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Old 04-27-2006, 10:36 PM   #2
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Join Date: Feb 2004
Location: Humble, TX
Posts: 638

1998 SC2
Default Re: NA SOHC w/SAFC-II for increased mpg?

I have my SAFC2 set to run a little lean during normal driving. I have it set at -6% at idle and it tapers off to 0% at 4500rpm. I know the PCM will adjust for these values and I'm still running at stoich. I'm doing this on the theory that by reducing and perceived amount of air going into the engine(the SAFC only adjusts the MAP sensor signal), the PCM will advance the timing a little and that may help with better throttle response, increased low end power, or maybe slightly better fuel economy. So, in theory, I'm running safely at stoich with slightly advanced timing. Whether or not it works, I dunno. It's not hurting anything.

To do what you want to, you'd have to use the SAFC to adjust the fuel trims beyond the PCM's limit. That'll set off a SES light for sure. The PCM will fight your changes in closed loop within its limits.

15.59 @ 87.1 quarter mile
1998 Saturn SC2 *sold* What have I done!?


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