Another SC400 with A340e shift issues
10-05-12, 01:36 AM
#1
Another SC400 with A340e shift issues
(Disclaimer. Before I start please allow myself to say that yes, I did do a search on this entire subject. Also, my bad knees do not allow me to drive manual, so please do not suggest I do a manual swap)
Ok, so my 1992 SC400 has had issues with the trans since I bought her. Hopefully someone here can confirm to me that my issues are in fact related to the notorious shift solenoids.
In open loop operation, the transmission smooths flawlessly. No issues at all. However, when the engine reaches closed loop temperature, the transmission randomly begins to lug the engine as if the torque converter locks up too early (highway driving and city driving). I have to manually shift down to 2 to have some decent acceleration. Also, when I accelerate from a complete stop, it occasionally lugs the engine while shifting from 1st to 2nd. Feels as if the torque converter is locking up too early and I then too have to downshift into 2 to be able to accelerate. This occurs with Overdrive both on and off. I also would try to turn off overdrive whenever I would experience these issues to try to get it to downshift during highway driving and it does not disengage. Feels as if the torque converter is still locked up (possibly some sort of fail safe mechanism???) The Overdrive light would flash when I would experience these symptoms until I adjusted the throttle position sensor. The transmission would also slam hard into Reverse and Drive on cold start ups. I did research on that issue and found out about adjusting the Throttle Position Sensor (Thank you to OLT for that post. Very informative), which cured my cold transmission gear slamming. Now ever since I've done that adjustment the transmission has still had its shifting issues, but the blinking Overdrive light is no more. I have checked the ECU for transmission codes but none are ever found.
Other issues are also occasional late 1-2 shifts (revs up to about 3500-4000 rpm before it shifts. ECT PWR is off.)
So my question is, do my symptoms justify the replacement of the shift solenoids? Any steps to confirm that the solenoids are no longer any good (such as checking resistance?) I'm inclined to open up the oil pan and service the transmission without replacing these solenoids only to find out that the solenoids are indeed toast and have to perform double labor. Thanks guys!
Ok, so my 1992 SC400 has had issues with the trans since I bought her. Hopefully someone here can confirm to me that my issues are in fact related to the notorious shift solenoids.
In open loop operation, the transmission smooths flawlessly. No issues at all. However, when the engine reaches closed loop temperature, the transmission randomly begins to lug the engine as if the torque converter locks up too early (highway driving and city driving). I have to manually shift down to 2 to have some decent acceleration. Also, when I accelerate from a complete stop, it occasionally lugs the engine while shifting from 1st to 2nd. Feels as if the torque converter is locking up too early and I then too have to downshift into 2 to be able to accelerate. This occurs with Overdrive both on and off. I also would try to turn off overdrive whenever I would experience these issues to try to get it to downshift during highway driving and it does not disengage. Feels as if the torque converter is still locked up (possibly some sort of fail safe mechanism???) The Overdrive light would flash when I would experience these symptoms until I adjusted the throttle position sensor. The transmission would also slam hard into Reverse and Drive on cold start ups. I did research on that issue and found out about adjusting the Throttle Position Sensor (Thank you to OLT for that post. Very informative), which cured my cold transmission gear slamming. Now ever since I've done that adjustment the transmission has still had its shifting issues, but the blinking Overdrive light is no more. I have checked the ECU for transmission codes but none are ever found.
Other issues are also occasional late 1-2 shifts (revs up to about 3500-4000 rpm before it shifts. ECT PWR is off.)
So my question is, do my symptoms justify the replacement of the shift solenoids? Any steps to confirm that the solenoids are no longer any good (such as checking resistance?) I'm inclined to open up the oil pan and service the transmission without replacing these solenoids only to find out that the solenoids are indeed toast and have to perform double labor. Thanks guys!
01-04-15, 12:26 AM
#2
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[QUOTE=In open loop operation, the transmission smooths flawlessly. No issues at all. However, when the engine reaches closed loop temperature, the transmission randomly begins to lug the engine as if the torque converter locks up too early (highway driving and city driving). I have to manually shift down to 2 to have some decent acceleration.[/QUOTE]
I have the same issue. Weird torque converter lockup, and have to shift into 2nd when slowing for a stop light. In my case, I followed the service manual and replaced the TPS and 2ndary speed sensor. But, it is a 1994 SC400 with 333k miles. The issue is my wife drove this car cross country a couple times so it has the "bond" thing going for it. I think the answer is obvious- after 6000 engine hours the transmission is shot. I tried fluid change (16 quarts so far) and 2 filter changes in 3 months. Metal on the magnets after 3 months / 1000 miles. Anyhow l'm bringing mine to a transmission shop recommended by my mechanic. Engine still has factory compression, 185 across all 8 cylinders and no issues there. Rear main seal leaks, well I guess we can finally fix that.
I have the same issue. Weird torque converter lockup, and have to shift into 2nd when slowing for a stop light. In my case, I followed the service manual and replaced the TPS and 2ndary speed sensor. But, it is a 1994 SC400 with 333k miles. The issue is my wife drove this car cross country a couple times so it has the "bond" thing going for it. I think the answer is obvious- after 6000 engine hours the transmission is shot. I tried fluid change (16 quarts so far) and 2 filter changes in 3 months. Metal on the magnets after 3 months / 1000 miles. Anyhow l'm bringing mine to a transmission shop recommended by my mechanic. Engine still has factory compression, 185 across all 8 cylinders and no issues there. Rear main seal leaks, well I guess we can finally fix that.
04-24-16, 01:52 PM
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(Disclaimer. Before I start please allow myself to say that yes, I did do a search on this entire subject. Also, my bad knees do not allow me to drive manual, so please do not suggest I do a manual swap)
Ok, so my 1992 SC400 has had issues with the trans since I bought her. Hopefully someone here can confirm to me that my issues are in fact related to the notorious shift solenoids.
In open loop operation, the transmission smooths flawlessly. No issues at all. However, when the engine reaches closed loop temperature, the transmission randomly begins to lug the engine as if the torque converter locks up too early (highway driving and city driving). I have to manually shift down to 2 to have some decent acceleration. Also, when I accelerate from a complete stop, it occasionally lugs the engine while shifting from 1st to 2nd. Feels as if the torque converter is locking up too early and I then too have to downshift into 2 to be able to accelerate. This occurs with Overdrive both on and off. I also would try to turn off overdrive whenever I would experience these issues to try to get it to downshift during highway driving and it does not disengage. Feels as if the torque converter is still locked up (possibly some sort of fail safe mechanism???) The Overdrive light would flash when I would experience these symptoms until I adjusted the throttle position sensor. The transmission would also slam hard into Reverse and Drive on cold start ups. I did research on that issue and found out about adjusting the Throttle Position Sensor (Thank you to OLT for that post. Very informative), which cured my cold transmission gear slamming. Now ever since I've done that adjustment the transmission has still had its shifting issues, but the blinking Overdrive light is no more. I have checked the ECU for transmission codes but none are ever found.
Other issues are also occasional late 1-2 shifts (revs up to about 3500-4000 rpm before it shifts. ECT PWR is off.)
So my question is, do my symptoms justify the replacement of the shift solenoids? Any steps to confirm that the solenoids are no longer any good (such as checking resistance?) I'm inclined to open up the oil pan and service the transmission without replacing these solenoids only to find out that the solenoids are indeed toast and have to perform double labor. Thanks guys!
Ok, so my 1992 SC400 has had issues with the trans since I bought her. Hopefully someone here can confirm to me that my issues are in fact related to the notorious shift solenoids.
In open loop operation, the transmission smooths flawlessly. No issues at all. However, when the engine reaches closed loop temperature, the transmission randomly begins to lug the engine as if the torque converter locks up too early (highway driving and city driving). I have to manually shift down to 2 to have some decent acceleration. Also, when I accelerate from a complete stop, it occasionally lugs the engine while shifting from 1st to 2nd. Feels as if the torque converter is locking up too early and I then too have to downshift into 2 to be able to accelerate. This occurs with Overdrive both on and off. I also would try to turn off overdrive whenever I would experience these issues to try to get it to downshift during highway driving and it does not disengage. Feels as if the torque converter is still locked up (possibly some sort of fail safe mechanism???) The Overdrive light would flash when I would experience these symptoms until I adjusted the throttle position sensor. The transmission would also slam hard into Reverse and Drive on cold start ups. I did research on that issue and found out about adjusting the Throttle Position Sensor (Thank you to OLT for that post. Very informative), which cured my cold transmission gear slamming. Now ever since I've done that adjustment the transmission has still had its shifting issues, but the blinking Overdrive light is no more. I have checked the ECU for transmission codes but none are ever found.
Other issues are also occasional late 1-2 shifts (revs up to about 3500-4000 rpm before it shifts. ECT PWR is off.)
So my question is, do my symptoms justify the replacement of the shift solenoids? Any steps to confirm that the solenoids are no longer any good (such as checking resistance?) I'm inclined to open up the oil pan and service the transmission without replacing these solenoids only to find out that the solenoids are indeed toast and have to perform double labor. Thanks guys!
I know this is old but I'm having this exact problem did anyone ever figure out what was going on???
05-17-16, 06:22 PM
#5
My auto. tranny just started doing the holding the 1-2 shift, only first thing when its cold. Worse thing is it bangs into drive everytime you first put it into gear. Iv heard TPS affects trans. shifting characterists, maybe time for a new one. $125.00 to find out.
Last edited by bigwhite; 05-17-16 at 06:30 PM.
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