Quick background. Just installed new street ported s5 turbo motor to replace the one I blew last year. Car ran old motor for 5 years at over 400hp, everything worked well.

Running PFC, adjusted FPR a bit down to 40psi idle (from 44), just removed BAC valve, OMP, and blocked off coolant to Throttle body. Otherwise, turbo, piping, etc is all aftermarket.


Problem/Symptoms:
Car fires up fine and revs to 2000rpm on its own. Sounds smooth. After about 5 seconds its cuts out and tries to stall, I can catch it with throttle and hold it around 2500rpm for another 5 seconds or so but it will again cut out, even with the throttle still held at 2500. This cycle might continue a few times or it'll just drop too low and die.

The BAC was recently removed, but I always had the air input blocked off, so not sure if that's is the issue.

TPS was never touched.

Any thoughts? Anyone had a similar problem?

 

Fuel pump relay? Will it stay running with the pedal? Or die everytime?

 

Die even with the pedal down. It seems to be fine for 5 sec, then cut out for 2 sec. If it doesn't die in that 2 sec it lets me rev it back up for 5 sec again. Like a cycle, but it eventually dies after one or two times of doing this.

 

Try bypassing the pump relay, if the contacts are going bad it may be able to sustain a long enough connection for start up, but after a load starts to pass through the relay may fail. That's something I would try first.