Rough shifting, I'm Stumped [Archive] - GrandAmGT.com Forum

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Hanauer51
08-26-2013, 01:55 PM
Hey all, been awhile since I've been on here since summer is a crazy for me, but I'm having some major problems that I can't figure out what so ever.
I just put a new tranny filter kit in, and drained and refilled the fluid.
Changed both front bearings

Heres the problem, when I shift from Park to Drive the Car jolts and makes a clunking noise, then when the car shifts from 1st to 2nd gear I can feel it shifting pretty rough. I have no codes for any tranny problems, so I don't think its the transmission. I do have a couple of codes that I can't recall at the moment, but I know they start with a "U" and one of the codes is a bad connection between the PCM and BCM. So, can a bad PCM be linked to the rough shifting? I'll spark the car up, and sometimes it'll drive perfect for 10 miles, then all of a sudden the SES, SVS, ABS, and TRAC off all comes on at once, and then it proceeds to shift rough. Any ideas????

sleepyalero
08-26-2013, 02:36 PM
Usually all those lights mean wheel bearing, a bad connection with the iat can cause harsh shifting.

Hanauer51
08-26-2013, 02:48 PM
I know for sure its not a wheel bearing, I also thought it was the iat sensor, so I ordered that and we can go from there. Thanks buddy :)

sleepyalero
08-26-2013, 03:06 PM
No problem my friend, hope that solves the issue. Where did you order the IAT?

TDavis
08-26-2013, 03:16 PM
Bad torque converter?

sleepyalero
08-26-2013, 03:25 PM
When i thought bad TC on my stock trans my car wouldnt stay in O/D.

I would drive on highway doing say... 70, held 2000 rpm for about 5 seconds then pop out of OD and go up to about. 2300, i was getting horrible mileage.

destroyer179
08-26-2013, 04:03 PM
Check your motor mounts as well. I thought my trans was going out last summer but my mount was bad so when it shifted the engine would jump and make a clunk. That wouldn't cause lights but it could be more than one issue.

sleepyalero
08-26-2013, 04:13 PM
Also agree with above! ^

sugar ray
08-26-2013, 07:10 PM
My 3400 did this once. It was a bad tps. Throttle position sensor. Check that out!!

PhantomLover007
08-27-2013, 07:55 AM
Mine did the same thing.. TPS

Especially if the RPM's are up

Hanauer51
08-27-2013, 07:09 PM
thanks for all the feedback gentleman, I replaced the IAT sensor and threw a new pig tail on there.. So far so good, I've driven a good 20 miles on it and it shifted really smooth. As for the ABS, SVS, and TRAC lights they are still on. I'd go in and clear the codes and the lights would disappear, I'd pop it the car into Neutral and just turn the steering wheel in each direction and all the lights would pop back on. I know for sure it's not the bearings, because I just put two new fresh Timeken bearings on. So, now I'm going to have to investigate everything underneath going from harness to harness. I keep getting a code for the RF (passenger) side, so I'll start there. Thanks guys :)

rjs_boy
08-27-2013, 08:21 PM
Definitely check that the speed sensor wires didn't get pinched or damaged. ABS/SVS/TRAC trio usually indicates something wrong with one of the speed sensors. When I replaced the two front hubs, I forgot to hook up one of the sensor cables and was quickly greeted by all three lights. Clicked it in and lights went away, ran great until I drove through a good bit of water. Took the connectors back apart, blew them out with shop air and put some dielectric grease on them and have not had any problems since.

If it happens when you turn the steering wheel, it really sounds like a bad wire or connection since they would move some as the wheels turn.