Bad torque converter?
Thread Starter
Burning Brakes
Joined: Dec 2012
Posts: 788
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From: Rio Rico, AZ
Bad torque converter?
I've been having a problem with my 1989 vette stalling when I pull in into reverse or drive. Not all the time but often enough to make me crazy. Once it successfully gets into any gear I can go back to park, back to reverse or drive with no stalling. If I shut off the engine for a bit the problem comes back till I'm successfully back in gear. Today I stopped by a transmission shop, unrelated, and through our conversation told him about the stalling. He asked immediately about my torque converter. Said that one that if it's locking immediately (maybe I've gotten that backwards) it can cause the car to stall. Is that true?
When I had my 383 stroker installed I had bought a 2200 rpm stall converter. I've had this stall problem from the start. Tom Wong approached the stall problem from the tune side of things. Never found any smoking guns. Anyway, is the converter a possible problem? How to diagnose it without just pulling it and installing a new one?
Thanks, Went
When I had my 383 stroker installed I had bought a 2200 rpm stall converter. I've had this stall problem from the start. Tom Wong approached the stall problem from the tune side of things. Never found any smoking guns. Anyway, is the converter a possible problem? How to diagnose it without just pulling it and installing a new one?
Thanks, Went
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
The TC receives the lock signal from the ECM, in any case there is an electrical signal needed.
Pull the electrical connection to the TC just to test the backup problem.
Or hold the brake pedal down, as that disengages the TC lockup signal from the ECM.
Pull the electrical connection to the TC just to test the backup problem.
Or hold the brake pedal down, as that disengages the TC lockup signal from the ECM.
Melting Slicks
Joined: Mar 2002
Posts: 2,876
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From: Sligo PA
I'm wondering if it's not something internal in the trans. I remember there being an issue with the 700r4's and 4l60e's where it was either the reverse band or the main drum would hang up and cause this issue. I can't remember which one caused it but I know it happens.
I'm sure some of the members here that are more familiar with the 700r4 will chime in. I'm also wondering if it could be a solenoid in the vale body failing. If that's the case they are super easy to change.
I'm sure some of the members here that are more familiar with the 700r4 will chime in. I'm also wondering if it could be a solenoid in the vale body failing. If that's the case they are super easy to change.
Le Mans Master
Joined: Aug 2017
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From: New Jersey
I had an 83 caddy with a similar issue but never was able to narrow it down... what would happen was the TC would hang up... coming to a stop it would buck like a manual until it let loose or stall. Unplugging the brake switch was suggested and that made it occur all the time, meaning it was an issue with the TC iirc... I was 10 so its kind if hard to remember though. If I remember correctly driving below 45 mph, which is when TCC lock was fully commanded iirc, fixed it.
I'm curious, do you feel any pushing like it wants to go through the converter or anything? When one of the control valves in my 4l60 went I would get 1-2-3 then the truck would stay stuck in 3rd until it sat for a bit off. I would think at a cold start anything on that side could be ruled out and that it's something else... on my 67 when it had the "tight" converter dropping into reverse when cold would stall it. Even with the loose one it doesn't like it. I would trust your tuner though. He is held in fairly high regard around here from what I've read. Anything else odd about it to you though?
I'm curious, do you feel any pushing like it wants to go through the converter or anything? When one of the control valves in my 4l60 went I would get 1-2-3 then the truck would stay stuck in 3rd until it sat for a bit off. I would think at a cold start anything on that side could be ruled out and that it's something else... on my 67 when it had the "tight" converter dropping into reverse when cold would stall it. Even with the loose one it doesn't like it. I would trust your tuner though. He is held in fairly high regard around here from what I've read. Anything else odd about it to you though?
Melting Slicks
Joined: Feb 2003
Posts: 2,677
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From: Saskatoon Sask.
Its possible but not probable that it is electric. It would have to be a combination of two problems in order for this to happen. Even though the solenoid might be grounding out and activating, nothing would happen without signal oil. There is no signal oil to the coverter valve in reverse or 1st. Other considerations would be a sticking converter valve in the pump - broken spring in the pump - somehow or other, release oil being fed to the apply circuit.
Melting Slicks
Joined: Feb 2003
Posts: 2,677
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From: Saskatoon Sask.
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Melting Slicks
Joined: Mar 2002
Posts: 2,876
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From: Sligo PA
If it were my car and I wanted to fix it on a budget I would start with getting a solenoid and internal harness kit. Replace the filter while you're at it. A lot of trans electrical issues can be fixed with a new internal harness. If the problem doesn't go away then I would get a higher stall speed converter and swap it in. And if that doesn't work then a rebuild. But this way your worst case scenario is you end up with a fresh transmission, with all new electronics and a new higher stall converter.
Melting Slicks
Joined: Feb 2003
Posts: 2,677
Likes: 812
From: Saskatoon Sask.
If it were my car and I wanted to fix it on a budget I would start with getting a solenoid and internal harness kit. Replace the filter while you're at it. A lot of trans electrical issues can be fixed with a new internal harness. If the problem doesn't go away then I would get a higher stall speed converter and swap it in. And if that doesn't work then a rebuild. But this way your worst case scenario is you end up with a fresh transmission, with all new electronics and a new higher stall converter.
OK, let's try this a different way. The OP said his car stalls when he puts it in 1st. or reverse. Please indicate to me where the signal oil is even if the solenoid was firing.
Thread Starter
Burning Brakes
Joined: Dec 2012
Posts: 788
Likes: 160
From: Rio Rico, AZ
The transmission shifts feel normal once I'm going down the road. Shifts feel good leaving a stop light. When I put my foot in it it shifts down like I'd expect. It's just the initial pulling it into any gear after starting up. It doesn't seem to matter how warm the engine is or isn't. And...it isn't every time, at least when the engine is fully warmed up it isn't. It pretty much stalls every time when it's cold except if I don't feather the throttle a bit. Once I feather the throttle to get it into gear it won't stall again till the engine is off a while. I once had thought the 383 wasn't idling fast enough contributing to the stall. I set the idle up a bit in increments, reset the TPS. Higher idle never made a difference so I set the idle back to a lower RPM. Probably wasn't the correct tack to approach this with but wanted to see if it made a difference.
Went
Went
Le Mans Master
Joined: Feb 2005
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From: Clearwater Florida
..... You will need to confirm this with a 700R4 expert but I know that there is a converter clutch feed valve in the pump that can be accessed with the pan off ... years ago a friend and I rebuilt my 700 and I had the same problem ... as soon as I put it in any gear it would stall with a chirp from the tires ... it turned out that we had installed a spring on the wrong side of a valve ... My friend is the one who realized what had happened and he was also the one who cured it by pulling the valve from the pump and re-installing it ... perhaps yours is more of a sticking situation or possibly the wrong spring or worn pump body but that's where I would suggest you go first ... it'll only cost you a few quarts of trans oil ..... then there's that pesky little check ball in the end of the input shaft .....
Last edited by C409; Jan 31, 2021 at 08:35 AM.
Melting Slicks
Joined: Feb 2003
Posts: 2,677
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From: Saskatoon Sask.
..... You will need to confirm this with a 700R4 expert but I know that there is a converter clutch feed valve in the pump that can be accessed with the pan off ... years ago a friend and I rebuilt my 700 and I had the same problem ... as soon as I put it in any gear it would stall with a chirp from the tires ... it turned out that we had installed a spring on the wrong side of a valve ... My friend is the one who realized what had happened and he was also the one who cured it by pulling the valve from the pump and re-installing it ... perhaps yours is more of a sticking situation or possibly the wrong spring or worn pump body but that's where I would suggest you go first ... it'll only cost you a few quarts of trans oil ..... then there's that pesky little check ball in the end of the input shaft .....
.....
Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Went, I'm not sure if that's the cable in question, but holding down the brake pedal should disengage the lockup signal from the ECM.
My '89 FSM (pp 8A-20-2) shows that power to the TCC comes through the brake pedal switch. So depressing the brake pedal will (should) prevent power from getting from causing lockup. It is in fact the the ECM (A7-C2) that provides the ground to activate the TCC.
If it still stalls out the stalling problem would be due to another source or possibly the brake pedal sw (pp 8A-201-3C) is not properly set.
My '89 FSM (pp 8A-20-2) shows that power to the TCC comes through the brake pedal switch. So depressing the brake pedal will (should) prevent power from getting from causing lockup. It is in fact the the ECM (A7-C2) that provides the ground to activate the TCC.
If it still stalls out the stalling problem would be due to another source or possibly the brake pedal sw (pp 8A-201-3C) is not properly set.
Melting Slicks
Joined: Feb 2003
Posts: 2,677
Likes: 812
From: Saskatoon Sask.
Went, I'm not sure if that's the cable in question, but holding down the brake pedal should disengage the lockup signal from the ECM.
My '89 FSM (pp 8A-20-2) shows that power to the TCC comes through the brake pedal switch. So depressing the brake pedal will (should) prevent power from getting from causing lockup. It is in fact the the ECM (A7-C2) that provides the ground to activate the TCC.
If it still stalls out the stalling problem would be due to another source or possibly the brake pedal sw (pp 8A-201-3C) is not properly set.
My '89 FSM (pp 8A-20-2) shows that power to the TCC comes through the brake pedal switch. So depressing the brake pedal will (should) prevent power from getting from causing lockup. It is in fact the the ECM (A7-C2) that provides the ground to activate the TCC.
If it still stalls out the stalling problem would be due to another source or possibly the brake pedal sw (pp 8A-201-3C) is not properly set.
Last edited by arbee; Feb 1, 2021 at 08:07 AM.
Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
It does not get oil until the shift to 2nd.
So it would seem that even an errant lock-up signal from the ECM could not cause lock in 1 or R.
Could an error in the A4, either in assembly or from wear, provide the lockup fluid?
Melting Slicks
Joined: Feb 2003
Posts: 2,677
Likes: 812
From: Saskatoon Sask.
That too is my understanding that there can be TCC lockup only in 2,3,4 gears, though I was not familiar with the exact mechanism within the TC.
So it would seem that even an errant lock-up signal from the ECM could not cause lock in 1 or R.
Could an error in the A4, either in assembly or from wear, provide the lockup fluid?
So it would seem that even an errant lock-up signal from the ECM could not cause lock in 1 or R.
Could an error in the A4, either in assembly or from wear, provide the lockup fluid?
Exactly! Just to clarify, the switching is not in the TC, it is in the pump. The converter valve in the pump directs fluid to the apply side or the release side of the clutch through two separate passages. Solenoid actives - oil is sent to the converter valve, it strokes and line pressure is sent to the apply side. Solenoid shuts off - spring returns the converter valve and line feed is sent to the release side of the disk. The spring could be broken or the valve is getting hung up but the solenoid would have no effect in 1st. or reverse.