DeTomaso Mailing List: April 2000, Message #235

I'm still messing with my Haltech system after more than two months, 
but as of this afternoon, I think I'm as close as I can get without 
getting back on the track again or, better yet, on a dyno. I'm 
working on getting to a dyno and my son has a connection that I hope 
will get me in one day soon... Ever tried to get on a dyno in the 
spring? It's racin' season, dudes! Everybody's dyno is booked solid 
for weeks! Or at least that's the case here in Houston.

I spent a good half hour accelerating up and down a deserted street 
here this afternoon. From about 1500rpm up to 7000rpm in 2nd gear 
while taking quick glances at the O2 sensor. The few folks that did 
drive by thought I was obviously nuts...
I'd seen 'fat' place and lean places previously, so I was using this 
session to fill in the lean places at wide open throttle. I was 
amazed at how much I had to increase the injector time from around 
4000 to 6000rpm... And then it sort of levelled out.

Anyway, the question...

I had just figured that the response of the engine should be linear. 
i.e., for a given rpm range, the amount of time the injectors spend 
open should increase linearly. Methinks I'm simplifying it too 
much... Or full of shit... or whatever.

Just based on the fuel/air meter, 'seat of the pants' and the SWAG 
factor, I find that it's not linear at all. Or else the O2 sensor 
can't handle the higher rpms? Or something I'm not considering like 
the cam response and all that good stuff.

What do all you EFI experts have to say on the subject?

What kind of curve would you expect when you plot rpm vs. injector 
milliseconds at wide open throttle?

Thanks,

Kirby


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Kirby Schrader                   schrader@ev1.net

'71 Pantera #1661
'78 Longchamp GTS #3001  (It's for sale! Contact me if interested)
'96 Mustang GT  The wife's
http://users.ev1.net/~schrader/