I'm Thinking about putting 3.42 gears in my 95 z28. I currently have 2.73's. My friend was saying that I might have to re-tune my computer after but he wasn't sure for a 95. I was wondering if anyone knows what I'll have to do? Also if i do, Can i just reprogram it through the port under the dash that's under the dash off his laptop that's used to read codes or do i have to do something different. Thanks for the help, Justin

 

I programmed in my 4.10 ratio with the Hypertech Power Programmer. Takes a few minutes but is a bit expensive. Hopefully you can use an editor to program your ecm with a laptop.

 

Yea, I really don't want to get into getting a programmer. Also what's a good set of gears to get? I was looking at Richmond.

 

There are several reliable sources for low-cost mail order tunes for the LT1 PCM. They don't charge a lot for simple changes like the rear axle ratio. But... since even a stock engine will benefit from a good PCM tune, think about getting more than the gear ratio reprogrammed.

If you don't reprogram, your speedo will read 25% higher than actual speed, your odometer will add on 25% extra miles as you drive, and the shift tables for your 4L60E transmission will be thrown off, since they are based on vehicle speed.

 

Well my engine is stock right now. I wouldn't mind having it tuned but i just don't have the money plus i would like to wait until i have a intake,exhaust and so on and have it all done at once. This would be cheap for me cause my friend would do it for nothing and has the fluid to put back in for me. But I'm still wondering if it's possible to adjust the PCM through the port under the dash? Thanks for the replies, Justin

 

Yes, in 94-97 with the fixed-chip PCM's, you connect to the ALDL connector under the dash to tune the PCM. To change the gear ratio in the PCM, you could use a Hypertech programmer, software like LT1_Edit or TunerCats, or get a mail order tune. They can send you a tune that you upload to the PCM via the ALDL connector, or you can send them the whole PCM.

You need tuning software, as mentioned above. You can't "tune" with scanning software.