Death on sudden opening of throttle

[Roger Heflin]

> 
> I've finally rebuilt my intake system (welded up from steel exhaust 
> tubing), but I've got the following problem:
> 
> When the throttle is mashed at lowish RPMs i.e. <2000RPM
> the engine dies for about 1/2 - 1 second, before getting its
> act together and then pulling strongly. 
> 
> Sounds like not enough throttle enrichment you say... Not so, 
> I've tried enough enrichment to sink a battle ship, and no
> noticeable difference (just get lots of black smoke). I've tried 
> from no enrichment, way upto pegging the injectors at 16ms per 
> injector per cycle (100% VE requires only about 7ms)
>

Too much throttle enrichyment will also cause that.  I was running
my car with 30lb injectors with the stock computer think they where
22lb injectors.  It ran about like you describe, when you hit the
gas it would stall out for 1/2 to 1 second and go like a bat out
of hell.  I have since reprogrammed the computer to know it has
30 lb injectors and it is much better.   Mine was running very very
rich.  If you have O2 readings you might check them.  I think mine
was so  rich that there was enough fuel to cause things to not
burn very good.l


> My setup has a second set of injectors mounted on the runners,
> if I switch to use these a the primaries the problem gets much 
> worse. This indicates to me its something like fuel dropping out 
> of suspension.
> 
> Changing the injection timing (Sequential system) does help a little, 
> but not much.
> 
> FYI: I've got a reasonably small cam in it : 255deg @ .006", 40 deg 
> overlap.
> 
> FYI: I sample the revs & MAP sensors 16 times a second, so its not an 
> ECU response problem.
> 
> Q. Whats happening here? Theories anyone?
> 
> Q. Do other people here have this problem? Whats the solution?
> 
> Cheers.

On mine there was so much fuel I am pretty sure the fuel was dropping
out of suspension, and inhibiting the burning of the fuel significantly.
Also this was at large throttel openings, enough that the car was very likely
in WOT mode and running from the prom, and not with the idle enrichment
type settings.  I leaned things out quite a bit and things are now much better.


				Roger Heflin
				rah at horizon.hit.net