I am intrested in a solution to this problem as well.

I recently purchased a scan tool. Actron cp9145. No codes, and not other problems according to the computer.

Has the ECM flash been done yet?

i guess the ecm flash had already been done to my car when i bought it two years ago. the dealership i took it to last week said there'* nothing to update. this makes sense because i got the car used from the gm dealer that had sold it to the original owner, so they probably did the updates when it was traded back to them. so, if this is true, the ecm flash will not help the surging issue. my surging has developed while i've owned the car. my next plan of action is to have the TCC slip looked at and TCC control recalibrated in the PCM if it is slipping too much. we've been guessing all along that the flash wouldn't fix the surging, so i guess here'* the answer. i've been hesitant to pay someone to put my car on the scanner to check TCC because i'm looking into getting a scantool around Christmas and could check it myself? if you get this done, please keep us posted!

Any updates to this? I think my cars tranny is starting to 'chuggle' when going up hills in OverDrive on the highway. Its not bad, and the RPM gauge isn't fluctuating, but I'd like to see what the end result of this thread is.

I'm up to 127k now, so I guess 130k isn't bad for a tranny.

how much does it cost to have your PCM reflashed? A dealer hasn't touched my car since it was brand new and maybe this could fix some of the problems I have been having?

the pontiac dealer here in ames quoted me approx. $75. this seems consistent with the numbers another member was quoted. if you can find an independent garage to do it you'll most certainly spend less than that. the garage i called told me it was a "dealer-only" procedure, which is illegal according to DrJay, but they denied that they could get access to the GM database. so i guess maybe ask around a little? let us know what you find out.

I would have bet big that my surging problem was the tranny or TCC. But I saw some earlier posts early this year that suggested ignition. I replaced plugs with Delco platinums, and went to MSD coils and wires..No more surging...Car runs better than new now at 119K...

This thread sounds like there are lot of confused members as to what TCC lockup does.

A lot of advice out there suggesting Shot-gunning parts with out the proper tools to diagnose the actual problem. Unless you have deep pockets and don't mind throwing money out in hopes of correcting the actual problem then you should invest in a scan tool or take it to someone to scan. The scan tool may not prove out your problem but may eliminate some unknowns and probably save you a lot of wasted money.

TCC lockup is the mode which locks the Torque Convertor so that there is a 1:1 ratio ( the engine is in effect is directly coupled to the transmission input shaft.) Thus this how there is a saving on fuel and no slippage is occuring. So it is only locked in cruising mode with limited torgue on driveline. If you step on the brake it disengages the TCC lockup feature and the torque convertor is permitted to slip. If the computer senses slippage and/or tranny temperature high it will shut down the TCC lockup feature. Also, if the TCC was to stay locked as when a solenoid fails then when you stopped at a light your engine would stall.

It appears some members have a rough running engine ( probably a sensor problem) which shows up as a vibration or chugging while driving.
While others probably have a transmission problem with OD and TCC lockup being shut off causing an RPM increase and possibly a rumble noise.

My 95 has a recent transmission rebuild, the original tranny lasted 201k never serviced. Shortly after rebuild , approximately 15k miles, started losing OD after 45 minutes normal driving or sooner if heavy on the pedal -noticeable by a 500 rpm increase and a rumble noise at about 65-70 mph.

I have had my scan tool hooked up while driving. The transmission does show a code while no engine light present regarding TCC malfunction. What I have observed is that it happens when the temperature reaches approximately 185 degrees ( temperature which tranny fluid degrades rapidly).

I was losing antifreeze which I was topping off every so often - this is a serious problem even if you aren't running hot on the temperature guage on SSE & SSEi. If you open the radiator cap look in you will observe a stacked of round disks. Your car motor could be cool - not running hot - but these round disk are part of the heat exchanger for the transmission cooling. If you notice the line into the back of radiator where the disks are come from the transmission for cooling. Being exposed to the hot air the antifreeze was not able to carry off the heat because the disks were not covered.

Replacing my radiator with a Modine radiator not a cheap replacement model did help but didn't solve the problem - the temperature took longer to reach the 185 level - also if I was driving hard then lightened up on the pedal the temperature would decrease - old radiator temperature got high stayed high.
I intend to add a trans cooler not sure which one probably a BM to keep temperature down some more.

I do believe my transmission is the problem - cause by heat build up. Could be a torgue convertor or solenoid or out tolerance part or PCM problem.

Unfortunately I don't want to lay up my car because I commute 100 miles daily and anything more than a day without transportation is a real pain. So that is why a cooler might keep cool enough to avoid PCM shutting off TCC lockup.

PS: If your OD is shutting off you can reset while driving by just shut ignition off and on (don't engage starter) real quick while in gear the TCC lockup will engage and OD will resume but doesn't last too long. There is no need to shift into neutral to shut car off hust flick the key and keep driving.

i second your thought that it could be heat related.

Mine only slips in the hot summer months, and when I added a trans cooler it helped alot, but did not totally solve the problem. It was more of a bandaid that minimized the problem.

I have been dealing with this for a year now, and am still reading closely everyones thoughts on this problem.

I am more and more convinced it is a trans problem of some sort. That increases with temp. When cold it will not do the surging. But, will get worse as the temp increases, and slight increase on the accelarator. A simple bump to the brake will stop it. A heavy punch to the accelarator will reduce it, and almost eleiminate it.

Recently when cold, put into drive I could easily tell the trans was slipping. I have yet to determine if this is the trans or torque converter.

Time will tell, and I will keep reading. :?

it could be something in the tranny going bad, a valve or something. These transmissions are so damn complicated, makes me wish I had a manual.