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7.3 and 6.9 IDI Pre-Powerstroke Ford Diesel Discussion

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Old 06-17-2013, 12:42 PM   #1
WisdomWarlord

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Surging

I have a 1993 F350 with a 7.3 L IDI diesel.

I have noticed several times that when I'm real low on fuel and I suck some air, the engine surges as if I have increased the throttle momentarily, but I didn't. By momentarily I mean more than a blip but less than 2 seconds.

That makes me think there is some gain to be had by somehow injecting air into the precombustion chamber along with the fuel.

Can anyone shed some light on what's causing this increase?

Thanks
 
Old 06-17-2013, 12:49 PM   #2
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Old 06-17-2013, 12:57 PM   #3
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Explain your logic.
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Old 06-18-2013, 07:54 AM   #4
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Extra-advanced injection timing from air in the injection pump screwing with the advance piston pressure.
 
Old 06-18-2013, 07:54 AM   #5
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Advance pump timing by 2 degrees for the same result.
 
Old 07-04-2013, 10:52 AM   #6
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I think I see. Hydraulic pressure influences pump timing, and air in the fuel supply changes the hydraulic pressure, so the result is actually an uncontrolled timing advance until the hydraulic pressure is restored. Am I over thinking that accurately?
I really thought I was into something there! :-D
 
Old 07-04-2013, 10:58 AM   #7
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@estrada5.9, my thinking was that maybe the air introduced with the fuel was atomizeing the fuel better and thus causing a noticeable improvement combustion efficiency.
 
Old 07-04-2013, 11:33 AM   #8
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Your thinking on the right path, in pre combustion engines the pre combustion chamber design is critical in making the engine either run pretty good or run like a dog. Although injecting let's say 150psi of compressed air into the pre comp. chamber might screw with how its originally intended to burn. And you might get a really bad running engine. Assuming you could figure out how to time the compressed air to hit on every injection event.


Fun to think about, but nowhere near practical.
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Old 07-04-2013, 11:55 AM   #9
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Interesting for sure sounds like one of those time and money consuming projects.

Good luck be sure to update as you progress.
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