408-99-f

My forged iron 408 is hesitating under load intermittently. tfs215 heads, fast 90/90, 247/251 624. 42lbs injectors. No air, egr. Its not maf, map, coils, plugs, wires, o2, tps, iat, I have either unplugged or swapped. I'm prob close to the limits of my stock fuel system, car ran great for 4000 mi. Now will hesitate at aprox 50% throttle in fourth gear. Or similar load conditions. Fuel pressure is at aprox 55psi when this happens. But pressure drops to about 52 while wot with no hesitation. Any help would be great. Has anyone seen a crank sensor do this? Also has new fuel filter

408-99-f

Pulling the valve covers today to check for a broken valve spring. Doesnt feel like this but I'm out of ideas

408-99-f

Not a broken valve spring. Going to do a crank relearn. Will it run off the cam sensor if I unplugged the crank to try and rule it out??? Anyone

2xLS1

iTrader: (25)

No. And doing a crank relearn is only for misfire detection. I doubt you have misfire detection enabled with a cam that big. And no one is going to be able to help you without looking at the tune and a data log when it is doing it.

408-99-f

Ok, makes sense. I have gone over lots of live data. And reviewed data logged. And yes my misfire is out. I understand having another set of eyes on it may pick something up. I'm having trouble loading my data log, as its not hp, its just logged on a otc genesis. I'm working on it. Now in the meantime, is there any outher suggestions as far as sensors, or anything mechanical I have not listed that may cause this??? Now I have seen a reflashed pcm that was swapped into a truck cause a hesitation,(his would do it in park, unlike mine) and did a crank relearn and it fixed it. Might have been coincidence, but was suggested by a gm dealer tec. All I know is it worked. He said if its a new flash and there is no relearn done. In rare cases this can happen???