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Old 08-06-2009, 06:27 PM   #57 (permalink)
cfg83
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1999 Saturn SW2 - '99 Saturn SW2 Wagon
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SentraSE-R -

Quote:
Originally Posted by SentraSE-R View Post
Deceleration fuel cutoff in my '02 Nissan Sentra and '06 Scion xB differs considerably. My wife's '06 Hyundai Elantra doesn't have it. So you can't tell from the age of the car whether it has DFCO.

Both the Nissan and Scion have to have the throttle position sensor at idle, open loop, transmission in gear, and rpms above a certain level. The Nissan's rpms have to be >2500. The Scion only >1500. So in sixth gear, the Nissan doesn't go into DFCO unless the car is rolling >65 mph. The Scion goes into DFCO at any speed above 35 mph. Both will stay in DFCO below the initial rpm, but they have to be above that limit to enter DFCO. In practice, I can let the Scion coast down any hill and be sure it's not using fuel. The Nissan, OTOH, has to be in a lower gear to get fuel cutoff.
Thanks for posting this. You made me look. I *do* have DFCO after all, just like the Nissan. Today I tested this going downhill in 3rd gear. It went lean until I went below 2500 RPM. I didn't see this before because I am below 2500 RPM most of the time. Because of the way I drive, I never saw it, .

This implies to me that I have a DFCO operating window. On steep (down)hills I can put the engine in a gear that keeps the engine above 2500 RPM.

CarloSW2
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Last edited by cfg83; 08-06-2009 at 06:59 PM..
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