Idle richness with 7747.

[Carl Summers]

Hi all,
  Sorry, haven't been following this thread.....is this a crossfire
conversion??? Sounds like wall wetting to me...unless you haven't worked the
areas your looking for.....if you have....and minimum pulse width is the
limiting factor...reduce timing at low rpms so injectors will come back to a
usable range.....more details needed....sorry...hate to use bandwidth for a
repost.....ttyl
-Carl Summers


-----Original Message-----
From: owner-gmecm at diy-efi.org [mailto:owner-gmecm at diy-efi.org]On Behalf
Of Kevin Reynolds
Sent: Thursday, March 09, 2000 10:37 PM
To: gmecm at diy-efi.org
Subject: Re: Idle richness with 7747.


No vacuum leaks I can find, just synced the TBIs, fresh plugs etc...
Yes the open loop idle is in O2mv's
I have a scanner, but have been using the open loop chip in combo with a
dash mounted autometer AFR gauge to make it easier to monitor O2 readings
while driving.
I've also checked the AFR and vacuum gauges against the scanner and am right
on with the O2 and off by 1inch on the vacuum.(20 reads as 21)
The fuel pressure is at 12psi, and since it can bring the 02 readings in
check once in closed loop there should be a way of doing this without having
to drop the pressure.
When I was running the closed loop enabled bin my BLMs where around 108, at
high vacuum and go leaner as the vacuum dropped. This seemed consistent with
the different cam and headers/exhaust. I have been working the VE table with
good success across the board, but at startup until closed loop kicked in I
get the 850mv. I've been using a non closed loop bin with the same tables as
the closed loop so now my idle richness is full time. At start up, with the
open loop chip, I get a high idle(2.3-2.5k) due to the richness, but after
the time it would take to go into closed loop(it doesn't, but same time
frame) the computer adjust down to target idle(close anyway, target 750 idle
about 800-850), but maintains the 850mv. Since it does this, I assume it's
trying to hit a AFR target (say 14 to 1)that is off due to my setup and is
more like 12.5 to 1. I've tried the AFR vs coolant map, changing from 13 to
15 from about 160degrees to over 200 and the O2 gauge didn't move even 50mv.
I did noticed there's a max and min AFR open loop setting listed in the
winbin file I'm using that isn't listed in tunercat. I thought maybe I hit a
cap and that was the reason for now change. So far I've only tried one burn
shifting the caps, but didn't get any change, but it needs more exploring.

Kevin R

> These 800 numbers, O2 millivolts?.
> Yep, that is rich, if nothing you do makes any changes try lowering the
fuel
> pressure.
> What kind of Block Learn Numbers are you running?.
> Is there a vacuum leak?.  I'd double check things tune-up wise just to
make
> sure you got a good foundation, to work with
> I usually roughed things out with 10% changes in the VE table.
> Do you have access to a scanner or diacom?.
> Grumpy
>

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