Sorry for posting in both the tuning forum and tranny forum but i am tryin to find out all the info i can. Ok, i had a tci 3000 stall in my car, replaced it with a SS4000 stall, started throwin PCM codes, 0756 0757 you know typical behavior for the new stall its not used too. pulled the pcm fuses and reset pcm and drove car around town, its used to the new converter now, yay, later on it started randomly unlocking and reverted back to the shift solenoid codes. i know theres nothin wrong with them cause when i clear the codes while driving it goes back to shifting properly, but thats not what im pissed about. i took it to get it retuned and asked him to tune the trans to adjust for the higher stall. he gave the car back and told me to drive it for a day to see how i liked it, no lock up at all for 2 days then it locks up from that point on, but in the mean time it takes a nose dive while shifting cause the TM was not zeroed out, i have a built trans with a shift kit so it can handle the abuse. so we go through the pcm again and turn off the TM and reset other parameters, i am not a tuner so i dont know entirely what was done. but i lost lock up or so i thought. it was locking but tap the gas and it just revs up to accelerate out of lock up. so we have been messin with this things tune for almost 3 weeks now and i finally made him put the lock stock factory tune on the car and it is still doin the same thing, slippin under lock up very bad, yank say the converter either locks or doesnt lock if its mechanically good or bad, there is no in between according to them. does anyone have ANY idea what the possible problems could be, i am tired of screamin down the highway at almost 3000rpm's, soon as i start coastin it goes to the rpm that it holds under lock up. and according to the hp tuners that the guy is usin, it is sending the apply/lock up signal. any ideas at all please?

 

Sounds like time for a new tuner.

 

The random locking/unlocking is common with big stalls and just takes a relatively easy fix to cure the problem. The tuner needs to raise the misfire threshold to the max value in all related misfire parameters (Misfire Mid/High RPM).

 

we have tried everything and every suggestion from the HP tuners forum and called many people on this. but still even with the stock tune loaded back onto it shouldn't it go back to locking and unlocking randomly? before i took it to him it would unlock at random very rarely.

 

The stock tune will make it worse. I had the same problem when I switched from a 3200 to 3800 stall and adjusting the misfire tables fixed it. It could be mechanical, but it really sounds like the tune. Have your tuner post the tables if possible.

 

i'll try to get him to do so but it locked up fine with the stock tune before, just had that random unlock very rarely on the interstate just cruisin. i hope its not mechanical but my luck it is.

 

You need to log TCC mode while driving and see what the PCM is commanding. I'm sure Gomer knows about the misfire tables. Your sig doesn't list a cam so I doubt it's misfires if the old converter locked OK. If the PCM is commanding lock and the converter isn't, then its mechanical. If it is commanding lock, one possibility is the O-ring on the input shaft was damaged installing the new converter, or you just got a bad converter. It happens.

 

what it is doing right now is when you are cruisin on the interstate at 70, it is doing upwards of 2500 to 2700 rpm's if you are coasting downhill at 70 it goes down to 2100 which is the rpm at lock up, if you tap the brake the rpms go down, release the brake rpms go back up to 2100, this is more noticable in 3rd gear cause the rpm difference when you tap and release the break is greater and easier to tell. but it is sending the command to lock up and it coast at the lock up rpm but as soon as you level out on a flat road to maintain 70 it cruises at the 2500 to 2700rpms. and this is on the factory tune that it was working just fine before. i dont see how it can just lock up normal and work fine except for the very rare random unlock and then just quit all together unless its something mechanical, incase you all havent noticed, i am very irritated right now lol. anyone know how to test for a mechanical problem? the pcm shows it is sending the command to lock up, and you can barely feel it when it does send the command but it doesnt drop more than 100 rpm's.

 

oh and for the Alabama people veiwing this it is NOT and i repeat NOT gomer that is tuning this car right now so dont be put off using him, he is by far the best tuner around this area on LS1's got me 35 extra horses in just 3 runs on the dyno.

 

Can someone explain why the computer would think a bolt on car would have missfires? A cammed car i completely understand, but a locking/unlocking condition on a car with just bolt on's and the stock cam seems unusual...I've tuned several large TC without issue including my own...I didn't have any lock/unlock issues UNTIL i added a cam.

 

I can't explain why some cars have the problem and some don't. But I believe it's the lighter weight of an aftermarket TC compared to stock which at minimal is usually a 10-lb difference. Less rotational mass right at the end of the crankshaft. Like I mentioned before I switched from a 3200 to a 3800 and mine started to act up. I wasn't on the stock cam, but the LS6 cam.