hello everyone, I was just wondering if someone can help me with my car? I have a 1991 Z28 with a 305 TPI and the 700 auto with OD. The car originally had 2:73 gears wich we just changed to 3:73! The speedometer is way out of wack now. I now a guy who can fix that but my question is why is my car cutting out at about 105 m/ph? It wouldn't be so bad if I was actually going that fast, since my car won't reach that in the 1/4 mile anyway. But I'm not going that fast! I guess my question is, do I just fix the speedo and live with it, or is there a way to bypass that situation altogether? and what is causing this? If anyone can help I would appreciate it, big time! thank-you!

 

that used to happen to me, when i went from 2.73's to 3.42's. my gauge would read 110 and stop me, but i was only goin like 85. if u fix the speedo it will solve your problem

 

The problem is in the ECM (computer). It is prorgrammed with a top speed. With the gear change your hitting that top speed much sooner but the computer still believes that your at 110 and its time to shut you down. Change the speedometer gear in the transmission to fix the speedometer. Later if you want to do away with the top speed limit in the ECM you will have to change the chip.

Steve