Any hints on tuning for a big cam?

[Roger Heflin]

On Mon, 15 Feb 1999, Bruce Plecan wrote:

> 
> -----Original Message-----
> From: Tom Sharpe <twsharpe at mtco.com>
> To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
> Date: Monday, February 15, 1999 6:08 PM
> Subject: Re: Any hints on tuning for a big cam?
> 
> IAC motor trimmer?.  Can I ask for you to expand on that?.
> What for IAC count do you run at idle
> Bruce
> 
> 
> >Mine's about 20% rich at idle with 10 deg retard from normal. the iac
> >motor trimmer is also at minimum to reduce the hunting.    Tom S
> >

I checked any my IAC is pretty stable, the BLM's and INT's hunt
around, and after 30-60 seconds or more stabilize after rising and
falling several times.

It looks like to me that when the BLM are adjusted to make up for the
INTS the ints aren't lowered, and the BLM's get up to their peak
before the integrators are allowed to fall, and the integrators aren't
adjusted when raising the BLMS.   I am going to try patching some code
in to lower/raise the INT's when the BLM's are raised/lowered, to keep
the fuel mixture constant.  It looks like fuel changes are made to the
ints and the BLMS catch up, and then GM is relying on the INTS to drop
again, but this seems to make things unstable, and oscillate.

Other than the BLM's my car's idle is pretty stable, the rpms bounce
around a bit, but you can't see it really on the tach (only on
diacom).

			Roger