Yet another O2 sensor fakeout trick

[Mark Romans]

Hi James:  With a GM ecm (Unless it is some strange app) the ecm ignores the
02 sensor when at more than 70% throttle anyway. It goes into PE (Power
Enrichment) and goes to a richer commanded afr.  So making the 02 "Read"
lean won't change the pw.
Mark
-----Original Message-----
From: James Seabolt <jseabolt at intermediatn.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Saturday, May 15, 1999 5:09 AM
Subject: Yet another O2 sensor fakeout trick


>Thinking about trying yet another trick. I just can't leave this one thing
>alone. I would really like to get rid of my 5th injector. The fuel line is
>touching several items on the motor and I am afraid it might chap and
>spring a leak. Also it doesn't look very professional anyway. And the fact
>I am sure the injectors will provide enough fuel if I could just boost the
>pulse rate up a bit.
>
>Here's my plan.
>
>Since my pressure switch has three poles, I can wire it up with a resistor
>in parallel.
>
>When I hit the boost zone, the O2 sensor's output which is either .8 volts
>or .9 volts, however if I place a resistor between this circuit which
>brings the voltage down to .1 volts the computer will think the engine is
>running lean and increase the pulse rate trying to catch up.
>
>The trick will be to find the right resistance to create such a voltage
drop.
>
>I know there is a formula somewhere. What size resistor do I need to drop
>the voltage from .9 to .1 volts?
>
>I am also assuming if I need a little more fuel, I can increase the
>resistance some more.
>
>
>----------------------------------------------------------
>
>James Seabolt -----> mailto:jseabolt at intermediatn.net
>Webpage: http://users.intermediatn.net/jseabolt/
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>United States
>
>1980 FIAT 2000 TURBO Spider injected (John Deere aspirated)
>1981 FIAT 2000 Spider (Rest in Pieces)
>1981 FIAT X 1/9 (Injected)
>1994 JEEP Wrangler (2.5l )
>1976 Chevrolet Pickup (454 Big block/7.3 liter)
>
>----------------------------------------------------------
>