Torque converter slippage and harsh engagement

[NOSonTHErocks]

Iknow its like beating a dead horse with this subject but i like many people am having an issue with my torque converter
i ve had the fishbite chuggle issue for a bit and have replaced the pcm fixed for a few days here recently im getting harsh lockup engagement and and torque converter slippage under throttle according to scan tool can see slippage of around 500 rpm (BAD!!) shifts fine in to gears but not lockup gonna need a torque convertor soon seeing fluid getting dirty again is a dd so cant afford a lot of down time but i have tools available and i can do all work myself i am aware of the tsb with tps fix and no misfires present

vehicle is a 99 grand prix gtp with 155xxx miles tranny code mn7
flush and filter done month ago
have had p0741 one time in past no p1181 (pcs failure related i think)
have tcc solenoid and pcs solenoid on hand

im hoping to get some opinions on this subject i am a mechanic with limited experience and i have seen fixes for this in various forms from simple battery cable removal for computer reset to tranny replacement (obviously)
just trying to narrow problem down so i feel more comfortable with dropping the tranny for fixing

http://www.tripleedgeperformance.com/ has a lot of info on this subject but lists a lot of common could be failures

thanks for reading and thanks for any posts

[tblake]

Its not too difficult of a job job, but I feel that if you've got 155,000 miles, you might be better off installing a whole rebuilt tranny and not just a torque converter.

[NOSonTHErocks]

i was thinking about that but theres nothing wrong with the tranny itself no metal in pan shifts fine just seems that there could a problem with th tcc system somewhere

[BNaylor]

Do you have access to a GM Tech 2 scan tool or does yours have the ability to manipulate the TCC apply functions? Are your symptoms appearing in 4th - OD only?

[NOSonTHErocks]

genesis scan tool i can only apply on or off i think never really looked much with it

[NOSonTHErocks]

actually only in lockup in 3rd and 4th real harsh in 3rd lockup real fast too shifts to 3rd then almost immediately itll lockup the tc around 35 mph

[BNaylor]

Do you have a gauge available to test line pressure to see if it is in specs? It sounds like a pressure control issue but if you are sure the rest of the transaxle is mechanically sound then just go with the TCC-PWM and PCS solenoid replacement. Easier doing the partial engine/tranny drop and opening up the side cover versus swapping out the whole transaxle but you never know for sure and as Tim pointed out you have to consider your mileage. The slippage could be the clutch packs or some other internal issue. With a Tech 2 you can test shift timing to make sure it is not causing high line pressure.

[NOSonTHErocks]

man wish i had a tech 2 but man still pricey i know slippage is tc did some data logging only slip is in lock up i know the woven clutch is tough but how tough? i can get a tc pretty cheap (stock replacment) i thnk ill just replace the 2 solenoids for now and do a relearn see how it holds up pcs cause that big of problems huh?

[BNaylor]

I forgot welcome to AF.

PCS issue is a pretty common. I had the issue with my GTP. Also, it won't hurt reviewing this thread below at our Tips & Maintenance subforum. A little cleanup with Seafoam and an accumulator shift kit mod. Upgrade to Dexron VI. Good last ditch effort before deciding on a tranny replacement or the solenoids or you could do it in conjunction with the solenoids.

Click here

[NOSonTHErocks]

i did the dex vi conversion already but ill get some seafoam and kit from zzperformance (i read the subforum already) my eyes are starting to hurt from all the readng lol
o well if this doesnt fix it or help then ill get a tranny

AND THANK YOU FOR THE WELCOME

[NOSonTHErocks]

WELL got some good news!!! and some bad

replaced the solenoids and flushed it again with dex 6 fixed problems to a point!!! no longer have harsh engagement but still have tcc slippage but not near what it was rpm is 150 or less now but goes down at different throttle positions but it seems to be weird i can command it on with the scan tool and NO SLIPPAGE WHATSOEVER had this same problem at first and the new computer fixed it for a bit then all the other stuff started happening

i havent changed the tps i didnt figure it was causing a problem but have to check it out some more

any thoughts?

[BNaylor]

Sounds good to a point and good job! How does it feel in real world driving? Do you feel the slippage?

A bad TPS would cause a "fishbite or "chuggle" effect or erratic shifting. Just check it out with a multimeter (DMM) before replacing or wasting money. 5 volt PCM reference signal at the input and around .4 v at idle and 4.5 v at WOT at the output to the PCM. Linear and smooth reading from closed or idle to WOT. You can check it with ignition to ON.

[NOSonTHErocks]

while driving you can feel slippage but i got so used to pointing it out i can tell it from anywhere the fishbite is there its better than its ever been

i will check out the tps tomorrow at work.....ill look up the wiring diagram and go from there (gotta knock the dust off the fluke)

its just strange it doesnt do it when you control the tcc with the scan tool
so you think this is because without the scan tool its being controled by many inputs and with one of them bad causing the fishbite and when i control it it bypasses all the inputs and goes 100% duty cycle?

just trying to get a hang on operation therory

[NOSonTHErocks]

well i have to say the solenoids fixed it drove a good distanceo nthe highway and have to say just seem to get better and better even on hills hardly no slip an no fishbite!!!

[tblake]

Good deal! What solonoids did you replace specifically? (just for future reference)

Also I had some torque converter lockup indecision a while back. It happened slightly in 3rd and noticibly in 4th. The rpm would surge up and down for a split second right after lockup was commanded by the PCM. It was about a 150-200rpm surge. It started happening right after I put a ZZP stage 1 ported throttle body on. It did not have a MAF screen in it. Once I put the MAF screen back in, no more TCC lockup indecision, and no more idle surging. Its been a year now. (Just thought I'd throw that out there in case your issue sounds similar)