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Discussion Starter #1
I would like to ask for help. I have (moderate?) popping on decelleration, on my '02 FLHTCI, which occurs from about 3,000 R's to about 2,000 R's. Outside of that RPM range, things seems to be OK.

It has a H-D stage-1 reflash ECM, a SE A/C, and Khrome Werks HP-Plus 100 slip-ons. I have also installed a PCIIIr, with a map closest to my application (from their website).

The Powercommander website only has a map for the HP-Plus slip-ons, and not the HP-Plus 100's. So I am using the closest map available.

Is popping on decel caused from a too rich condition? As opposed to popping on accel, which is from a too lean condition?

Can I just lean out (make negative) the fuel values on the PC table, 0%throttle 2-3K RPM's?

I had tried a different PC map with a (-20) on all RPM's above 1,500 at 0% throttle, and it still popped on decel.

Any advice appreciated....THANKS!

Mitch
 

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Generally speaking the popping on deccel out of the exhaust is a rich condition (and popping out of the intake on accel is lean) but there are other possibilities.

Any cold air leak along the exhaust is going to cause popping on deccel, from a exhaust manifold gasket to a poor junction in the pipes or where the slip on is connected.
Then you have exhaust reversion, in particular with the Y pipe arrangement on the FLT's. Is is relatively common with some low restriction pipes, and with some pipes it is damn near impossible to get rid of it unless you block the left pipe at the Y.

While you can alter the maps, I don't know that I would do this indiscrimanetily for long without first establishing what the AFR is at any given rpm.
 

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Discussion Starter #3
Hippo, tahnks...

After thinking about what you wrote overnight, I wouldn't be surprised if it is some type of reversion like you stated.

After trying a map that was very leaned out (-20) on deccel at 1500 and over (0% T), and it still had the same conditions, that sounds like it. I am guessing that I don't have an exhaust leak like you mentioned, but that's just a guess. Funny, it doesn't really do it above about 3,000 on deccel. I guess I'll have to learn to live it, or have the bike dyno'd like you mentioned (I think that's what you meant). I'll probably have that done later.

Thanks, much appreciate your time...
Mitch
 

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I have a 02' FLSTSI with a Stage 1 and Vance & Hines straight shots and have the exact same condition you describe on decel. I've had it checked at the local shop and at one in Texas about 45 miles away (has a better reputation) and the both said that as Hippo pointed out, the less restrictive pipes is the culpret. Not much can be done to resolve it, so I've learned to deal with it and drive the folks I ride with nuts! As long as it doesn't hurt the motor, I can live with it. :)
 

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Discussion Starter #5
Skydoc, are you running a Power Commander?

I talked to PC, and they recommended making all of the 0% throttle boxes above 1,500 RPM's at -40 on the fuel table. I made the map, and will load it as soon as I can. PC says this won't always work. But I'll take any improvement.

You can see through the HP-Pluss 100's I am running. They have a reversion wave thingy inside, but there are no baffles in it...

I love the sound, though...

Mitch
 

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Discussion Starter #6
Results from above...

I performed the recco's from PC, per above.

It helped out some, but same problem is still there.

I guess if I wanted to eliminate this, I would buy "Balffed" muffs?

Mitch
 

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Popping

Hi Chiselchts, I had the same problem on my 2001 Ultra, with a stage 1 kit, PC II and Samson rolled over mufflers. I went as far as taking out fuel to -40 on 2500 rpm's and below and it only helped a little. The problem is reversion on open pipes like I had. I switched to Wild Pig Pipes,(mufflers) loaded a new map into the PC II and guess what, NO MORE POPPING in the mufflers. Be careful on what mufflers you put on these new EFI bikes.
 

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I believe has it to do with less restrictive pipes. I put on Bub True Duals with Bub Dresser Dogs with a 1 3/4" baffles and I got a lot of popping. I put on the PC IIIr, downloaded a map and no more popping. Then I changed out the baffles to a 2" baffles and the popping is back.
 

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There was a great post somewhere some time ago on this decel pop. I am NOT any sort of expert on Harleys or engines but this made good sense to me.

During decel you are closing off the throttle and reducing the fuel content of the A/F mix. This mix is not completely burned in the cylinder if ignited at all. This 'lean' mix accumulates in the exhaust where it occasionally is ignited which is the 'pop' you hear. The more open the exhaust the more you will hear it. I believe a richer idle circuit will help burn more in the cylinder and not in the pipe.
 
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