Hard shifting, Check Engine???
Thread Starter
Instructor
Joined: Apr 2004
Posts: 145
Likes: 0
From: Sunny SoCal
Hard shifting, Check Engine???
2004 C5 Auto... Recently swapped 2.73 out and installed 3.42's also had a Predator tune. 1ST PROBLEM... At WOT the car cuts out and wont shift to next gear without backing off the accellerator. 2ND PROBLEM... Now on a steep freeway run uphill the check engine light came on. After exiting freeway the car shifts very hard. Park it and let it sit for several hours and the hard shifting stops, (check engine light still on). Tranny fluid temps were 198-205... Any ideas!!!??? Thanks 
Race Director
Joined: Aug 1999
Posts: 17,541
Likes: 2
From: Manhattan, KS Missing SoCal since 2005
I am just gonna guess at this, but it sounds like the torque management parameters are out of whack.
Might want to post this in the C5 Tech section for opinions from someone who knows more than me....
Might want to post this in the C5 Tech section for opinions from someone who knows more than me....
Race Director
Joined: Oct 2004
Posts: 10,719
Likes: 18
Predator install
After reading numerous accounts of problems associated with the Predator system installation, I see that apparently the Predator program really screws up the C-5 computerized system. I really do not see any advantage if it does not work as advertised. If the system is restored to stock, the problems seem to just go away. Is there a message there? JMHO.
Burning Brakes
Joined: Sep 2003
Posts: 1,230
Likes: 0
From: baton rouge la
Originally Posted by OBSESDD
2004 C5 Auto... Recently swapped 2.73 out and installed 3.42's also had a Predator tune. 1ST PROBLEM... At WOT the car cuts out and wont shift to next gear without backing off the accellerator. 2ND PROBLEM... Now on a steep freeway run uphill the check engine light came on. After exiting freeway the car shifts very hard. Park it and let it sit for several hours and the hard shifting stops, (check engine light still on). Tranny fluid temps were 198-205... Any ideas!!!??? Thanks
The first problem is , youre hitting your rev limiter.
The car is exceeding the designated rpm parameters, before changing gear.
Once you change from a 2.73, to a 3.42 rear end, all of this has to be adjusted properly.
The shift points are firmed up also...........perhaps too firm to your liking.
I have no clue about the check engine light.
Check the codes on your dic.
Le Mans Master
Joined: Dec 2003
Posts: 5,622
Likes: 0
From: Savannah Georgia
Cruise-In VIII Veteran
Did you install a Torque Converter. If yes then the computer is seeing to much slip and is sending a code that will cause the Check eng light and cause the hard shifting. You might want to PM Mike Mercury He can tell you anything you need to know about Gear swaping and the Predator programer Good Luck 
also you can clear the codes to get you by for now
also you can clear the codes to get you by for now
