greenmachinedriver

well after a year of collecting parts and pices i finally go my new engine all together today. 383 w/forged eagle rotating assy, 4 bolt main conversion,all done locally at Exteem horsepower. le2 heads, le3 cam, comp nsa valetrain. started right up on the first turn of the key!
i had the pcm tuned by pcm for less, but i think i may have made a mistake when i told them i had 36lb fast injectors. the injectors i have are off an ls1 so they are prbably not rated 36lb at lt1 fuel pressure. i got an areomotive adjustable fpr so i set the furl pressure to 55 psi to be closer to ls1 pressure. what do you guys think? the tune seems decent but idle is a little unstable. no black smoke or gas smell so im pretty shure its not rich.
also the fuel pressure falls off to zero in about a minute after shutting off the engine. and when the engine is reved the pressure drops slightly. iseem to remember its supposed to increase slightly.
on a side note i put on a tsp rumbler exhaust and it is loud! it is barley quieter than open headders.

Formula408

My fp drops slightly when hitting the throttle with no load, but under a load goes up a few psi. I assume when you rev the engine with no load and immediately let off the throttle you end up creating more vacuum momentarily with the engine up in rpms pulling against a closed throttle which causes the drop in fuel pressure.

As for the leak down, that seems kind of fast to me, mine goes up after shutting off if the engine is warm and holds pressure a long time, sounds like something is leaking to me...

mrmint69

I think the areomotive adjustable fpr will loose pressure much quicker than stock ones.

greenmachinedriver

to formula 408 that makes sense because when i ppinch the vacum line the pressure does go up i just was not thinking it all the way through. i do plan on getting a dyno tune shortly. other than a little extended cranking what could the fuel pressure droping problem hurt.