this is pasted from another thread... thought it might get more response as new string.

i did a dyno pull that CLEARLY showed a big flat spot around 3500 or so... i know it's not the injectors, they're new... might be anti-knock??cuz of loud exhaust? never heard that one before... except that it goes away as quickly as it comes... i would post my dyno sheet but don't know how. lets just say... big drop around 3500 or so and then climbs right back up like nothing happened. only other symptom i know of is that the TPS wasn't adjusted properly at the time (WOT was 3.7V) and that when i've done a fuel pressure test, the pressure jumps up to 46 or wherever i have it set and then as soon as the pump stops running, it quickly falls to 20 something and stays there. new fuel pump in jan. (so i figure my regulator might be going bad or bad check valve according to the service manual, but isn't check valve part of the new fuel pump?) my buddy's factory car by comparison jumps to 44 and holds forever... car starts fine and runs well otherwise... except for the blow-by (i asume it's blow-by, haven't done leak down test) that i've got coming out of the dipstick tube... LOL car sounds like a junker now... any ideas of what might cause this big dead spot? i think i'll post this as a new string and see what we get.

 

ttt

 

What kind of mods? What chip you using?

 

just the mods in my sig... and the chip is a superchip.
got any ideas? i know i probably need a re-programmed chip to optimize perf.... but that probably doesn't explain the sudden drop and equally sudden return to normal...

 

Are you sure it just wasn't a hick-up in the dyno run? Do you have multiple pulls with the same results?

 

yep 3 runs... after the first run we thought maybe it was because of the oxygen sensor being disconnected for the air fuel ratio test (duh, dumb idea on a speed density car anyway) so we hooked it back up and still got the same results...

 

Do you still have your stock throttle body?

I dyno proved that a 52 does nothing on my car with cam and headers, with stock heads. This would mean that a 58 shouldn't do anything either. Some people have noticed low end torque problems with a 58 TB. Wouldn't hurt to try if you've still got it.

 

yeah, i've got it, but i've got a 383 coming soon, so that's why i bought the 58mm... just wanted to go ahead and use it...

 

...d'uh, okay...i feels reeel igorant