Well just wonder if there is two different limp modes
Basiclly i just finished rebuilding the engine
before the rebuild i had it limit at 2500
after the rebuild it is now limiting at 4000 rpm
also before the problem that caused the rebuild everything worked fine.
Also i have to timing light time it also so that is probably causing some of the ruff ideal. Any ideas?

check your cam timing, you may also have a bad ecu or a bad sensor , what kinda car /engine/obd configuration are you running?

1992 240sx hatch with red top sr20det. Guess just the old school dignostic port.

hmm, consult port...iirc that engine has coil on plug ignition correct? is your maf hooked up right? could your ignitor chip be fried? also check connections with your sensors (crank angle, crank position , cam angle)

Ok update.
I did take the car for a short drive.
It ideals fine once it has warmed up
also it keeps the a/f ration at exactly what it should be in closed loop.
But soon as you try to boost a little it cuts out.
Also when i got back i sort of noticed/remembered that i forgot to hook the altinator at all so would that cause it to go into limp mode?

O btw i had to go back to school for the week so thats why i cant check it to see if that fixes it right now.

Hmm that could be it especially if ur pump and ecu aren't getting enough power. Make sure ur gauge cluster is hooked up and ur battery bulb isn't burnt