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Old 05-10-2008, 04:45 PM   #9 (permalink)
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Originally Posted by JohnnyGrey View Post
John, how are you certain you're in open loop, is the O2 unplugged?

No, the check light is on. The EGR is unplugged. Unpluging the 02 is an idea.

I tried doing this on my Cavalier, but the variation in AFR was too wild to run reliably for any length of time. I would advise against slowing down your pump. If it produces less pressure than the regulator needs to open, the fuel supply line will slow to a crawl and the return line will stop. Depending on the design of your pump, it may be cooled by the fuel that runs past it, which will not be much if you go below regulator pressure.

The pump in the tank is liquid cooled. The gas goes thur its motor.

Try finding an adjustable fuel pressure regulator instead.

I have a check valve in the vacuum line to the regulator to limit fuel press. to 36 PSI.
Be careful if you do this, because you will have leaned out your WOT mixture as well. If you need a sudden burst of acceleration, you could cause severe detonation. My car stays in closed loop at around 16.5:1, but if I stomp it, open loop is still around 12.5:1, so I can still get full power out of my engine safely.
JohnnyGrey, I would like to get into tuning these injected gasoline engines. What is a good direction to head so I don't have redundant equipment? What is the fifth wire on a wide band, temperature? I assume the other four are heater pwr, heater grnd, signal, signal grnd.

I'll look up this MegaSquirt.

Last edited by diesel_john; 05-10-2008 at 04:57 PM..
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