I have a 97 z28 with LT1 engine .Car has only 59K miles on it,
The problem making me nuts is transmission it kicks from 1st gear to 2nd however rest of them shifts very smooth from park to rear is normal no hitting or kicking and 2nd 3rd and 4th are ok, but when I take off from the red light it goes around 2000rpm and shifts very rough and kicks a little, by the way odometer shows wrong when it shows 50mph actually other vehicles around me are going around 65, when i unplug the speedo sensor it does not shift at all I put it in the first it takes off but when it time to shift it does notm, It stucks at the first gear, I flushed it, no change, torque converter has been replaced with a new and it didnt do anything neither, Do you have any idea what could that be When I purchased the vehicle there was lots of performance parts I pulled them all out, and I saw few cables were cut on top of the transmission and they were put back together very amateur do you think this is causing that or transmission is gone already?
or maybe the driveshaft? or differential? any help will be appreicated since I sold the vehicle on ebay already and owner will be picking it up this saturday.

 

since it had a lot of performance parts, (why did you take them off? ) But the PCM could have been reprogrammed for those parts, and the shift points could have been changed. Might not be a tranny problem, might just be the computer.

Just my thoughts, I may be wrong

 

I had to take them off as the vehicle for sale and engine light was on, but now its on again since there is no catalyst, how do you think I can find that out? if the shifting points are changed or not, do you think buying a new computer box will solve the problem?

 

Your local dealership should be able to refresh your PCM back to stock, or at least check out what's wrong with it.

Also I think AutoZone will scan the car for free, giving you all the SES codes that come up, but that's not a fix, only a way of checking.

 

I will try them lets see whats going to come up, basically you are thinking that it has something to do with pcm, not the trany or speed sensor?

 

Yeah that's what I would guess first.