I think we need some more dirty sanchez talk about now.

Mike

Mike Hugill
Principal Recruiter
Evergreen Group, Inc.
P.O. Box 536
Garrett Park, MD. 20896
(301) 942-8168
mike@evergreengroupinc.com
www.evergreengroupinc.com
YahooIM: evergreengroupinc
----- Original Message -----
From: "Mark Keller" <kelphoto@ISLANDNET.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, December 21, 2001 1:23 PM
Subject: Re: Boston Bobs day at the dyno

> Hi Bob,
>
> As you may know I have the adjustable fuel pressure regulator sold by CB
> Performance.  Currently I run at 45 Psi or 30 psi above atomspheric and
> have enjoyed the tweaking of the AFM to accompodate this pressure
increase.
>
> A couple of thoughts I had. One is that the 22d ECU does not set a full
> rich mixture at WOT like the the 22 ECU, per Darrell Boehler.  Second
> the  BoECU seems to have a rather slow cycle for high power setting, ie
> the fuel mixture stays in the lean part of the specturm too long; rather
> that just setting an ideal power mixture of 12:1 vs the more less cycle
> 14.7 of stoimetric. The result under sustained WOT was a gradual loss in
> RPM as the engine would opperate on the lean side of the gate and as it
> moved to richer it would hold RPM then again lose RPM as the leaning
> occured-- a rachet effect of losing RPM. I believe the "chip" reverse
> this as you observed.  My feeling was this may have been an engniering
> design to govern the engine's for durability in the light commercial
> truck operational profile; better for fleet owners, but not for tweeking
power.
>
> I conducted these test on consistent grade hill climb of about two
> miles.  The speed and Rpm changes at the finish were compared as I made
> changes in my system. My best efforst were open loop and the AFM and
> fuel pressure set to deliever a .86 volt reading on the O2 at 4400 RPM
> gave me 8 mph more that Closed loop with the same fuel pressue-- a gain
> of 12 mph over stock fuel pressure.
>
> I observed in open loop, without O2 sensor feedback, that the curve on
> the AFM wiper signal and spring tension coupled to the ECU RPM/ fuel map
> still maintained the O2 voltage within the .3 to .7 volts during
> driving. The exceptions being WOT and decel which the injector are
> turned off above 2200 RPM or so. I was even able to tune spring tension
> and wiper position on the system so that as the vacuum approached the 5"
> mark, the fuel mixture began to move above .75 volts to the a maxium
> power mixture of .86 volts, and the system would run leaner at beginning
> at the 12" inches, to the .3 volts and below- thrilling! My fuel economy
> is better at cuise, but less at stop and go.  22 hwy, 17 city, so my
> average of 20.5 is down to 19.5-- the price of power.
>
> Unforuntaely I can't run open loop all of the time. The fine tuning is
> ok, but the ECU 22d does not use the TEMP 1 senor, air temperature, to
> modify the Fuel map , except at or below freezing, where it then richens
> the fuel mixtue 20%.  I discussed this with Darrel briefly and he said
> older 022 ECU models did not ignore the Temp 1 duining normal
> operations, but the 22 D does.  The upshot is that seasonal changes and
> even daily changes of 10 degress affected my tune at WOT only.  More
> temperature swings did affect the cruise mixture.
>
> At this point  to be safe, I just take the nominal gain of 4 mph with
> closed loop as opposed to an additionl 12 mph open loop at the higher
> than stock fuel pressure. The O2 sensor then provides temperature
> compensation until temperatures drop to 40 degrees. Then I drop the fuel
> pressue a touch in the winter to avoid the chugging that occure due to
> the Temp 1/ ECU  low  tempertaure adjustment; it still happens but for
> less that 15 seconds or so, compare to a minute or more if I let the
> fuel pressure stay at the summer settings. The system also passed
> emmisions testing with the higher fuel pressure and closed loop.  For
> the cost of the fuel pressure regularor, and new fuel lines, clamps and
> my labor, I feel this is a good way to increase performance and as you
> mentioned, fuel mixture is one that many owner's overlook.
>
> In the future I'd like to get an older 022  ECU that goes WOT, and uses
> the TEMP 1 senor during normal operation to experiment with.  BTW I've
> written more about these issues and timing as well, I'm at 45 BTDC at
> 3000 and premium gas, Chevron 91, in the archives, just search under my
name.
>
> Sincerely,
>
> Mark Keller
> 91 Carat
>