I am having a really bad time figuring this one out - the resolution to the problem will not be found easily over the internet - however, I have no other options. There have been far too many people that have guessed at this or that and I've put close to $900 in parts alone, at cost, into this freakin' problem.
Be forewarned, this baby is not for the weak - it is for the truly gifted Supra insaniacs that know more then probably the very engineers that created the beast...
First, a little background - this is an 87 Turbo w/automatic and 75,000 miles, all stock, never raced and the VERY best maintenance record known to mankind ... or ... suprakind. It is not driven hard but I've had "fun" with it over the years. It is not throwing any codes, all vacuum lines, by site, have been checked and rechecked, there are no leaks whether liquid or air anywhere in any line that we can find with our eyes or squirt bottle with liquid soap... the tranny fluid is fresh, the tranny works perfectly, and through this process of trying to find a solution, gave the Supra a full tune-up with fresh plugs - everything with respect to operation and maintenance is perfect, everything works as if it should from the factory...
Okay, let's do this - here's the problem - a two part problem that MIGHT be related, you tell me...
I will begin with what the car is doing and then tell you what we did to address the issue without solution...
During normal acceleration, the throttle is smooth as silk. If I punch it, something is happening whereby activating a resistance in the throttle. Resistance? Yes, after punching it, something happens and causes the throttle to become VERY difficult to push down all the way. At about 3/4 of the way to the floor from full up, the resistance becomes so great that I have to "force" with great pressure, the pedal all the way down. As soon as I do so, the tranny generally and immediately kicks down a gear, boost builds up and I'm on my way quickly.
If I drive it without quickly mashing the pedal, this phenomenon never takes place...
I have found that if I place the car in neutral, allow the rpm to drop to idle, essentially disconnecting the tranny from the engine, then blip the throttle a few times, it goes back to normal operation UNTIL I mash it again and instantly the phenomenon starts up again.
What have I done to this point to find a solution?
* ensured the carpet is not in the way of the throttle pedal assembly
* checked the linkage
* replaced the linkage
* rechecked the linkage
* removed plenum
* inspected "butterfly valve" and complete throttle assembly
* checked freeplay
* removed and replaced cruise control
* replaced exhaust for fear of some weird back-pressure gremlin (part of the cat had come apart and was floating around in there)
* replaced TPS
* R*R tranny fluid and filter with complete torque converter drain and fill
* inspected tranny fluid carefully and had it paper filtered looking for anything that might be wrong inside the tranny.
THE PROBLEM STILL EXISTS...
The last thing I think it might be???
Well, having had three certified Toyota techs, two tranny shops, two automotive ASE techs, myself spending untold hours researching this problem on the forums and finally downloading the classroom texts used to teach tranny techs and Toyota techs about the Aisen A340E, or 30-40LE, transmission - I think it just might be the mechanism that the kickdown/line pressure cable operates. Oh yeah, I also replaced the kick down cable.
Remember, having the techs review this problem doesn't mean they are goobers, they were all young and some maybe born the same year my Supra was... Their exposure to this tranny is not uncommon as it is used is many many cars and trucks out there - both foreign and domestic. Some are altered a little for AWD, 4x4, FWD, performance (MKIV) et al... the A340E is a popular and VERY reliable tranny, if taken care of.
Why do I think that is my only hope Obe Wahn? Because I think there might be some type of burr inside the valve body - or more specifically, inside the cylinder of which the "plunger" or "kick down mechanism" resides and it is catching during hard acceleration. OR... maybe it is loose? It only take a few thousanths of an inch inside those tight tolerances to knock it out of whack...
Whoa, not done yet... it does one other thing that is odd. The revs, on decel while letting the car slow from 55 to 45, oscillates from 1500 to 2200 rpm and causes the car to sort of lurch - or opposite of lurch, the breaking horsepower is greater and then not as great so it sort of coasts and slows and coasts and slows. I also experienced this twice when I started the car, therefore, I thought TPS... replaced it with a new one (the old one tested bad) and though the oscillation at idle is gone, it still does so when either slowing with foot off the throttle from 55 to 45 OR when my foot is barely, ever so lighting touching the throttle while trying to maintain 45mph - again, this happens with or without cruise control connected. This is annoying because much of my driving on the city streets is focused at that speed...
There you have it - if there are other venues I've not looked at OR if you think something I've already done could be redone another way. Please, I am groveling here, let me know. Show forth thine wisdom and let me once again live in peace and harmony with my MKIII...
Seriously, if someone could give me help, that would be just way too cool.
Dez
Be forewarned, this baby is not for the weak - it is for the truly gifted Supra insaniacs that know more then probably the very engineers that created the beast...
First, a little background - this is an 87 Turbo w/automatic and 75,000 miles, all stock, never raced and the VERY best maintenance record known to mankind ... or ... suprakind. It is not driven hard but I've had "fun" with it over the years. It is not throwing any codes, all vacuum lines, by site, have been checked and rechecked, there are no leaks whether liquid or air anywhere in any line that we can find with our eyes or squirt bottle with liquid soap... the tranny fluid is fresh, the tranny works perfectly, and through this process of trying to find a solution, gave the Supra a full tune-up with fresh plugs - everything with respect to operation and maintenance is perfect, everything works as if it should from the factory...
Okay, let's do this - here's the problem - a two part problem that MIGHT be related, you tell me...
I will begin with what the car is doing and then tell you what we did to address the issue without solution...
During normal acceleration, the throttle is smooth as silk. If I punch it, something is happening whereby activating a resistance in the throttle. Resistance? Yes, after punching it, something happens and causes the throttle to become VERY difficult to push down all the way. At about 3/4 of the way to the floor from full up, the resistance becomes so great that I have to "force" with great pressure, the pedal all the way down. As soon as I do so, the tranny generally and immediately kicks down a gear, boost builds up and I'm on my way quickly.
If I drive it without quickly mashing the pedal, this phenomenon never takes place...
I have found that if I place the car in neutral, allow the rpm to drop to idle, essentially disconnecting the tranny from the engine, then blip the throttle a few times, it goes back to normal operation UNTIL I mash it again and instantly the phenomenon starts up again.
What have I done to this point to find a solution?
* ensured the carpet is not in the way of the throttle pedal assembly
* checked the linkage
* replaced the linkage
* rechecked the linkage
* removed plenum
* inspected "butterfly valve" and complete throttle assembly
* checked freeplay
* removed and replaced cruise control
* replaced exhaust for fear of some weird back-pressure gremlin (part of the cat had come apart and was floating around in there)
* replaced TPS
* R*R tranny fluid and filter with complete torque converter drain and fill
* inspected tranny fluid carefully and had it paper filtered looking for anything that might be wrong inside the tranny.
THE PROBLEM STILL EXISTS...
The last thing I think it might be???
Well, having had three certified Toyota techs, two tranny shops, two automotive ASE techs, myself spending untold hours researching this problem on the forums and finally downloading the classroom texts used to teach tranny techs and Toyota techs about the Aisen A340E, or 30-40LE, transmission - I think it just might be the mechanism that the kickdown/line pressure cable operates. Oh yeah, I also replaced the kick down cable.
Remember, having the techs review this problem doesn't mean they are goobers, they were all young and some maybe born the same year my Supra was... Their exposure to this tranny is not uncommon as it is used is many many cars and trucks out there - both foreign and domestic. Some are altered a little for AWD, 4x4, FWD, performance (MKIV) et al... the A340E is a popular and VERY reliable tranny, if taken care of.
Why do I think that is my only hope Obe Wahn? Because I think there might be some type of burr inside the valve body - or more specifically, inside the cylinder of which the "plunger" or "kick down mechanism" resides and it is catching during hard acceleration. OR... maybe it is loose? It only take a few thousanths of an inch inside those tight tolerances to knock it out of whack...
Whoa, not done yet... it does one other thing that is odd. The revs, on decel while letting the car slow from 55 to 45, oscillates from 1500 to 2200 rpm and causes the car to sort of lurch - or opposite of lurch, the breaking horsepower is greater and then not as great so it sort of coasts and slows and coasts and slows. I also experienced this twice when I started the car, therefore, I thought TPS... replaced it with a new one (the old one tested bad) and though the oscillation at idle is gone, it still does so when either slowing with foot off the throttle from 55 to 45 OR when my foot is barely, ever so lighting touching the throttle while trying to maintain 45mph - again, this happens with or without cruise control connected. This is annoying because much of my driving on the city streets is focused at that speed...
There you have it - if there are other venues I've not looked at OR if you think something I've already done could be redone another way. Please, I am groveling here, let me know. Show forth thine wisdom and let me once again live in peace and harmony with my MKIII...
Seriously, if someone could give me help, that would be just way too cool.
Dez
