Manually shut off torque converter?

[00GTP4ME]

I've read a few places that people have been able to wire a switch to the brake switch so that they can manually control when/if the torque converter locks up or not. Has anyone done that on a Grand Prix and/or does anyone know how that would be done on our cars?

[Tech II]

OK, I'll bite....why in the world would you want to do that?

[00GTP4ME]

Because I'm desperate, poor, and out of ideas, how's that?

I'll see if I can condense this for you as much as possible...

In Feb of this year I had the tranny rebuilt and that included a warranty. Well about mid August I started noticing what was a slight jerking sensation while going up a hill (really hard to describe, but it felt like an engine miss or a tranny prob). It got worse and worse and so bad that I thought for sure it was the trans. I took it in to the shop and they said tranny checked out just fine. Took it to a dealership to figure out what WAS going on and they said bad torque converter. Took it to another tranny shop for a 2nd opinion and they also said bad torque converter. Took it back to original shop and they swear up and down nothing is wrong with the trans.
I did a bunch of research and decided to replace the TPS. That solved HALF my problem. Before the TC was engaging way too soon along with the jerking feeling I got. Well now the TC seems to want to engage when it's supposed to with a new TPS, but it still bucks and jerks.
I have no DTC's, no tranny codes, and I've checked everything I can think of. Tranny is under warranty, but "the" tranny shop swears nothing is wrong with it. Anyone else wants to charge me $1K for a CHANCE that it might fix my prob. (If not, I'm stuck with a $1K bill and my car runs no differently and I can't afford that). So while the car still runs, I'm just going to keep driving it until I stumble upon the problem, or something breaks. Once something breaks, it will be much easier to figure out what the crap is going on. If it really is the trans, I'm not out anything. If it's the motor, I'm hosed.
But anyway, if I can keep the TC from locking up, the car runs as smooth as butter. So there ya go. Believe it or not, that is the VERY short version. Right now I HATE this car and I keep hoping someone hits it....hard.

[Tech II]

Are you sure it's not an engine miss?

[Stealthee]

Originally Posted by Tech II

Are you sure it's not an engine miss?

This is what I am thinking. If its only under load it sounds like a misfire and has nothing to do with the transmission.

[00GTP4ME]

I would love for it to only be an engine miss. I had an engine miss a while back that was bad spark plug wires, but it wasn't like this.
But I've replaced my wires with new ones, I've checked the plugs twice, checked the coils (inspected the prongs which looked fine with no corrosion), greased everything, sprayed with water and looked for sparks, cleaned the MAF, is there anything else I can check?

[Stealthee]

Replace the plugs. Just checking them may not be suffecient. There could be a hairline crack or something causing a misfire under load. I had an issue on my Stealth where it would only miss going up hills and ran fine in every other form of driving. When I went to check plugs, one had a crack in the porcelin.

They are cheap, and the worst case scenario is it doesn't fix your issue. But at least you'll have eliminated something.

[olopezm]

You can rule out a bad injector by unplugging one at a time, pay special attention, and listening to the idle speed (it should drop). If it doesn't then that injector has a problem, all injectors should cause RPM's to drop the same.

Have you checked the fuel pressure at the injector rail?.

Just to clarify when you say you greased everything, what did you actually grease? Spark plug wire boots or the actual prongs?.

Oscar.

EDIT You can try adding a bottle of lubegard to the transmission, this is a must for some ford transmissions in order to eliminate TC shudder, if that really is your problem then the additive should help if it's not it won't harm.

[00GTP4ME]

Originally Posted by Stealthee

Replace the plugs. Just checking them may not be suffecient. There could be a hairline crack or something causing a misfire under load. I had an issue on my Stealth where it would only miss going up hills and ran fine in every other form of driving. When I went to check plugs, one had a crack in the porcelin.

They are cheap, and the worst case scenario is it doesn't fix your issue. But at least you'll have eliminated something.

I suppose I could change the plugs again and you're right they're not much. When I had a misfire last time it was a little tear in the spark plug wire insulation.

If I do change the plugs and it has no affect, can I put the current ones back in?

Originally Posted by olopezm

You can rule out a bad injector by unplugging one at a time, pay special attention, and listening to the idle speed (it should drop). If it doesn't then that injector has a problem, all injectors should cause RPM's to drop the same.

Have you checked the fuel pressure at the injector rail?.

Just to clarify when you say you greased everything, what did you actually grease? Spark plug wire boots or the actual prongs?.

Oscar.

EDIT You can try adding a bottle of lubegard to the transmission, this is a must for some ford transmissions in order to eliminate TC shudder, if that really is your problem then the additive should help if it's not it won't harm.

I haven't checked anything related to fuel. I change the fuel filter yearly though. I can try checking the injectors too. When I did the plugs and wires I put dielectric grease on the inside of the boots and where they connect (on the prongs) of the spark plugs and on the coils.

Not long after the trans was rebuilt I put in a bottle of the lucas trasmission additive.

BTW, I really appreciate the suggestions guys - much appreciated.

[Tech II]

We are going round and round on this......when you went to the dealership to check this out, did they attach a Tech II and road test it?

While looking at data when this happened, they could verify if it was a misfire or a shudder....

[00GTP4ME]

Yes, as I recall, the dealership did hook a Tech II to it and road test it. They said they could see the TC slipping. According to their print-out they gave me, they said:

"Test drove vehicle and duplicated customer concern. Condition would happen TCC apply in third and fourth gears. Inspected for stored DTC's and no DTC's were found. Check for programming updates and no updates were found. Diagnosed internal transmission problem with TCC apply circuits, faulty TCC solenoid or faulty torque converter clutch. Reflashed computer as per customer, no change."

As I mentioned, the first place I went to when this issue came up was my tranny shop. He noted that the TC was engaging way too early, bogging the engine, the engine would sense that, release the torque converter, then think conditions were right to engage, re-engage, bog, and so forth. He said this is a computer control issue. Go get it flashed at a dealer and you should be good. I have a tuned PCM and didn't want that to be messed with so I put my factory original PCM back in (one to preserve my tune, and two to see if my tuned PCM maybe had a glitch). Test drove with my factory PCM and it made no difference , but I left it in for the time being. I also put on a brand new set of plug wires since that caused my miss in the past. As I was taking the #6 wire off the plug/boot snapped off the wire so I was all excited thinking I found the issue. Put on new wires. No affect.

So I took it to a dealer and they said what I posted above. With this info from the dealer, I went back to my tranny guy and he pretty much lost it on me and just short of accused the dealer of lying through their teeth. He very energetically insisted nothing was wrong with the transmission and that he was 100% certain there wasn't. He said that he knew it was a control issue because he hooked my car up to a "Super Shifter," a device that takes complete control of the transmission's function and was able to command shifting, lock-up etc. He said with this device the transmission behaved flawlessly. Once control was given back to the vehicle, the problem returned. He also said that during his original test drive the SES light came on with a misfire code but then turned off (he couldn't give me the exact code). He said that his 37 years experience in nothing but transmissions made him 100% positive it was NOT the transmission causing my problem.
The dealer didn't flash my PCM right away but my tranny guy kept insisting that was the problem so I told the dealer to flash it anyway (just to shut the tranny shop up pretty much). So they flashed it - no affect, $114 down the tube. Told my tranny shop and he said he doesn't believe they flashed it.

So I had the dealership and my tranny guy completely disagreeing with each other and I had no clue who to go with. The dealership couldn't guarantee me that their diagnosis was 100% accurate until they tore into the transmission and whether they turned out to be right or wrong, I was on the hook for a very expensive bill and I couldn't afford to pay for guesses. So I did more research and found this:

Engine Controls - Intermittent Chuggle/No DTC's Set

Bulletin No.: 05-06-04-058

Date: September 07, 2005

TECHNICAL
Subject:
Intermittent Chuggle or Fishbite on Light Acceleration or at Highway Speeds with No Diagnostic Trouble Codes (DTCs) (Replace Throttle Position (TPS) Sensor)

Models:
1995-1999 Buick Riviera
1995-2004 Buick Regal
1995-2005 Buick LeSabre, Park Avenue
1997-2005 Buick Century
1995-2001 Chevrolet Lumina
1995-2002 Chevrolet Camaro
1995-2005 Chevrolet Monte Carlo
2000-2005 Chevrolet Impala
1995-1997 Oldsmobile Cutlass Supreme, Ninety Eight
1995-1999 Oldsmobile Eighty Eight
1998-2002 Oldsmobile Intrigue
1995-2002 Pontiac Firebird
1995-2003 Pontiac Grand Prix
1995-2005 Pontiac Bonneville

with 3800 V6 Engine (VIN K - RPO L36)

Condition

Some customers may comment on an intermittent chuggle or fishbite on light acceleration or at steady-state highway speeds (typically 80-105 km/h [50-65 mph]) with no PCM DTCs set. This condition may lead the technician to suspect the TCC circuit or torque converter.

Cause

This condition may be caused by intermittent operation of the Throttle Position (TPS) Sensor.

Correction

In observed cases, the Tech 2(R) is not fast enough to consistently detect this condition during a snapshot. It is recommended to use a DVOM set to the min/max recording mode. Connect the DVOM at the TPS connector (positive lead to TPS feedback signal pin and negative lead to TPS ground pin). Duplicate this condition by driving the vehicle. If the voltage dropout (less than 0.45 v) is recorded on the DVOM, replace the TPS sensor and re-evaluate the vehicle before continuing with other driveability or transmission diagnosis.


So I changed my TPS and voila - the early engaging TC issue went away. Bucking/jerking still remained. I called my tranny guy, told him the story, and it didn't change his opinion whatsoever. Still not the tranny.

So I took the car to a second tranny shop for another opinion. They came up with the same conclusion as the dealership. Per their print-out:

"4 mile road test shows that transmission is shifting through all gears at this time. TCC duty cycle stays around 40 RPM but slips and goes down to near 0 RPM, then slips up to near 200 RPM. TCC cycled continuously through the road test within those parameters. There are no codes present at this time. Transmission fluid level is ok and fluid is clean. Recommend remove transmission and torque converter. Cut converter open and inspect."

So I gave my tranny guy another update and he still didn't care. He offered to have me come in and said he would go on a road test with me and let me watch the scanner myself. So I did. Of course I had no clue what I was looking at but he explained that the TC% was the % that the TC was locked up (the higher the percent the less slippage was allowed). There was also a TCC RPM that he had me watch, but I never really understood what this was. He took us in the hills near his shop on some very very steep grades and the car was bucking all over the place but it didn't seem to have an effect on the TC% that I could tell. I also noted that the TCC RPM seemed to go all over the place, but never went above 100 or at least not very much. He said that if the TC was slipping, that number would be three times what I was seeing.

So we finished the road test and he said he's still convinced the trans is fine and he was pretty sure my issue was an engine miss. I took the car home and checked the wires - fine, checked the plugs - fine, put dielectric grease on plugs and boots, checked the coils(prongs) - no corrosion and looked clean, put my tuned PCM back in, cleaned the MAF, all had no affect.

I'm no professional and I don't know who is right yet. It's two to one against my tranny shop, but he could still be right. I really don't care who's right, I just want my stupid car fixed.

[maxwedge]

If this is truly a miss, a scan under the misfire conditions would show mis -fire counts confirming it is actually a misfire causing the condition. Bad o2 sensor, low fuel pressure, dirty injectors or secondary ign problems can cause the symptoms particularly under load with the tcc engaged. If the trans is kicked out of lock up usually the misfire will go away as the engine is not under load, this can fool a lot of techs.

[00GTP4ME]

Originally Posted by maxwedge

If this is truly a miss, a scan under the misfire conditions would show mis -fire counts confirming it is actually a misfire causing the condition. Bad o2 sensor, low fuel pressure, dirty injectors or secondary ign problems can cause the symptoms particularly under load with the tcc engaged. If the trans is kicked out of lock up usually the misfire will go away as the engine is not under load, this can fool a lot of techs.

That's another frustration I have. My usual mechanic is someone who has proved to be very trustworthy/competent in the past, and I've called him three times explaining the situation and he just turns me away saying without a CEL, there's not much he can do and that the dealership would have better diagnostic equip than he would. I wish he'd at least give it a shot because I don't think he's giving himself enough credit. He seems like he wants nothing to do with it though.

It is not hard at all to be in the misfire conditions. As long as the car is in 3rd or 4th gear (it may even do it in 2nd, but I'm not 100% positive) and you're not coasting downhill, it jerks and bucks and is very very noticeable. Heck, how much is a decent scanner that can read something like that? Maybe I should just go get my own, I don't know.

[olopezm]

I don't think using dielectric grease on the prongs is a good idea. It happened to me once and the results were bad, the car would lack of power. After cleaning them and using grease ONLY on the inner part of the boots OR around the porcelain part on the plug.

After all, grease only helps to prevent contamination or corrosion and doesn't helps to improve current flow, it actually is supposed to stop it.

About the scanner I've seen two Craftsman's avaable from sears, they seem to be good as both read transmission codes. The latest model is even supposed to read SRS and ABS system codes. You can look them up at the sears website.

Oscar.

[00GTP4ME]

Good to know. Maybe when I replace the plugs I'll just leave them alone and let the remaining grease inside the current boots do the work and call it good.