I have a 2000 Silverado 2500 142k miles with the 4L80 4wd and I've done all the services (dex6) but once it's warmed up a little (150* trans temps) and after I romp on it, it will constantly bang every gear. Harsh engagement regardless of throttle position. I've heard that there's an issue with the shift pressure spool valve ovaling or eroding the bore in the valve body or something to that extent. So the spool valve will bypass or stick. It feels like it does because if I shut the truck off and go into a store and come back it'll be back to normal.

I don't feel like dropping the valve body but I may have to. Any cheaper or affordable replacements out there? Ideas? Is it that risky to drop the valve body and not losing any check *****? Or not that bad?

 

Have it scanned for codes, There are several codes that can force full line pressure.

 

Ok. It did this before I loaded a tow tune too. It shifts better now when it's acting right but still bangs randomly once it's warmed up.

 

Of course it hasn't been doing it lately. I fixed an exhaust leak that I've been dealing with since I put the truck together. Was a #1 cyl primary exhaust gasket leak. Looks like the cheap gasket blew out. I put a GM gasket in. It's nice and quiet now and coincidentally the banging has stopped.

I had a bunch of codes. One for EGR which I deleted and turned the MIL off, I should set it for no error reported.
One for HO2 B1S2 for some reason.
A coolant temp sensor code for the sensor that the plastic finally broke. I superglued it back on. It broke during reassembly but was barely hanging on. I guess I nicked it when I was doing the gasket. Still works.
One for No MIL

So P0118
P0141
P0405
And MIL OFF. I had one that just said "sensor" but no P prefix.

 

Yep. Still doing it. Wasn't even warmed up (~125*) this morning and it started banging gears.

 

Stored DTC's somethings making it default causing the problem. Check the freeze frame

 

Whatever happened with this? Get it resolved? If you don't have any codes and with that kinda milage, try a new epc solenoid. Don't have to drop the valve body and you can do the job for less than $100.

 

Haven't been driving it. It blew a brake line and I'm waiting for a whole vehicle pre-bent kit to come in. I have I have to re do the whole rear channel to get it drivable again. Single rear line (3ch ABS)to the left and right sides all the Way to the calipers. Everything is so rusted nothing will come apart.


I'll have to run a datalog when I get it on the road again. Thankfully I have a backup car.