just got my gsr started, it is its first ever startup and i put a p28 stock ecu obd1.. it idle normal for maby 5 seconds and jumps continuously from 500-1800 rpm...

whats going on?
also wont let me rev up the engine at all it will shut off.

 

Idle - You're running a GSR on a stock P28.

 

I doubt the idle issue you have has to do with running a stock p28, however you shouldn't run a stock p28 on a gsr motor...

Are you throwing any codes ?
Check your malfunction indication codes if you are throwing any & get back to us.

If you have a fast idle thermo valve, rebuild it...

 

lol @ wonky


I'd check for vacuum leaks too, the GSR intake hides vacuum ports and lines