1986.5 A/T up-shifting at 4250, down-shifting at about 2750?

M47R1X · 07-09-2012, 02:49 AM

Hello, all! I had bought for my wife a few months back a 1986.5 black Supra with an automatic transmission (about 230k miles, garage kept 7MG-E, blah blah blah) that had a power steering leak, burns a wee bit of oil every now and then, but at the time, no other known issues. I had purchased this in Dallas and drove it back up to OKC and ran fine for the first day, then started dogging, stalling at lights, etc. Turns out that one of the stems from I think the BSV (going by memory, here: this was a few months back. You know, the little blue-green thing on the side of the radiator) was broken and was bypassed. I replaced that, and the car started running normal... ish. It still dogs down every now and then, but not nearly as bad.

With that out of the way, I replaced the high-pressure power steering line (which was a real b****, by the way. Manual never said I had to lift the rack, as the old hose was a two-piece system with replacement hoses all being one piece). I managed to pinch a bit of the line and will probably have to replace it. Again. I can't wait.

Now, for what the title says. My wife called me while she was driving it a day or two later saying that something else was wrong. The car was waiting to shift until over 4k RPM, and when it did, boy was it rough. Once it shifted, it would downshift just under 3k RPM: again, quite roughly. Now, in my RX-8, that'd be normal, but it definitely isn't normal here. It's between every single gear at about 4250 RPM. I tried turning overdrive off, set the ECT to sport (which worsened the problem by upping it to nearly 5k RPM to upshift), I even replaced the ECT computer, and none of it has helped.

I have the shop manual for the car and performed several of the diagnostics, and it really seemed that replacing the ECT computer would fix the problem. If I had the manual on me right now, I could tell you what all tests I did, but I can say that taking out the ECT computer and manually shifting at 2500 or so felt relatively smooth: not nearly as rough. This was what led me to replace the ECT computer in the first place.

It's somewhat driveable at the moment, but I don't want to take my chances on an engine with that many miles. Searching hasn't helped much. Thanks for any help, and I hope I didn't forget anything.

07-09-2012, 02:49 AM	#1
M47R1X Stock Join Date: Jul 2012 Location: OKC, OK Posts: 5	1986.5 A/T up-shifting at 4250, down-shifting at about 2750? Hello, all! I had bought for my wife a few months back a 1986.5 black Supra with an automatic transmission (about 230k miles, garage kept 7MG-E, blah blah blah) that had a power steering leak, burns a wee bit of oil every now and then, but at the time, no other known issues. I had purchased this in Dallas and drove it back up to OKC and ran fine for the first day, then started dogging, stalling at lights, etc. Turns out that one of the stems from I think the BSV (going by memory, here: this was a few months back. You know, the little blue-green thing on the side of the radiator) was broken and was bypassed. I replaced that, and the car started running normal... ish. It still dogs down every now and then, but not nearly as bad. With that out of the way, I replaced the high-pressure power steering line (which was a real b**, by the way. Manual never said I had to lift the rack, as the old hose was a two-piece system with replacement hoses all being one piece). I managed to pinch a bit of the line and will probably have to replace it. Again. I can't wait. Now, for what the title says. My wife called me while she was driving it a day or two later saying that something else was wrong. The car was waiting to shift until over 4k RPM, and when it did, boy was it rough. Once it shifted, it would downshift just under 3k RPM: again, quite roughly. Now, in my RX-8, that'd be normal, but it definitely isn't normal here. It's between every single gear** at about 4250 RPM. I tried turning overdrive off, set the ECT to sport (which worsened the problem by upping it to nearly 5k RPM to upshift), I even replaced the ECT computer, and none of it has helped. I have the shop manual for the car and performed several of the diagnostics, and it really seemed that replacing the ECT computer would fix the problem. If I had the manual on me right now, I could tell you what all tests I did, but I can say that taking out the ECT computer and manually shifting at 2500 or so felt relatively smooth: not nearly as rough. This was what led me to replace the ECT computer in the first place. It's somewhat driveable at the moment, but I don't want to take my chances on an engine with that many miles. Searching hasn't helped much. Thanks for any help, and I hope I didn't forget anything. Last edited by M47R1X; 07-09-2012 at 05:40 AM.