I have an 05 deluxe FLSTNI. For the past 4 or 5 weeks I have been trying to isolate the cause of a cough, sputter, miss - whatever you want to call it. I have checked the battery connections since I had recently installed a new battery, all tight. Done the intake spray test for a leaky gasket - no leaks. New plugs and wires and tried another coil. Cleaned the throat and butterfly of the throttle body. the cough / sputter usually occurs during idle or when running an even speed. I haven't noticed any cough during acceleration.....any ideas? I hate to keep shooting in the dark, but the next process in line I guess is to check the injectors then the fuel filter maybe???

 

What color were the firing tips of spark plugs that were changed?

 

They were almost white, running lean. But that was shortly after the cough / sputter started. I replaced the plugs and after about a week checked them again and they were an ash gray - more like they should be. Short of replacing the fuel filter and pulling the injectors, I don't know what else to check. Even ran 2 tanks of rocket fuel additive - still same problem. Any suggestion would be appreciated.

Thanks Chunk

 

Every stock Harley I have owned would cough or sputter as I gave it gas from an idle or from a low RPM. I was able to totally eliminate it with a proper tune. I had two can tunes that did not eliminate it and finally got a custom tune made up. My most recent tune was provided by Steve at Fullsac performance and it has been perfect. If your too lean on your existing tune that will cause the cough's and sputters.

The coughing / sputtering is not only annoying but extremely dangerous since it did it to me when I was giving the bike gas while coming out of a low speed turn. When it coughed the bike almost fell on it's side and scared the s**t out of me. If I wasn't able to correct it I was going to buy a Goldwing, thats how much it pissed me off.

 

Yea, In know what you mean. Mine spits sputters. I have a 2005 deluxe FLSTNI. It started out just doing it once in a while and gradually got worse. I have replaced, intake seals, exhaust gaskets, new plugs, new wires, coil - still the same. Seems like the rear cylinder fires intermittently. I've heard the CKP can cause this as well as a chaffed wire. Anyone with any ideas so that I may keep what little hair I have remaining in my head would be greatly appreciated...

 

Wild guess. You said you put in new battery. I'm wondering if you had a charging issue the whole time and now the new battery is running low and causing misfires due to low spark?

 

No, never had a charging issue, just an old battery that reached the end of it's days.

 

Incase you have a dirty injector try this stuff called sea foam in the gas. It's been around forever and will clean your fuel pipes,


Secondly...water in tank? Bad gas? Sorry...just trying to help.

 

Gliden, I appreciate your help, but no, gas is fresh and clean. I ran 2 tanks of rocket fuel through it and usually use an additive to keep moisture in check. Doesn't really seem like bad gas (I've ran into that a time or two myself) but this is been more than one tank of fuel with the issue in the beginning.

 

Have you actually put a true rms voltmeter on the battery when she's running to see that your getting no more than 15.5volts and no less than (I forget) 12 or 11.7. You need to reference a motor head or the manual. You've done a lot of stuff so far. I'm kind of stuck on you really knowing your charging system is putting out what the bike needs. Could be a regulator too but without putting a true rms meter to it you really can't rule it out.