I recently put in a engine in a bank repo I bought. A 3800 ,vin k. When you fully accelerate to the floor,the engine will not even make it to 3000 RPM before upshifting. Also cruising at 60 ,if I accelerate to the floor it will not downshift. Not being able to drive it with the bad motor,I do not know if it was like that before or if it was something we did. Any ideas ?

Could this be the TPS not showing throttle positions above 60%? Can you get a scan to see what your PCM is seeing?

I loaned my scan tool out a while back and was returned broken so I am unable to. The fluid is clean,red and not burnt. The transmission works fine if manually shifted.I will probaly have to find a scan tool to see what is going on.

you can check the tps VERY easyily with a $10 digital multimeter walmart even has em.


its a piece of cake to check even with the car off

You might also check any linkage between the throttle body and tranny, for binding or looseness.

I would check the TV cable before the TPS... I remember when my TPS was bad, that my car still shifted normally, only the idle was higher.

good point, something may have got yanked when the engine was being swapped.

The TV cable isn't on all cars guys. Please think about the driveline you are discussing.

The 4T60 and 4T65 would be the models of transmission being discussed by this poster, not the TH440

Some things to look into.
Gear ratio
Was the trans from the same year

While some yards show them as compabile in certain cases we have found crossing years/gear ratios to cause silimar issues.

Finally got my hands on a scan tool. It came up with 3 codes 112,122,123. First one is IAT. Next 2 are for the TPS. Do you think either would have anything to do with the shifting problem. Occasionally it will idle suddenly to about 2500 rpms and then it will slowly go back to normal also it will occasionally fall flat on its face ,have no power, and a few seconds later it would be fine again.

Connect the IAT. You probably left it undone.

Replace the TPS or make sure it'* installed correctly.