Auto Transmission Question
Thread Starter
Advanced
Joined: Nov 2007
Posts: 93
Likes: 0
From: Carolina Beach NC
Auto Transmission Question
I have been driving my '90 Coupe for a little over two years now. To the best of my knowledge, it's all stock (L98 Auto). On a recent trip, I noticed on the GPS that the speedo is not accurate (GPS reads 70 ... speedo reads 60). Now, that means while I am driving in local traffic here in Southeastern NC (which can be a real PITA), the Vette won't shift into high gear until the speedo reads about 41 MPH which in reality is probably approaching 50, and the OD won't kick in until the speedo reads 44 MPH (about 53 MPH). That's on a normal, average start ... say from a traffic light. It's been that way since I bought the Vette. A while back, I had some work done on the buggy, and the mechanic told me that there's an aftermarket chip in the car. I did not know that. Would the chip affect the speedo reading and transmission shift patterns or are my actual speed and shifts normal? Can the speedo be recalibrated and if so, would that change when the tranny shifts? How can I tell if it's an aftermarket chip? What's it take to return to the stock chip? Would that make a difference?
I really don't mind it too much, particularly on a trip. But tooling around town, it's like I am waiting and waiting and waiting for the car to upshift.
I really don't mind it too much, particularly on a trip. But tooling around town, it's like I am waiting and waiting and waiting for the car to upshift.
Pro
Joined: Apr 2000
Posts: 696
Likes: 18
From: Jenkintown PA
I have been driving my '90 Coupe for a little over two years now. To the best of my knowledge, it's all stock (L98 Auto). On a recent trip, I noticed on the GPS that the speedo is not accurate (GPS reads 70 ... speedo reads 60). Now, that means while I am driving in local traffic here in Southeastern NC (which can be a real PITA), the Vette won't shift into high gear until the speedo reads about 41 MPH which in reality is probably approaching 50, and the OD won't kick in until the speedo reads 44 MPH (about 53 MPH). That's on a normal, average start ... say from a traffic light. It's been that way since I bought the Vette. A while back, I had some work done on the buggy, and the mechanic told me that there's an aftermarket chip in the car. I did not know that. Would the chip affect the speedo reading and transmission shift patterns or are my actual speed and shifts normal? Can the speedo be recalibrated and if so, would that change when the tranny shifts? How can I tell if it's an aftermarket chip? What's it take to return to the stock chip? Would that make a difference?
I really don't mind it too much, particularly on a trip. But tooling around town, it's like I am waiting and waiting and waiting for the car to upshift.
I really don't mind it too much, particularly on a trip. But tooling around town, it's like I am waiting and waiting and waiting for the car to upshift.
Open up the ECM coverplate where the prom is located and if a Hypertech (now there are many chips out there) it probably a piggyback design that mates to your stock prom. And if a piggyback design you should be able to read "Hypertech and part # after removing the coverplate. IF a Hypertech and piggyback design you can remove the stock chip and reinstall after removing from the ECM. Now, my ECM is located in engine department right to the left and over the battery, not sure if yours is the same. I do have a efile of the installation instructions for the Hypertech chip if you would like a copy. If so PM me your email address and I will send posthaste.
Good Luck and
SAVE THE WAVE
