oaklandmr

If i'm driving along and then step on it from a stop, sometimes my car will kick off the t/c and then shift hard as hell. If that happens when I shift from drive to reverse, the car jerks. Now this only happens if I get on the car good from a stop or if I rev the motor while parked. When I shut the car off and let it sit for a min and start it again, its back to normal. Any ideas or should I take it to the dealer? Car info in sig. TIA.

BlwnGP

Tom,

My car is in the shop as we speak for the exact same problem. So far, they have cleaned the injectors (codes set were rich and misfires on #2), solution lasted for about 3 days and same problem came back. Now it is in there and they think it may be the MAF sensor. I will keep you posted on what they find.

They are trying to blame my GMPP intake. However, being a GM part they are going to have a hard time with that one. If it was the intake, it would be a lean code, not a rich code....

oaklandmr

Yea...i'm only runnin a drop in and have been for like 15000 miles and this problem just started about 2 weeks ago. Let me know and I guess i'll be headed to the dealer...i'm still under warrinty for awaile yet.

D4u2s0t

a couple things...

1) Don't rev the car hard while in park are you revving and dropping it into gear or something??
2) Make sure you're pretty much stopped before shifting your car from drive to reverse or the other way around.

BlwnGP

Um...if it was THAT easy, I don't think he'd be askin it! Tom is not a newb, and neither am I!

Mine started doing it while pulling away from a stoplight. It shifted so hard (1st to 2nd), I thought I got rearended....looked in rearview for the carnage....then looked down at the dash and saw the TC light on. I pulled over, shut the car off, restarted it, and it still was on. Went from park to drive and the car lurched forward again. I then decided to take it in. I started to head to the dealership and it shut off by itself - everything went back to normal again. But it did leave 2 codes in the system.

It has happened 2X over the last week, identical scenerios. It is currently sitting at the dealer...I just talked to them, and they can't figure it out yet. I am betting mine is something electrical or a short somewhere or a bad sensor somewhere....we'll see. They will have it for another day at least.

I was told by someone that when there is a drop in the system voltage, one of the first things the car will shut off is the traction control and go into limp home mode.

Again, I will keep you informed as I find out more.

BlwnGP

Well I got the car back last night. They still haven't been able to completely solve the issue. They replaced the pre-cat oxygen sensor and re-installed my stock airbox with a stock air filter. They want me to drive it and see if the code comes back with the stock airbox on the car. If all is good, they said I can re-install the GMPP intake and see if it sets the code again.

I am not too happy with the results, but, hey, what can you do? I am willing to try anything at this point.

Tom, any word on your situation? I tried to call your cell and the number was disconnected (I got it from McCann). I sent you an e-mail through Css.net and you haven't replied. Please reply so I can see if you have any more news.

BTW, the codes were:

C0561 in the EBCM
P0172 in the PCM

oaklandmr

No nothing has changed here. I havent had it happen in a couple days now so I'm not gonna worry about it till it happens again. I may take it to the dealer on Sat just to see if they can find anything...if not then whatever. Yea sorry I havent gotten back to ya...i wasent around a computer yesterday (class all day) and my cell # changed i just dont think I gave it to McCann yet (should prob do that). Let me know what happens.

And to D4u2s0t...yea i'm not doin those things so i know its not that...i know better than that. Thanks tho.

BlwnGP

Tom,

shoot me an e-mail with your phone number, I want to talk to you.

jason.bowden@skanskausa.com

I highly encourage you to take the car in. My dealership is hoping that you might be able to solve this problem at your dealership, since they couldn't. Chances are it will come back. Mine acted up for about 10 minutes, the light went off and everything went back to normal. However a week later it did the same thing (after I took it in the first time and they tried to fix it). If it happens 2X before clearing the code, it will actually set the SES light instead of the TC light. That is what my dealership is hoping my car will do now. They want me to keep driving it after it might set the code again in the hopes it sets the SES light the second time. Then they will have a hard code in the computer that will hopefully diagnose it properly.

BlwnGP

Well, so far so good. I am past the "magic" 3 day window that it took to set the code the past 2 times.

Maybe the problem was the O2 sensor? I find it hard to believe, but you never know.

I have decided to go ahead and replace the MAF (since I know it got damaged by the K&N oil and it is only $40), put a new set of plugs in the car (since it had a rich condition, misfires, and 3 injector cleans to foul them out), and a new fuel filter (in case I got a tank of bad gas since both problems occured on the same tank of gas).

We'll see if it returns after these slight fixes. I have a feeling that it won't come back after this small maintenance has been done, but I have been wrong before.

Good news is that plugs, MAF, and fuel filter are cheap and can be done in a short period of time.

oaklandmr

Yea I never got a chance to take it to the dealer. I've found that my problem with the t/c turning off and the hard shifts comes after sitting at like the bank or waiting at the fast food place and then taking off afterwards. I dont even have to be in the pedal much to kick it off. So i think that I have more problems than just a bad maf and such. I'm gonna try to get it in this weekend to the dealer. I'll keep ya posted.

BTW...sorry I ddint call you or write you back...ive been swamped with work and school.

D4u2s0t

no problem... just figured cover the basics first, ya know? i didn't know anything about your car knowledge, didn't mean anytyhing by it.

BlwnGP

Kinda unfair, since I know Tom prior to joining this board. I can vouch for him, he know how to drive sorta...

You may be surprised what the car will do if the MAF is not working properly or the O2 (I think it was my case).

The TC acting up and hard shifting is just a reaction...NOT a cause. You are experiencing the "limp home mode". I would be surprised if the solution has anything to do with your transmission!

These cars are even more electronically goverened than your old GP ever was. If you sneeze the wrong way your trunk release might trigger and the radio station might change stupid flux capacitor!

Keep me informed, I don't think my car is out of the woods yet...I will wait for the solution that your dealership finds out and we can compare notes.

oaklandmr

Sounds like a plan...i just re-oiled the k&n this weekend...ill have to look into getting a new maf and maybe i'll get a dry-flo filter and see what happens. I'd like to get the gmpp intake but dont have the $$ for it right now.

BlwnGP

Crate Engine Depot had them for $247 when I bought it. Funny, I ran into someone who had a G5 GT and just bought his. I asked him how much he paid....$330 with tax. OUCH! He was pissed when I told him $247 + $15 to ship.

Keep your eyes open if they have a sale...

They also have MAFs for like $40 and some change + shipping. That is where mine is coming from.

oaklandmr

Well I have an update...I took it to the dealer last night. I'm tired of it coming on all the time and whatnot...so I'm in a loner till they let me know whats going on. Its not all bad...i'm back in a w-body for awaile. I'll let ya know whats goin on when I know something.

BlwnGP

Post up when you get the car back. It sure would be ironic if they decide to just replace your pre-cat O2 sensor like they did to me...but maybe they will actually find the problem. I am taking the car back to the dealer this Saturday for the plugs, fuel filter, and the MAF install (I will probably do the MAF myself). I would like to let them know the results of your service too.

oaklandmr

Yea I havent heard anything yet...i'm gonna call them around 3 or so to see whats goin on.

oaklandmr

OK heres the scoop...the couldnt get my car to act up but they did have some findings. My MAF sensor was replaced due to it failing, and there was also a TCM and a PCM update for my car (both of which they say could have been causing my problem). I tried to get ti to act up yesterday and wasent able to so we will see if this has fixed it or not. Thats my finidings...sounds almost like the same thing your guys did.

BlwnGP

Sounds like good news. I talked to my service writer after reading this. We reflashed my PCM about 3000-4000 miles ago for a rough idle (probably caused by the K&N). Didn't really solve it, it still does it occassionly (feels like a slight misfire at idle). I will check to see if there are any more recent revisions. My new MAF should be here today or tomorrow, along with new plugs and fuel filter. I am planning on getting them installed Saturday. That should alleviate any more concerns. If all goes well (no codes anymore), I will be able to put my GMPP intake back on in about a week. I am keeping my fingers crossed, stock SUCKS *****!!! I definately noticed much better mid-range torque with the GMPP on the car.

Now get that K&N out of there, or else you might have this problem again! Go back to stock if you have too until you can afford the GMPP, it would be alot safer!

Thanks Tom for your help!

oaklandmr

no prob...yea i'm thinkin that I will put the stock back in until i can either get a GMPP or a dry-flo filter but I'm not even sure who makes a good dry-flo or if they make one for our cars yet or not. Its weird that this would happen on these cars and not on the prix's. My girl has a 01 GT and we havent had any problems with it and she is running the same k&n filter.

BlwnGP

I think the reason the Prix isn't like that is because the Cobalt (and all newer cars) have a heated MAF sensor. The heating element/combined with the more stringent sampling due to emisions make these newer ones more sensitive and not oil friendly. Yeah, I have even dropped the one in the Prix from about hood height (by accident) at least once and never have had a problem (not to mention running that SLP intake for over 80k miles-with a K&N 6" cone filter).

I guess they just don't make them like they used to!!!

I think AEM makes a dri-flow filter, but not sure how you could rig something up that would be effective. It is definately not like the Prix where a 3 1/2" diameter exhaust pipe, some Home Depot sewer couplers and an open cone and you are ready to go (MAF placement being in the throttle body itself)!

oaklandmr

I kinda wish someone made a dry-flo drop-in for these cars. Might be somethin worth buyin...i will give my car a couple more days to see what happens but doing what uised to casue the problem this morning, did not bring the problem back so hopefully its fixed. We shall see.

BlwnGP

Man, if you could only buy the GMPP in pieces (i.e. the tube (with the MAF sensor hole), the throttle body 90 elbow, a coupler, etc...), you could build your own for dirt cheap...oh well.

Halfcent

Sounds like a Throttle position sensor malfunction. If the TPS sends a signal of Wide Open, the Trans controller will make full pressure shifts.

BlwnGP

Thanks for the heads up! I'll have to check that out! That kinda makes sense considering that the second time my problem occurred, it was about 5-10 minutes after some spirited driving...hmmmm

Now the question is, wouldn't this happen more frequently than twice in 1 1/2weeks? or is it coincidence? (the first time it happened, I was sitting in stop & go traffic and had not been driving hard at all). However, would it have triggered a "limp home mode" condition and set off the TC off light (not the "low traction" message on the DIC)? My dealership told me that that was a reaction to the PO172 code set, not the cause...the plot thickens.