the issue? If anything else, I'm going in to the dealership for my pre-going out of warranty check-up, so I'll see then...

Thanks!

 

i dont know much, but maybe your transmission mount is busted? so when you shift your engine hits real hard and sets something off. just a guess

 

I'd assume not since it resets its self after it's off. That's why I'm thinking it's an ECU issue. It wouldn't be the first ECU issue I had...

 

my guess that the cel you are getting is a po833 ....clutch pedal position switch ....mine does the same

 

^^^^ would that apply to an auto?

 

ok, first guys make sure your understanding this situation. this has nothing to do with any clutch switch.
being an automatic transmission, if you understand it, could be difficult to find the problem. but there are things to check first.

with every auto transmission there is a torque converter to buildup pressure to the oilpump, that then directs it to a valve body. the valve body then determines which clutchpack to engage,etc.

what could be happening is that some transmissions run on vacume or switch soliniods. what this controls is the downshift part of it. sometimes in some cases, these could get stuck. the valve body could be plugged etc. this is cuased of the clutch packs debree that mixes with the oil

THIS IS WHAT I RECOMMEND. and please read this carefully.
First i would recommend checking your fluid. smell it as well. if you smell burnt fluid or the red trani oil is brown. i recommend a TRANSMISSION FLUSH! and PAN SERVICE.
this service flushes the transmission oil. you want to flush through double the amount of the transmission capacity. (its a machine that usually connects to the trani cooler lines) this will make sure at least 80% of the fluid has been changed out.
with this service they could also onbolt the trani pan and take off the trani filter and replace it. after installing the new filter and cleaning the pan out. they will adjust the trani oil level.
MAKE SURE THAT IT IS JUST SLIGHTLY ABOVE THE COLD MARK. this fluid does expand and if it is to high, will create more pressure and bugger things up.

the auto trani that are put into these cobalts are not heavy duty. and need to be taken care of. proper maintanance is always required. if you are WOT the tranni, then the service interval shortens.

give this a shot, gm will not cover this under warrenty becuase they cant tell how hard your driving. although if the tranni no longer works. then they could replace it. and the only time they will replace it.

DO NOT USE ANY SYNTHETIC OR ADDITIVES IN THE TRANNI. my god people stick a lot of freakin garbage in there transmissions.
Its a hydrolic system. only use Regular recommended fluid regardless of what anyone tells you.

some shops will be like " we could put this additive in for your tranni to grab better" um..... these are comments made by people that dont have a freaking clue how a tranni works. additives could HARM your transmission and shorten the life even more. there is a reason why specific oil is used from the dealer. because thats what it was optimized for.

i just read someone say something about the ecu. although the ecu may have a small part about the operation. i doubt that that is the problem. i will try to show you what happens to a clutchpack that is engaging to hard and why a clutch could stick. under wot. clutches to get hot and if worn down "not saying yours is" could potentially weld themselves together. bassically seize.

http://www.cardomain.com/ride/2294560
this is of a transmission long ago i worked on wiht my pathfinder. you can see the burnt clutches, valve body with filter, and an opened up torque converter.



this is why proper maintanance is required

 

Get the ECM code scanned and fixed. Once that problem is solved your transmission problem may never come back.

A lot of DTCs will cause the transmission to default to full line pressure shifting as a safety default.

 

good point witt. dtc's are interesting with the bolts. i dont understand why it would go into full line pressure. but i could see it going into a safety mode