Making torque converter not locking up bellow 43 mph
03-07-2019, 09:36 AM
#1
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Join Date: Jun 2014
Location: Anaheim, CA
Posts: 138
Making torque converter not locking up bellow 43 mph
The car is a 97 auto GXE.
The most irritating thing about this slushbox is that under light throttle it shifts to 4th and locks up the torque converter even at 32 mph. When this happens, it lugs the engine at 1100 rpm, with all the wonderful things that does to motor mounts, bearing wear, noise, vibration and driveability. It takes more throttle to disengage the TC lockup, only for it to lock up again as you ease on the throttle. It even does this uphill, if the incline is not too great. What I end up doing is disable OD all together.
Another thing that's annoying about the TC lockup is that at higher speeds, say 60-65 mph, when the engine is spinning at 2000-2200 rpm, it's all too eager to unlock with not that much gas pedal input. It's like all this transmission cares about is throttle position, some substandard (IMO) shift logic was implemented.
It's also irritating how this transmission always wants to upshift; from a start, I let of the gas, the car starts rolling under idle power, gets some speed then shifts to second all without me touching the gas. If I keep a slow pace it will be in 3rd at 10 mph. Also, in stop and go traffic - from a stop I give it a tiny bit of gas to move, then of course I have to brake (it's SoCal), the stupid thing shifts to 2nd, making me brake harder; rinse and repeat.
One more annoying thing is that with a cold engine/transmission, only 1st and 2nd can do significant engine braking, in 3rd it can go to 70 mph at ~1300 rpm.
That about describes the problems.
I know there will be someone saying that this tranny has adaptive learning and I should stop driving like a granny, but it's not up to me, it's up to the cars I'm stuck behind. Or another guy saying how autos suck and I should get a manual - I agree, but it's what I have.
Ideally I would have the transmission reprogrammed with speed guides implemented: no upshift to 2nd bellow 15mph, no upshift to 3rd bellow 25 mph, no upshift to 4th bellow 35, no TC lockup in 4th bellow 45. Not sure that's possible and I'm not a programmer either. An option for hill mode would also be nice, with TC lockup in 3rd. Oh wait, I'm just describing a decent slushbox (say 04 Corolla).
But just getting the TC not to lockup bellow 43 mph would be a good start. Options for doing this that have crossed my mind:
1. Make the transmission think it's cold via a switch.
2. Disable TC lockup via a switch.
3. Your idea?
I'd appreciate any input
The most irritating thing about this slushbox is that under light throttle it shifts to 4th and locks up the torque converter even at 32 mph. When this happens, it lugs the engine at 1100 rpm, with all the wonderful things that does to motor mounts, bearing wear, noise, vibration and driveability. It takes more throttle to disengage the TC lockup, only for it to lock up again as you ease on the throttle. It even does this uphill, if the incline is not too great. What I end up doing is disable OD all together.
Another thing that's annoying about the TC lockup is that at higher speeds, say 60-65 mph, when the engine is spinning at 2000-2200 rpm, it's all too eager to unlock with not that much gas pedal input. It's like all this transmission cares about is throttle position, some substandard (IMO) shift logic was implemented.
It's also irritating how this transmission always wants to upshift; from a start, I let of the gas, the car starts rolling under idle power, gets some speed then shifts to second all without me touching the gas. If I keep a slow pace it will be in 3rd at 10 mph. Also, in stop and go traffic - from a stop I give it a tiny bit of gas to move, then of course I have to brake (it's SoCal), the stupid thing shifts to 2nd, making me brake harder; rinse and repeat.
One more annoying thing is that with a cold engine/transmission, only 1st and 2nd can do significant engine braking, in 3rd it can go to 70 mph at ~1300 rpm.
That about describes the problems.
I know there will be someone saying that this tranny has adaptive learning and I should stop driving like a granny, but it's not up to me, it's up to the cars I'm stuck behind. Or another guy saying how autos suck and I should get a manual - I agree, but it's what I have.
Ideally I would have the transmission reprogrammed with speed guides implemented: no upshift to 2nd bellow 15mph, no upshift to 3rd bellow 25 mph, no upshift to 4th bellow 35, no TC lockup in 4th bellow 45. Not sure that's possible and I'm not a programmer either. An option for hill mode would also be nice, with TC lockup in 3rd. Oh wait, I'm just describing a decent slushbox (say 04 Corolla).
But just getting the TC not to lockup bellow 43 mph would be a good start. Options for doing this that have crossed my mind:
1. Make the transmission think it's cold via a switch.
2. Disable TC lockup via a switch.
3. Your idea?
I'd appreciate any input
Last edited by marianm; 03-07-2019 at 10:16 AM.
10-29-2020, 09:44 PM
#5
Member
Thread Starter
Join Date: Jun 2014
Location: Anaheim, CA
Posts: 138
At this point I'm leaning towards cutting the wire that goes to number 5 in the photos (after the TCU connector) and installing a switch. I believe this should disable the TC lockup on demand (at least when the TCU commands that). Gotta do something about this, as last time I drove the car I got so pissed with all the lugging that I floored it after every stop for 30 minutes. Road rage is next...
Objections?
Objections?
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