I've read numerous issues about tachs jumping around, but my issue isn't the tach jumping around during idle or just for no reason, its after vtec right at about 6.8k the tach shoots back to 0 until the rpms drop down. Anyone else had this issue? I've seen alot of people state its the dizzy but this issue doesn't seem to be like most tach problems . BTW: LS cluster wired into a ej8 w/ a jdm obd1 b16 and obd2 01' gsr dizzy wired to work.. any input would be great.

 

bump for some help, checked my trans ground and ground on thermo...

 

Test your vss? vehicle speed sensor

 

I am having the same problem. I have a 2000 ls i put a gsr head on it. the shop I took the car to screwed up my stock block and they put in a b18a block. anyway i have a step down jumper harness from obd2b to obd1 and right at 6k the rpm gauge jumps back down to zero until rpms come down under 6k. i tried getting a new harness but i still have problem. when i remove jumper harness and connect stock ls ecu gauge works fine. problem only happens when in vtec. other than that car runs fine.

 

Dam I have the exact same problem, I suspect the vss but my speedo still works and also I have noticed my odometer and trip do not work any more