Under heavy acceleration my Vette will not shift from first to second. Weeks have been spent trying to identify the issue and cause of the problem. We have noticed when driving it on the street the speedometer seems to work just fine, but under heavy acceleration the speedometer reads
"0" until the Vette is moving at about 15 MPH and then the speedometer starts working but starts indicating the spped at 1 MPH instead of the 15 MPH that the Vette is actually traveling.
What I know about the Vette's Speed Sensor I could write on the head of a neddle - could a faulty Speed Sensor cause the computer to send a late message to the transmission to shift and allow the engine RPM to advance high enough to hit the Re-Limiter?

 

It could if you have a late C4 or later Corvette with an "E" transmission. Not at all in the C1, C2, or C3, cars.

RACE ON!!!

 

Hey Bill,

Did you change the PCM and put the stock one back in or take the programming out of the PCM that is presently in the car and return the tune to the stock tune. We talked about that at the last Challenge.

 

I still think it in the trans.

 

Bob - We replaced the PCM and have reprogrammed it creating 350 RPM differences between all shift points and the rev-limiter which is now programmed at 6000. We have now also replaced the Speed Sensor plus the trans electronics.
John - I just can not see how it is the transmission, it has been gone through now four times - twice completely apart. Every part in the damn thing is NEW - we have even changed all the supporting electronics - I think the only thing that is not new on the Corvette at this point are the DOOR PANELS - I know my check book thinks I have bought two new Corvettes!!
I get the Vette back tomorrow from the shop and we will take a couple of practice runs down a side street just to make sure all is looking good but I can't get to the drag strip until the12th at E-Town for the Corvette Challenge event. I really don't know what I will do if the thing isn't right. I'm really disappointed since prior to this I had the Vette running down in the 12.4's and I think that is pretty good for LT1 with no more that a Hot LT4 cam and headers. I even had a couple of 1.69 60's on the old BFG DR's - now it has been 14 out of the last 15 passes that the Vette has refused to shift. If its not right after all this I think it maybe heading to someone else's garage to find a home. We'll see.

 

Bill, Don't give up just yet.. I'm sure it will get fixed... Sorry I can't get out with you this weekend..

Good luck and keep us posted..

Ernie

 

Bill,

I sent you a PM.

 

Bill,
I sent you a PM.
Rick