1991 Accord LX Idle/Shift Problems

[kevindadams]

I have a 1991 Accord LX. Recently I noticed it didn't want to change gears byitself (automatic). But you could change manually. I realized that the transmission computer under the passenger foot rest has burnt up. So I replaced it. Now the only problem I have is at idle (park or neutral) the car revs from 1000 - 3000 rpm slowly (up and back down approx. 4sec.) when you first start the vehicle. If you shift to reverse or park it stops the reving but shifts very hard. If you stop at a red light it revs again but this time quicker (up and down in 1 sec). What can cause this. SOmeone told me the throttle control sensor is the cause of this. I don't know. HELP!!!!

[ebpda9]

it sounds to me like the throttle position sensor and/or the idle control valves are out. did u just take the ecu out and threw a new one in ? do u have any S lights flashing in the dash ?

[vtracer20]

i also had something similar to the reving when my water gasket temp senor or what ever it is was left open....i replaced it and it fixed the problem....

[kevindadams]

I did swap out the AT (auto tranny) Control Box beside the computer. But the main ECU is still original. Where can I find the Water Gasket Temp at on the engine. Thanks

[kevindadams]

My S light was flashing but after installing the new AT Control unit the light stopped.

[kevindadams]

Is this the same as a colant temp sensor. A few times lately my temp guage says the car is running hot but the actual temp when you touch it is no more than usual. Thanks

[ebpda9]

Originally posted by kevindadams
My S light was flashing but after installing the new AT Control unit the light stopped.


hmm weird. i know the 92-93 have the atcu in the ecu and also the atcu is resposible for the ac clutch, and some other thing there. well the rough shifting is caused maybe by a burnt solenoid from the tranny ( it has 4) as for the idle i say you might have a vacuum leak too, or an idle set too high.