[Diy_efi] idle control strategy for SD systems w/o bypass air control?

[Tom Sharpe]

BobD, Edelbrock has a new chip that sets the air temp to 55 at tps < 14 
which stops the blower roll by richening idle a bunch.  Maybe the code 
changed as well.  TomS
On Tue, 27 Aug 2002 11:28:13 -0500, pjr at teknology.net wrote :

> I had the same difficulty controlling a random, 100 RPM idle roll with a
> BDS blown, 355 SBC equipped w/ Accel DFI and 16, 25lb. injectors in the 
hat
> at 40 PSI F/P. I found that giving the engine as much idle spark as it
> would tolerate and then dialing back the fuel and spark alternately, gave
> me a pretty stable idle w/ only a random 25 RPM roll now. Kinda tuff
> controlling fuel on one of those monkeys.......long distance from injector
> tip to intake valve, large plenum volume, huge valve overlap and spinning
> rotors in the way....etc!   ;-)
> 
> 
> Cheers!
> PJR
> ----------------------------------------
> ----- Original Message -----
> From: <socrace at ameritech.net>
> To: <diy_efi at diy-efi.org>
> Sent: Tuesday, August 27, 2002 12:02 AM
> Subject: Re: [Diy_efi] idle control strategy for SD systems w/o bypass air
> control?
> 
> 
> >     There's another method that I've been using for awhile that
> stabilizes
> > idle rpm pretty well with or without an air motor.
> >     The method can be simply stated as follows: as idle rpm drops, 
richen
> > the mixture in direct proportion to the rpm drop. As rpm rises, lean the
> > mixture by the same rule.
> >     This works because an idling motor is (usually) pulling air at Mach 
1
> > through the throttle system. This means that air mass entering the
> manifold
> > per unit of time cannot change, so the mixture changes with rpm.
> >     I believe this is the main reason that an idling engine will stall 
so
> > easily with a sudden load change, as the rpm drops it just runs leaner
> and
> > leaner.
> >     I used this method to stabilize the idle on my Edelbrock Pro-Flo, a
> > typical heat soak "blower roll" idler.
> > Bob D
> >
> > On Mon, 26 Aug 2002 07:45:41, you wrote:
> >  >Vary the ignition timing.
> >  >If man built it, man can crack it.
> >  >BobR.
> >
> >
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> >
> 
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