Rebuilt Transmission - Poor Shifts

[cpayne5]

Not a question, but hopefully some info that may help others.

I pulled (two weekends ago) and reinstalled (this past weekend) a buddy's 4L65E on his '03 Denali. Upon reinstall, it was shifting poorly. It was flaring between shifts and the shifts were slow and soft. He was very worried that we were going to have to take it back to the shop that did the rebuild. I was hopeful that we could resolve the issue and pressed on.

Did some digging and found that the MAF can cause these symptoms. Unplugged the MAF and boom, solid shifts (albeit in some sort of limp mode). I cleaned the MAF this afternoon and all is well.

It has 204k miles on it, and I'm sure it had never been cleaned.

Hopefully this helps someone down the road when trying to debug something similar.

[68C15]

go easy on it while learning shift points, line pressures and all. I'd hate to see you blow the sun gear off the reaction carrier