Performance Tune/torque management/damage to drive train
 

I have a performance tune in my car. I am assuming that the tune does away with the torque management portion of engine management, since throttle response is so incredibly improved after loading the tune.

I went to the strip for the first time the other night, and when I went to do my tire cleaning burn out, I rev'ed to about 4500, and released the clutch. What ensued was peculiar to say the least- the car lurched for a moment, then the whole body torqued, and the tire chirped for an instant, then it practically killed the engine.

I had mistakenly left the TCS on, because I had to turn the car off while I was in line at the track.:banghead:

Now I have a strange rattle on hard acceleration, that sounds like either an engine mount or a trans mount might be torn up, or maybe even a driveshaft problem. I haven't crawled under the car yet. I now have a lot of clunking when I accelerate and then lift the accelerator.

My question:

If you have a tune that removes torque management, and you leave the TCS on and drop the clutch, wouldn't that be just like putting your wheels in a vice and dropping the clutch? This can't be good, right? The TCS throws on the brakes, and the engine is screaming away, developing max torque. Something's GOT to give- no?

Thanks for any replies- sure would like to hear from the racers out there.

Does the rattling sound more like pinging or knocking from the engine? I have had occasions where pinging occurs under hard acceleration. From what I hear this is not uncommon when retuning the computer.

No. This is not a spark knock. It is a chassis/driveshaft/drivetrain knock.

Are you sure about that? I was under the impression is simply closed the throttle.

No, It brakes as well...

Yeah, that is probably not good, although the damage (whatever it may be) is probably not from the TC engaging the brakes, but rather the 4500 drop you did. Especially BAD on a dragstrip with all the rubber and VHT near the starting line and burnout area. Those tires just grabbed HARD and like you said it's like having them in a vice, something has to give. The TC only engages once the wheels are spinning, and if you are going straight, it will let them spin quite a bit for best traction. It gets really aggressive when spinning in a corner.

Anyway, any damage is probably to the U-joints, or rear end gears. possibly the clutch packs in the diff. You can check for play in the drivetrain by jacking the rear end off the ground with the e-brake on and in 1st gear. crawl under and rotate driveshaft by hand and see how much play you can feel. It should not rotate more than 1/16 to 1/8 turn. more than that and you've got a problem.

Thanks for the info- I'll have to jack the car up and check out the rear end and driveshaft.