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What does the fuel delivery system do when cruising down a steep hill and the rpms are steady at...

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Old 10-02-2006, 09:22 PM
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Default What does the fuel delivery system do when cruising down a steep hill and the rpms are steady at...
...around 4000 in 2nd gear? If the engine speed is induced to run at those speeds down hill(foot off the gas pedal) and the pistons are drawing vacuum, are the chambers still running at stoichiametric? Is the fuel system still delivering as though it had a load since air is rushing into the chambers at 4000 rpm? If it does not, what does our fuel system cause the combustion chambers to do at 4000rpm when the throttle plate is closed?
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Old 10-02-2006, 09:27 PM
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injectors are shut off.
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Old 10-02-2006, 09:42 PM
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you're saying zero fuel? so no combustion? ummm........
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Old 10-02-2006, 09:43 PM
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Default 2nd. Thanks to DAP's motronic book for teaching me the art of overrun.
Having this knowledge has altered my driving style to the point of improving my gas mileage substantially.
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Old 10-02-2006, 09:43 PM
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Default If they are really off wouldn't the car turn off?
From what I remember the injectors are injecting just not that much. 3% or 3 ms, I think ?

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Old 10-02-2006, 09:49 PM
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Got any ideas to what really happens in there under those conditions?
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Old 10-02-2006, 09:59 PM
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So basically the motor is just pumping air on the off cycle?
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Old 10-02-2006, 10:08 PM
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Default The injectors are off. the Engine is spinning due to mechanical coupling
Spark is still being delivered but there is no fuel until the rpms drop to 1200 or the accelerator is depressed and torque is requested
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Old 10-02-2006, 10:08 PM
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Default Yes read my post
<ul><li><a href="https://forums.audiworld.com/s4/msgs/2490040.phtml">here</a></li></ul>
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Old 10-02-2006, 10:10 PM
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That's all the engine is doing when there is fuel, so why would it change where there is no fuel
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