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Discussion Starter · #1 ·
This is my first Harley. I have a 03 Deuce with EFI. I upgraded the exhaust with the screamin eagle II slip fit mufflers and added the stage 1 air filter kit from screamin eagle as well. I had the dealer do the ECM calibration. The bike backfires when I de-accelerate. It really gives a loud backfire when I am coming off the freeway and downshifting and the RPM's are higher. I have talked with the dealer and they have told me that it is normal. I have ridden sport bikes for the past 20 years and did various upgrades to them. I still own a Honda CBR 929 with a power commander and it runs great. I believe a power commander will solve the problem. I have talken with 2 dealers and both have told me to stay away from the power commander. I believe the MAP that Harley is using is not dialed in correctly for my bike. I believe the bike is running a little rich and that is the reason for the backfiring. I have did a search of the forum and seen that some are having no problems and otheres are. They told me I could drop the bike off and leave it with them for several days and they would see what they could do. But they also told me they there is noithing they could do with the download and that they get it straight from Harley. I even talked with a local shop that works on Harley's and was told that the backfiring is normal. He did however tell me about a Digital Fuel Optimizer that is adjusted with a screwdriver and no PC is needed for adjustments for the EFI. I am new Harley owner and enjoy riding the bike. I appreciate anyone comments and help in this matter. Thanks in advance
 

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All you've heard and said so far is true. My '02 EFI Fat Boy is exactly the same way but it runs just fine. In my opinion, people need to quit thinking of this as a "problem". Listen to race cars with fairly open exhaust....they always backfire. I suppose you might find a way to reduce or eliminate it but I have decided to embrace it as part of the character of the twin cam. I think it sounds kind of cool.
 

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When you crank the throttle back to 0-20 percent at 4000 RPM or so and go into decceleration, your ignition immediately advances to the max roughly 45 degrees trying to get full burn and your manifold ambient pressure falls very low.
Often the fuel is still to rich so it goes unburned into those hot pipes and backfires.
You can ONLY address this on an EFI bike by modiftying the Eprom in the ECM. The dealer will not likley do or be able to do this but you need to lower the fuel in the specific area - or live with it.
 

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Same thing happens with my '02 FLHRI with SE II's. Dealer says it's the nature of the beast; it's a good shop and I trust 'em. I've learned to like it.

-jeff
 

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I guess i am just use to it. The harley doesn't back fire all that much. but i have a VW with race pipes and it backfires all the time. I just always chalked it up to intake and exhast mods on air cooled engines.
 

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Backfiring is NOT normal, if the dealer is telling you that they are full of crap. With all of the problems with EFI bikes, I thank God I bought the Road King Carb ...
 

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I somehow knew this was gonna become one of those "EFI is crap, glad I was smart and got a carb bike" threads. I appreciate your opinion Softgenious, but you offer no more insight or detail than the dealer when all you say is that it is NOT normal. Are you saying it hurts something. are you saying you know what is wrong. are you saying it means there is some problem at full or half throttle. All I know for sure is that a bike that backfires means you have a bike that backfires. what is it you know?

It can be fixed....all I'm saying is that I am not that worried about fixing mine.
 

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I guess enough backfiring would loosen things up but no more than "normal" vibrations would. My 01 RC has EFI and V&H slip ons. The only time I get popping is high speed decel (like a freeway offramp) especially if the engine is not fully warm. To avoid that I feather the throttle and use my brakes. If I'm going fast enough to really need a lot of engine braking, that popping out the pipes is the least of my worries. At least it makes the cars around you take notice.

tsuter is right. The only sure fix is a leaner fuel map over the affected range.

Patient: Doc it hurts when I do this.
Doctor: OK. Stop doing that :D
 

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Logical:

I never said that EFI bikes are crap! If you like your bike to backfire that's your decision, but it is NOT normal. I know owners of EFI and Carb bikes and none of them are having problems with backfiring...If you are stating that it is the character of the twin cam, you are very mistaken. All backfiring does is scare the crap out of old ladies...
 

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Discussion Starter · #11 ·
I appreciate everyone's input. It is interesting after reading on the forum that there are people that have no problems with the exact upgrade. I am going to continue researching this issue and will post my findings here.

I am presently doing some research on the Digital Fuel Optimizer (DFO) that is being sold through Custom Chrome for $ 189.95. It appears to work like this: It taps into the wiring of both fuel injectors downstream of the ECU. It allows you to performance tune across the the engines entire RPM range. The electronics of the DFO system intercept the ECU signal to the injectors and makes adjustments on the fly by increasing the signal and providing more fuel at a given throttle setting. Since the DFO works downstream of the ECU there is no risk of it being damaged.

The above was written straight from the pamphlet I was given from a local shop. There are four adjustments: 1) idle mix, 2) midrange, 3) top end, and 4) Sets RPM point at which the system transitions from mid to high.

If anyone has any experience with this porduct, I like to hear from them
 

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Digital Fuel Optimizer (DFO)-->Sounds very similar to the Techlusion product. www.techlusion.com.
 

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Softgenious said:
Logical:

I never said that EFI bikes are crap! If you like your bike to backfire that's your decision, but it is NOT normal. I know owners of EFI and Carb bikes and none of them are having problems with backfiring...If you are stating that it is the character of the twin cam, you are very mistaken. All backfiring does is scare the crap out of old ladies...
You maybe didn't call them crap, but you clearly implied they were fundamentally inferior. I never said it was normal, I just said it wasn't a big deal to me. I am not mistaken about the fact that it is very COMMON on EFI stage 1 bikes. And last but not least, I kinda like scaring old ladies.
 

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I would say it is pretty unusual for a stage 1 SOFTAIL to backfire.

There are any number of possibilities. The upload may have been corrupted, a vacuum leak, a leak on the exhaust system, etc. The Delphi bikes compensate for some vacuum leaks and can sometimes actually run rich because of this, as the difference in manifold pressure can have a bigger effect then the leak in itself.
Those slip ons are restrictive enough that reversion shoulkd not be a problem.

The DFO will not help you. They work very well but can only add fuel. If the bike has a rich spot on the fuel curve you can't take it out with it. It might work well if you return the ECM to the stock flash and then use the DFO.
One could also use the EFI tuner from HD. On small engines you can not beat it's flexibility.
Since the dealer can't make the flash work to your satisfaction, tell them to give you credit for the flash and pay them the difference to the tuner. You can use it to modify any flash in any way, except the stock flash.
 

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Logical:

You are a funny guy. I never wanted anyone to think that I thought EFI was inferior. When I purchased my 2003 Road King, I really wanted to go with EFI but after talking to numerous dealors and their customers I got the impression that Harley's EFI was not perfected. I also like the sound and rumbling-sputtering that the carb causes at a red light, I think the EFI smooths out the engine too much. All I know is we both are lucky to be able to be Harley owners. If I am ever in the Motor City and hear a large backfire I will know it's you...Be nice to the elderly...
 

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Can't we all just get along?:D

My 2003 Fatboy with Stage 1, Re-Flash and Vance and Hines BigShots Long will "pop" once in a while if I am heavy on the throttle and release quickly back to zero, and it's not much of a pop at that.

Remember, the louder the pipe, the more prevelant a backfire/pop would be (eaiser to hear).

I get a little poping, but that's about it...:(

Same as on my Superglide with Carb when I had it:eek:
 

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I count 6 threads on this forum alone about popping or backfiring stage 1 EFI bikes. Not normal, not common, not characterisitc, not right, not good, not bad, not unheard of, not a problem but a symptom of a problem but maybe not such a big problem but it depends on who you ask but don't ask me because all I know is what I know but that clearly ain't nothin but sure seems like it's not all that uncommon.

Errrrr...I thought we WERE getting along???????????

I kinda like the first gear clunk and the front brake drag noise and the valve train noise and the steering head creak too........but not near as much as the popping.
 

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Strange, call it a backfire or a pop, there is a difference. I know of many Stage one with open exhaust EFIs and all of them when you release the throttle at high RPM's and go quickly into compression, they pop. Just unburnt gas...

What else can I say!
 
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