Ok, here is what is happening. I have a 2001 7.3 with 83,000 miles on it. Yesterday I was heading home when I pulled off from a stop sign. The truck shifted normal from 1st to 2nd. When changing from 2nd to 3rd (auto trans) when it shifted to 3rd it felt like an engine brake was activated. I drove for a bout 1 mile, pulled over looked under the truck & checked the fluid level. All normal. got back in the truck and the same thing happened again. I could slow down (below 20mph) and it would downshift to 2nd and all was normal. Speed up to where it would shift to 3rd and bog again as if an engine brake was engaged. I can manually shift the truck to 2nd and run 40+ until I shift back to "D" on the column. I removed the T&S chip HOPING that would be the issue. But it was doing the same thing when shifting 2nd to 3rd. The RPMs of the engine do not go up but I can accelerate and I still lose speed and it feels like the "brake" is applied stronger. Any ideas as to what might be going on. I am the 3rd owner of the truck and I have had it since 53k miles. Never had an issue like this before. Also had a mechanic friend of mine rode with me and he has never seen anything like this either. He agrees that it seems like an engine brake/exhaust brake is activated. Any advice would be greatly appreciated.

 

@Mark Kovalsky Probably has some ideas, he seems to know these transmissions pretty well.

 

Never heard of that, like to see what Mark says. But did it smoke when this happen? That would lead it to the EBPV for sure.

 

The Exhaust Backpressure Valve (EBPV) is my guess. I can't think of a way the transmission could do this.

 

Sticking caliper slide pins?

 

That only stick after the 2-3 shift? Seems farfetched to me.

The EBPV is electronically controlled. It's possible that there is some cross feeding of power that is enabling the EBPV when the 2-3 shift is commanded.

 

Missed that part Mike

 

Who's Mike?

 

You know...Mike, the Mark transmission guru

 

Lololololol Sorry Mark.

 

Wire the EBPV open and try again, the easy way to test it..

I think mine fell off...

 

Thanks for the replies. I am thinking it will be the EBVP from what y'all are describing. I now just need to find it on my truck. I will try to take a video of what it is doing before I fool with the EBPV.

Sincerely

Dale G

PS. I will let y'all know what the verdict is. Again, thanks so much for any advice.

 

Good luck Dale, hope we helped!

 

He's describing a time about when the TCLU occurs. Still nothing possible there?

 

I hope you can tell something about the video