I dropped a new tranny in my car. Everything seems fine except when I brake and then let off the pedal it revs up. I checked the vacuum hoses I could see and they looked fine. Anyone got any suggestion?

 

I would not really have any suggestion there, Vaccume would be a first check. I would also check for and pinched or broken wires and over the entire installation. Now if the converter has changed stall that could affect it also.

But do you actually mean by chance if you brake and let off the petal while driving the rpm jumps up then comes back down when you are at a steady throttle maybe ?

 

It doesnt go back down when I press the gas. It jumps up about 400 rpm when I let off the brake an its an instant jump.

 

I would not know where to steer you there, You will need to look at the data from PCM to see why thats occuring

 

Its not throwing any codes. I drove it yesterday and its only doing over 30mph. That just makes it more confusing.

 

Sounds like the converter clutch releasing and then applying. Good luck with the new trans. Vince

 

Is it going to mess anything up if I leave it like that?

 

Anybody got any suggestions?

 

The converter unlocking would happen when you applied the brake not when you let off the brake.

 

Yes its doing it when I let off the brake not when I apply the brake.

 

I am thinking some sort of idle surge related to vaccume but its hard to say. I would suggest you have it looked at by a garage.

 

I tried finding vacuum diagram but couldnt find anything. I'm going to put it back on the lift this weekend and double check everything make sure nothing came loose before I take it to a shop.