I am new to the forums but this is
A really big problem with my truck I've had it for almost a year it's a 1994 chevy k3500 Cheyenne 6.5td I've basically have changed pretty much almost everything that could cause this problem it has done this since day 1. I have just recently put a new built trans it it last week with new torque converter new heads pmd relocation new ops new CD-R valve new app sensor HO Bosch injectors and still continues to either slip over 70 or not go over 70 and when I does it goes into limp mode is there any other sensors that could be doing this as in the optical sensor ecm coolent temp sensor. need help asap. And also the torque converter does lockup over 55

 

you might have a problem with the transmission control unit. Its located behind the glove box if i remember right. 94 has that and the temp sensors control limp mode they must read the same.

 

ohm out the coolant temp sensor its a on and off sensor. the other one on the front right cylinder is the gauge in the instrument cluster

 

also tyhe throttle position sensor may be out of adjustment. hope that helps

 

Thanks guys I'm bringing it to my transmission mechanic tomorrow so he can check out everything I'm going to change the temp sensor for the Ecu also I've noticed it has a problem getting out of warm up mode recently it's a fairly new temp sensor because I changed the heads but New doesn't mean good.

 

94's transmsiion shifting def used that sensor. sounds like a good call.

 

I changed the Ecm coolant sensor with a new pig tail took it on the highway and got to 75 then it just fell on its face and started slipping but no limp mode I just don't understand what's making a brand new transmission slip like that could it be a wrong or bad ecm this problem is haunting me .

 

Did you happen to flush the lines when you changed transmissions?

 

Yes I flushed the whole trans cooler system

 

Sorry I had to ask I've seen several people do,exactly this and wonder why their new transmission is slipping after just a few miles,I probably lean to over kill just had to have a 4L60E rebuilt a couple months ago ago and I used 3 cans of flush and between the can used compressed air to force out all contaminants.

Maybe the person who rebuilt the transmission missed something as you know to er is human.