[mkiv] ODB1 lean spot may be cured

[Alex Gregory]

The following is a pull with the GCC. As you can see I was not able to
lean it out fully before ~4200rpm. This tune was done by finding out
what percentage my injectors were over stock. In my case I have 780cc
injectors. So doing the math (550 / 780) means that they are 30% larger
than stock. In my case I have the B chip in the VPC which means that it
is doing part of that reduction for me. Finding out the difference
between 680cc and 780cc injectors, the difference is 20%. So in my case
I need to lean out the gain knob on the GCC -10% (difference between
680cc and 780cc injectors over stock). Once I did that I richened the
first three knobs as far as they could go, and then tuned the other two
on the top according to afr. With that I got these results:

http://www.spoooln.com/tuning/gcc.JPG

As you can see the AFR's are about ~12.5 and then really raise to ~14.5
just before they dip down to ~11.5 where they are supposed to be after
~4200 RPM.

After installing the AFC (with the VPC) I got these results:

http://www.spoooln.com/tuning/afc.JPG

Here they are almost 11.5 all the way across the band. I seem to have a
misfire in there in the middle so it looks like I do need to replace my
plugs. But as you can see I am pretty close to 11.5 from low RPM to
higher RPM's.

The characteristics of the OBDI ECU are different than the OBDII, but it
does seem that they are correctable. The point is that there are other
options other than just going with a standalone system, or going with
something like the emanage, or converting to OBDII. 

Alex G.
91' Syclone #411/2998
94' T-61 MKIV Supra
04' V70R 6-Speed
http://www.spoooln.com
http://www.forcefedfamily.com
mailto:spoooln at spoooln.com   

-----Original Message-----
From: mkiv-bounces at mkiv.com [mailto:mkiv-bounces at mkiv.com] On Behalf Of
Alex Gregory
Posted At: Friday, July 29, 2005 10:49 AM
Posted To: mkiv
Conversation: ODB1 lean spot may be cured
Subject: [mkiv] ODB1 lean spot may be cured


I swapped out my GCC for an SAFCII.  I am still running the AFC.  I
looked into the archives and set/wired the VPC up for hotwire.  So far
the results look promising.  I have gotten control under the 4200 mark
which I was not really able to do anything about before.  Since the
SAFC2 allows up to a -50 of leaning it out or richening it up it give
more room for adjustment.  I just started tuning on the way to work
today, so its going to take a bit of time to dial in since it takes a
bit longer with the SAFC2 than the GCC (12 points of adjustment that are
programmable rather than 5 preset points).  I will try and get some data
logs and take some screen captures and post them up.  Already I can feel
a lot more torque on the low end.  Its not easy to get somewhat of a 4th
gear pull in the bay area while going to work without putting anyone,
including myself, in danger. ;)  I will post more results later...

Thanks,

Alex G.
91' Syclone #411/2998
94' T-61 MKIV Supra
04' V70R 6-Speed
http://www.spoooln.com
http://www.forcefedfamily.com
mailto:spoooln at spoooln.com   

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