Stock Auto transmission Delayed Shift to OD,Please help

[MSilva]

The Auto transmission in my 1992 has a abnormal delay before it will

shift into overdrive. It does this especially if you floor it. It wont go in to OD until about 70 mpg and sometimes not at all. If you drive easy it will usually shift into od, but sometimes you have to ease of the gas pedal to get it to shift into od. Shifts fine from 1st to 3rd. Does this mean it has to be rebuilt soon? I hope to avoid that. Maybe it needs an adjustment of some kind? Any opinions are greatly appreciated. Thanks, Marc

 

[cerberusiam]

Bottom side of the TPS where the TPS shaft goes into the throtle shaft for the injection pump is an adjustment to control how aggressive the shift to OD is. You can set it by feel or set the output of the TPS to specs to change the shift points. Also, inside the trans on the front corner of VB is another adjustment to speed up ans slow down the OD shift based on throttle pressure. Take a look in the readers rigs section and look for bushwakr's stuff he has an excellent set of pictures and instructions on how to set TPS. Have you turned your high idle screw up any of is this the first time you have worked on the truck?

 

[Philip]

The shift into OD is controled by the computer. It reads engine rpm and throttle position, trans temp,engine temps.



I would check the TPS (throttle position sensor). Sounds like it is off. This would delay the upsift. If you do not have a manual. check the voltage across the black and white wire if I remember right. At idle posiition it should be around . 75 to 1. 0 volt. ( I think my manual is at a friends house). If higher or lower you need to adjust the TPS. While you have the volt meter hooked up. As check to see if you have a steady voltage rise when you move the throttle threw the full travel.

 

[MSilva]

I just bought the 1992 last Friday. Have never worked on it at all.

Also, I thought a 1992 was all mechanical and did't have computer?

 

[Paychk]

92's have the computer (it is located behind the battery) the great thing is it plays a minor role in the operation of the engine. In fact the engine will run without it, your alternator wont work but the engine will run.



PS you would need to pull the fuel shut off solenoid plunger out and jump the starter motor.

 

[MSilva]

Thanks Guy's, I have a manual i will study it and try to fix

when time permits. If I can't fix it myself, I found someone that may be able to help me. Does anyone think it will do damage

to the transmission to keep driving it with these symptoms?

 

[Philip]

Does anyone think it will do damage

It will be all right. It is just a little annoying.

 

[banzaitoyota]

I drive mine like that

 

[MSilva]

Thats good news, the last thing I need is spend more money with Christmas around the corner.