I have a 2008 Silverado 5.3 with a TVS 1900 Maggie, FLT Level 7 trans, Yank SC3000 Converter, ARH Headers, ....

The truck ran good, once I put the new trans in with the yank the truck has ran REALLY poor at about 52% throttle. I have taken it to the tune shop twice and for the life of them can not figure it out. If feels like it is shutting down cylinders then once you get past it and it down shifts it pulls strong again. Tourque managment is all been through we are running out of ideas and the truck is no fun to drive. The more load it is under the worse it gets! Pulling a trailer forget about it. The more power or boost the worse it gets. PLEASE HELP ANY IDEAS??

 

Well, tell us about the logs that were ran. Was there a significant amount of timing pulled (KR) during those events?

 

When this first started happening it was pull 10 deg of timing between 52% and 58% then pulls great. Yesterday they did not say it was pulling timing but one of the O2 sensors was dropping off and the other was sweeping back and forth out of control. When the truck looses power it comes up with a "trans input sensor fault" then he put the stock tune in and it was throwing a "lost communication with fuel pump modual" fault. I don't know alot about tuning but I do know my high dollar truck runs like crap!

 

Sounds like an input (sensor) issue and may or may not be a tuning issue.

 

did you tune for the converter so that it locks/unlocks properly. Could be locking/unlocking and causing false knock?

Just a guess

 

Makes me wonder if a harness is pinched.

 

Do these sensors go bad?

 

I was thinking the same thing. I looked that truck all over and see nothing out of the norm. I am going to pull the trans pan to look at the input sensor to see if it is loose or unpluged.

 

It has been tuned for that and even the knock sensors turned off for one run to see if it was picking up a false knock and still the same thing.

 

The earlier post regarding a pinched harness made me think of a harness being pinched at the bellhousing/engine interface vice under the tranny pan.

Answering another of your questions, all sensors can fail.

May just be a bad ground somewhere.