I have a 94z with 115,000 miles. I have the basic bolt ons(kn intake, headers, etc) but not long ago, I installed a 52 mm TB, reusing gaskets. After I did this, my tranny was shifting soft, and early(also lagged a little). I thought the computer might adjust after 100 miles or so, but after about a month, I couldnt stand it any more, and took it off. I replaced my stock 48mm, reusing gaskets, and everything went back to normal, which I like.I searched for information regarding this subjust, and have found very little information on it. Ive read up on a couple of possible answers,(Tps, vacuum leak, tranny line pressure) but im not sure what the problem actully is. I dont know all of the factors on a throttle body that could effect the transmission shiftpoints. I bought the throttle body from a guy on ebay, rebuilt and ported. The throttle body looks good. Someone please help

 

The line pressure needs to be raised when using a 52mm or 58mm TB with an A4. The TPS is instrumental in determining shift firmness. For instance with the 52 the PCM is seeing less throttle opening than a 48 for the same amount of air that is being used, therefore it will shift softer. This can be corrected by one of our resident tuners.

 

Thanks for the info anaik. I have been wanting to get my car dyno tuned. would I be able to correct this problem with a dynotune, or would you recommend something else?

 

The tuner should be able to bump the pressure up. If he can't get another tuner.