[Fast305]

Originally Posted by ImpalaGuy

So that's old news, now for the new news...

Right now the truck runs fine in general driving or WOT but still has two issues:
Hesitation. Pretty bad when I smash over 50% throttle from idle. Sometimes it dies. I've combed the intake and TBI for vacuum leaks and haven't found anything wrong mechanically.
Poor running in open loop. It spits and misses and pops. Once it hits closed loop (3-4 minutes) it clears up almost instantly.

I think both of these are the tune, but I can't complain about Brian at TBI Chips since he's been very responsive. In fact he's sent me SEVENTEEN TUNES so far trying to work these things out. Sometimes even two a day. And the first 6 or 8 was chasing the stupid coil problem above and the fact that the xtreme-fi adjustable fuel pressure regulator won't go below 17psi.

The good news is that I put in a new fuel pump (Walpro 190l/hr) and at WOT it runs GREAT. Yank's Truck Thruster 2600 stall converator stalls around 3000 behind the 383, so the engine really jumps into its power band. I'm anxious to get it to the strip this spring.

So that's the scoop. I'll keep in touch.

Why are you worried about going below 17 psi? Assuming you stll have the stock 61 lb/hr 350 injectors, you should be worried about getting it up around 25 psi and tuning it from there.

The hesitation is lack of tuning in the AE department as well as the increased throttle body size and plenum volume in your intake. The requirements are drastically different from the stock sized TBI and the tiny heated plenum of the stock intake. I bet DE is just as bad with possible surging on deceleration.

Idling poorly in open loop is a sign that the VE tables or the timing is off.