Decel popping. I don't get it.
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Road Master
Joined: Feb 2010
Posts: 905
Likes: 51
From: New Jersey
Decel popping. I don't get it.
Can anyone explain to me what exactly causes decel popping. Vance & Hines has a setting on their FP3 that lets you get rid of some of the decel popping. They say it does it by dumping more fuel in the cylinder.
I don't understand how/why that works, because I guess I don't understand exactly what causes decel popping. Hoping someone can explain it to me, please.
Thanks in Advance
I don't understand how/why that works, because I guess I don't understand exactly what causes decel popping. Hoping someone can explain it to me, please.
Thanks in Advance
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
unburned fuel in the exhaust can be ignited when on decel fresh air ( oxygen) is drawn into the exhaust system from a leak in the joints or even drawn up from the tip. With some header designs, air can be drawn up the left side and added to exhaust at the Y pipe or collector.
the efi shouldn;t be adding fuel when deceling like it does when accelerating.
there are many variables- but too much fuel at any time is not good for the machine or for making power.
in a perfect world all the fuel burns inside the combustion chamber...any more than 500 ppm puts you in the same realm as a VW bug
mike
the efi shouldn;t be adding fuel when deceling like it does when accelerating.
there are many variables- but too much fuel at any time is not good for the machine or for making power.
in a perfect world all the fuel burns inside the combustion chamber...any more than 500 ppm puts you in the same realm as a VW bug
mike
Last edited by mkguitar; May 8, 2016 at 12:17 AM.
Thread Starter
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Road Master
Joined: Feb 2010
Posts: 905
Likes: 51
From: New Jersey
unburned fuel in the exhaust can be ignited when on decel fresh air ( oxygen) is drawn into the exhaust system from a leak in the joints or even drawn up from the tip. With some header designs, air can be drawn up the left side and added to exhaust at the Y pipe or collector.
the efi shouldn;t be adding fuel when deceling like it does when accelerating.
there are many variables- but too much fuel at any time is not good for the machine or for making power.
mike
the efi shouldn;t be adding fuel when deceling like it does when accelerating.
there are many variables- but too much fuel at any time is not good for the machine or for making power.
mike
Thread Starter
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Road Master
Joined: Feb 2010
Posts: 905
Likes: 51
From: New Jersey
Maybe I just thought my supposed friends on the forum could help me understand without confusing myself more with what I've read. If don't want to help me, please don't respond to the thread.
Seasoned HDF Member
Joined: Feb 2009
Posts: 5,642
Likes: 1,985
From: Cleveland Zoo
Good luck.
Road Warrior
Joined: Aug 2015
Posts: 1,712
Likes: 410
From: Puyallup, WA
As mm guitar said, developed pop I sunburned fuel burning in the pipe. If you of a carbureted bike; when you roll off the throttle, the engine is still turning, therefore it's sucking in air on the intake stroke.
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Seasoned HDF Member
Joined: Mar 2012
Posts: 100,455
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From: Centennial, CO
The Dobeck DFO/TFI does the same thing.asically the added fuel saturates the exhaust charge on decel thereby keeping the minor amount of unburnt fuel in the exhaust from "popping" when it hits the hot exhaust area just outside the port.
Last edited by QC; May 7, 2016 at 09:32 PM.
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Tourer
Joined: Nov 2012
Posts: 421
Likes: 71
From: Hayward Ca
Here is a doc from the Thundermax support docs that helps explain what causes decel popping and what they do with their software to help deal with it. I don't know anything about your tuner but at least this should give you an idea of what causes the problem. I have the feature turned on my RK and off on my Softail. Every motor and tune is a little different
http://www.thunder-max.com/techdocs/DecelPop1.pdf
http://www.thunder-max.com/techdocs/DecelPop1.pdf
