[Diy_efi] Re: IAC Counts and EGR during tuning

[Mike Frels]

Sorry!... Poor English in my reply. I should have said "My low rpm VE 
tables" instead of "My low VE tables." I a believe it was my bad that 
caused the confusion. I had not had enough caffeine yet at that time of 
morning. I am better now...

To clear it up a little my low rpm VE tables in the idle area and at 
slightly higher rpm and kPa are in the low to high 80s with 160 BLM 
readings. This why I am saying the required changes would put me over 100 
VE numbers.

Mike

At 10:31 AM 12/31/2004, you wrote:
>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...
>
>
>-------Original Message-------
>
>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
>
>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.
>
>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.
>
>Thoughts, comments?
>
>Sorry for not mentioning it earlier but this setup is in an 80's manual
>tranny Camaro.
>
>Happy Holidays,
>Mike
>
>At 09:05 PM 12/30/2004, you wrote:
> >I would definitely disable EGR while tuning the VE tables. I also like
> >to disable DFCO and Highway Fuel Mode. Any one of these 3 will throw
> >your O2 readings off when they come into play, which messes with the
> >INT and BLM. It might also be a good idea to play with the injector
> >constant to get the BLMs a little closer before you start to tweak in
> >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
> >counts at hot idle in gear.
> >
> >That MAT reading is pretty reasonable. The sensor is made just like a
> >coolant sensor (solid brass) and it soaks up a lot of heat from the
> >aluminum intake. AFAIK it's only used to enable EGR, and possibly for a
> >fuel trim modifier in AUJP.
> >

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