[Diy_efi] Re: IAC Counts and EGR during tuning

[Charles McDowell]

I'm confused.  If he has high BLM's, then he needs to boost the VE =
numbers,
right?  Best guess is (BLM/128)*current_VE, I think.  And if the pulse =
width
is not getting all used because of edge effects, wouldn't that only mean =
you
need yet a bigger VE number to account for it?

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] =
On
Behalf Of David Cooley
Sent: Friday, December 31, 2004 9:44 AM
To: A list for Do-It-Yourself EFI
Subject: Re: [Diy_efi] Re: IAC Counts and EGR during tuning


 I think you have that backwards...  Lower the VE at idle and low rpm's.
also, the Injectors may be slower opening than what GM called for and =
making
the low end PW actually be less open time than what the electrical pulse =
is
giving...

=20
-------Original Message-------
=20
From: Mike Frels
Date: 12/31/04 10:17:44
To: A list for Do-It-Yourself EFI
Subject: Re: [Diy_efi] Re: IAC Counts and EGR during tuning
=20
After my last round of VE changes and driving for scan data the idle has
settled down. It's now only at 11. This is closest enough to 10 to clear =
up
that concern.
=20
My injector constant in the AUJP is already set to 23.something or other =
for
the #24 injectors. Last drive and scan showed improvement but as is =
usual
with every good change comes something puzzling again. With my high =
RPM/high
kPa VE values in the 90s when dip into these higher kPa ranges(without =
going
into PE) my BLMs come down into the 130s. My low VE tables are still =
keeping
me way lean. For example sitting at idle with my VEs in the low 80s my =
BLMs
are still at 160 with long term fuel trim of 125%. The VE adjustment
necessary to get me to 128 would push a good range of VEs into the
100s...????...I have a hard time believing these Vortec heads and SDPC =
TPI
intake are THAT efficient to require that much fuel. I am starting to =
wonder
if I need to move to #30 injectors.
=20
Thoughts, comments?
=20
Sorry for not mentioning it earlier but this setup is in an 80's manual
tranny Camaro.
=20
Happy Holidays,
Mike
=20
At 09:05 PM 12/30/2004, you wrote:
>I would definitely disable EGR while tuning the VE tables. I also like=20
>to disable DFCO and Highway Fuel Mode. Any one of these 3 will throw=20
>your O2 readings off when they come into play, which messes with the=20
>INT and BLM. It might also be a good idea to play with the injector=20
>constant to get the BLMs a little closer before you start to tweak in=20
>the VE.
>
>Also, those are pretty high IAC counts for idle. You may have something =

>dirty/clogged blocking your airflow (clean the throttlebody just on
>principle) or your "minimum airflow" setting is off. I shoot for 10=20
>counts at hot idle in gear.
>
>That MAT reading is pretty reasonable. The sensor is made just like a=20
>coolant sensor (solid brass) and it soaks up a lot of heat from the=20
>aluminum intake. AFAIK it's only used to enable EGR, and possibly for a =

>fuel trim modifier in AUJP.
>
=20
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