[urq] EFI + MAC-14 maxing ataround 5k RPM

Cody Forbes cody at 5000tq.com
Wed Oct 24 17:20:05 PDT 2007

> IIRC Cody, the older EFI designed systems defined Alpha-N for the
> changeover from MAP to TPS to accomodate big lumpy cams, ala race
> car, because the MAP signal was unstable.  The newer EFI systems use
> MAP/TPS/RPM 3D tables for tip in transient response and fueling.  As
> I haven't had the pleasure of playing extensively with MS, I will
> assume it uses the standard MAP v RPM tabling you describe.  Unless
> Ben is running a 272 cam, this shouldn't be an Alpha-N type problem. 

What you refer to is known usually as 'Hybrid Alpha-N' which was pioneered on the F40 IIRC. MS can be run in speed desnity mode, MAF mode, alpha-n mode and hybrid alpha-n mode, but most run speed density with only a very small handfull on either form of alpha-n. Anyways, yeah Bens setup is on MAP vs RPM with modifiers like air temp, coolant temp, TPS accel enrichment (like a carburettor accel pump).

> Not having the same tables to stare at, I'd take a swag that the
> injector DC should be 50% or less with 'just' a run to 5k without
> load.  Maybe I misread what Ben put forth, but I swear I saw 100% DC
> mentioned.   

He did say that, but was speaking out of context.

I just looked at a log file where Ben started the engine and slowly let it run up to 5k. Duty cycle is perfectly fine, never higher then 50%. 

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