Pyschophrenic shifting 2002 LS1 Camaro

JungleJim · 01-23-2006, 04:30 AM

Anybody have experience with a tranny that can't decide to keep lock in torque converter locked at highway speeds? Normal operation tranny stays locked and 50-100 rpm changes makes car jump.
When in cruise control, car eventually can't decide which way is up, torque converter unlocks and tranny "slips almost 1000 rpm to make 2 mph change.
Is this a vacumn leak issue? Tranny is strong, under performance conditions stays locked to over 150 mph. Driving legally, can't decide what to do...and neither can I.

**toneloc60** · 01-23-2006, 04:48 AM

hmmm.... I don't know if the lock up on yours is controlled by vacuum or electronically. Can't remember... Damn alcohol in college...

You're telling me, that your lock up converter will actually stay locked up while at WOT? Are you sure? I mean, they're not supposed to. And I don't see you hitting 150 MPH pussy footing the gas pedal.

I'm kinda thinking you may need to replace your torque converter. How many miles on it?

JungleJim · 01-23-2006, 05:12 AM

The car has been driven by some heavy footed folks...it is a B4C police pursuit model. It has electronic 4 speed with OD. With all the torque it is hard to tell who is who when you get in it. Got a good shop working with me on the car, just had the tranny serviced, and entire car looked over. 93k on the car. As long as I keep torque on it, the tranny acts fine. It is when I am loafing that all the sillyness happens. It is a COMPUTER controlled tranny. twin solenoids for shifting, (just replaced) one handles the signal for 1st and 4th, the other 2nd and 3rd.
Drop it in neutral and back in drive, instantly locked. This is an intermittent deal, only begins after 40 plus miles. Fluid shows no sign of being hot.
Constant response from my mechanic buddy is that the computer is compensating for something...my feeling too...just what is the question

**toneloc60** · 01-23-2006, 05:28 AM

Try this, disconnect both of your battery cables. Touch the two cables together once they've been disconnected. Doing so will relieve the computers capacitors of their capacitive charge, and their memory. Reconnect the battery cables. Start your car and take it out on the road. Deliver the beating of a life time to your car for about 5-10 minutes. Doing this will remap the fuel curve. Then try to cruise it and see if you problem comes back.

One of two things is going to happen from doing this.

1. The problem gets better because your computer has hacked up its binary hairball.
2. The problem get worse because your computer will no longer have the long time memory of how to compensate and disguise the actual problem.

Either way, it puts you closer to getting back to enjoying your ride.

JungleJim · 01-23-2006, 05:55 AM

thanks for the tip. Gonna have to pick a "special" time for the beating. 10 minutes can eat up 30 miles really quick. (and wake up several neighborhoods)

Gonna do a thorough search for a vacumn leak first.

Kinda spooky thought to touch those cables together. Lotso electronic gismos that are gonna lose memory....As long as this ain't uncharted territory I'm game...thanks.

**toneloc60** · 01-23-2006, 07:12 AM

I've done it on many cars. Sometimes you have to just so the computer will quit hiding the cars issues.

Yeah, I was a little spooked the first time I did it, but, it works.

**hammertime** · 01-23-2006, 03:13 PM

Originally Posted by JungleJim

Kinda spooky thought to touch those cables together. Lotso electronic gismos that are gonna lose memory....As long as this ain't uncharted territory I'm game...thanks.

I would avoid touching the cables together by doing this instead.

Turn key on, don't start car
Pull PCM BATT and PCM IGN fuses in engine compartment
Wait 5-10 min
Turn ignition off
Replace fuses

**Capster78** · 01-23-2006, 05:23 PM

I had the same problems when I first bought myne. It was so bad that the car would just stall out while driving. Have you ever played with your shift points. this could be the problem. I had to purchase a Hypertech Programer and reprogram my shiftpoints and shift firmness to fix it.

The computer gets confused because the coverter is sliping alot more than the stock converter and doesent know what to do.

JungleJim · 01-24-2006, 05:51 AM

Well, it is all a moot point now. Lost 3rd and 4th gear clutches on way home yesterday. The doctor has the patient in surgery now. Thank God I have a fantastic tranny guy. Should be on the road with new tranny by Thursday. The doc knows me and the car, and is building tranny to suit both. Computer is programmed by GM to B4C specs. Gonna try fresh tranny before messing about with the best GM could do. They only built 587 of these cars in 2002. Its a good start, hoping that it was just the thrashing the car got on a daily basis that caused the entire deal. Thanks for the help, will reply when back on road to see if it was all mechanical abuse, or other issues.

**toneloc60** · 01-24-2006, 06:20 AM

I wonder if the programming that the B4C package got for the tranny was the same that SLP was doing. From what I heard that programming was terrible on the tranny.

When you get her back from the doc, buy a programmer and turn adjust the torque applied while shifting. By doing so, you end up with a shift that doesn't burn tires, but is a lot easier on the trans.

I heard SLP had these things tuned up to something like 50% and had 'em churpin tires even at lower RPM shifts. Terrible on the tranny.

TNT · 01-24-2006, 07:50 AM

Originally Posted by toneloc60

I heard SLP had these things tuned up to something like 50% and had 'em churpin tires even at lower RPM shifts. Terrible on the tranny.

It sure makes it fun to drive. Any suggestions what settings to use. I have my shift timing setting up and my shift pressure setting 50% or higher just for the fun of it but I wonder how much damage I'm doing over time. Any suggestions?

**toneloc60** · 01-24-2006, 09:46 AM

Originally Posted by TNT

It sure makes it fun to drive. Any suggestions what settings to use. I have my shift timing setting up and my shift pressure setting 50% or higher just for the fun of it but I wonder how much damage I'm doing over time. Any suggestions?

Actually, the lower the applied torque, the better. I was reading about it in another thread, but can't remember where.
The lower the percentile, the more the engine retards the timing during a shift. You will feel like this is making a significant difference in the performance of your car, but it will actually be a negligible difference in E.T. It will, however, make a substantial difference in the life expectancy of your tranny.

JungleJim · 01-30-2006, 05:26 AM

Back on the road. Doctor seems to have done a good job. However, will not know full impact of his work for a few days. His reabilitation program requires 500 miles of mild break in on tranny. For the patients health, he has depowered the brain. 325 miles...175 to go, hoping to get off probation for good behavior and tune this baby back to the ape that it really is.
Other little issues resolved. Hammered motor mounts replaced, finally got all belt pulleys, idlers etc replaced and tuned, no more belt noises. sooo...rebuilt rearend, rebuilt tranny...rear main seal not leaking but replaced at 93k. Almost have a car.....more soon.