A4 Won't Upshift at WOT/ Backfiring
 

Last month I got 3.73 gears put in along with a tune from madz28 programed for harder shifts. Well the car was running fine until the other week. At first I noticed that when I floored it, it seemed to always start in 2nd gear and wouldnt downshift to 1st.

Then later on that day when I decided to floor it on the highway, once i hit the upper rpm's the tranny wouldnt upshift and the car would just backfire. But whenever I would drive it normally it would upshift just fine, even at half throttle or more.

So I drove it around a few more times without ever flooring it and it drove around just fine. Then the other nite I had to give it a lil gas to get by something and it kinda did the backfire thing again but not as bad because I didnt exactly go WOT. After driving a few more seconds down the road the engine started to backfire quite loudly just at random times.

After it did that a few times I put the car in neutral and coasted off to the side of the road, but while doing that the car just died on me. I was able to start it right up and drive home fine. So what im asking is if anyone has any possible ideas what it could be, whether it be from the gears or the new pcm or any other possible problems? Thanks

Mmhmm I dont want to scare yea, but your tranny could be dead. I would say toss your old tune in but, with 3.73's you wont properly up shift. Ion knows his shit so would be hesitent to think his tune is off, the values should be the same.

DO you have a shiftkit (trans go) and have him increase the line pressure, too much pressure doesnt allow upshifts. I had a big issue with the 3-4 WOT shift.

nah there is no shift kit as far as i know, just had the pcm programed for harder shifts

Id have him take that out and see if it allows proper up shifts. I mean from what you described its not allowing the upshift, the backfire is prob the rev limiter.