I recently swapped my 2.73 differential with a 3.42 in my 1999 automatic. I was under the impression that my hypertech programmer would reecalibrate the necessary issues after completing the gear ratio change portion of the programming. However, after completing the programming, the car stalls in 3rd gear during acceleration. I have gone back to stock settings and the car runs fine, but the speedo and odo are obviously off. Any suggestions???

 

...from my archives...

The Hypertech will do everything needed for rear axle ratio changes.... except for... the altering of the TCC Slip Table. And because of this, a C5 A4 with a non factory rear axle ratio will eventually set the P1870 error code and place the tranny into the limp mode.

The Hypertech has this "bug"... and as far as I know - it was never corrected.

more gear swap info here:

http://mikemercury.home.att.net/342.htm

 

Thanks for the quick reply!!

Do you recommend a particular programmer or might you be able to recommend somebody in the Western New York area to "finish" the job?

 

I'm not too sure about how far away this place is from you, but I've heard good things about them:

http://eastcoastsupercharging.com/Contact%20Us.html

I used to live in CT and had my 68 C3 vert at the time but that car didn't have all the electronic stuff that our C5s do.

Dave