Hello all. I'm new to the forums here, but I've been researching this issue for quite a while now and just wanted to see if I could get some additional input on what might be going on. There is quite a lot of backstory... sorry.

Here are a couple of links to videos of what the bike is doing at idle. It cuts out and there is an audible "gasp" which you can feel with your hand on the underside of the air intake.
Edit: Bike is a 2006 Harley Softail Deluxe EFI (FLSTNI)

Cold start (After maintenance)

Idling after an hour-long commute

Problem description:
Rough idling as seen in the videos. From a cold start, it is definitely worse but it doesn't ever completely go away. When first started, it will die a couple of times before settling on the rough idle (in the first video) without actually dying. When riding, the cut-outs will continue when on the throttle for a bit, until it gets "warmed up". At this point, it will maintain speed without cutting out for approx 20 minutes before starting to have issues again. When letting off the throttle (at any point) it backfires like crazy. 6th gear is useless with zero power until around 70mph.

After the bike is warmed up (after approx 25-30 min of riding) it will start to lose power while on the throttle. While going down the interstate at ~75mph it will start to slow and cannot pull even the slightest incline. Pinning the throttle provides no extra power, and the bike backfires constantly even with the throttle applied. After 30 seconds or so... it regains some power and goes like "normal" for a bit (normal meaning I can actually maintain or increase speed). Rinse and repeat. The second video above is how the bike idles after an hour-long trip like this which isn't much different from a cold start.

Shutting off the bike and restarting can get it to idle correctly for quite some time, but doesn't resolve any issues while riding. If the bike is sputtering bad enough, the check engine light will come on, but promptly goes off as soon as the sputtering is reduced. Over an hour-long commute, I will see the check engine light approx 5 times.

Steps Taken:
Here is where things get a bit interesting. My local Harley Dealer has had this bike in service multiple times in the last year. This last time, they had it for about 3 months. Both videos above were taken after I received the bike back from service to fix this very issue. (Note: I think they gave up on it, but they did me right and only charged me for a single, auxiliary, part that wasn't related to these problems... I don't feel I was taken advantage of). However, I could hear the bike doing this same thing as soon as the service tech started it to bring it to the front of the shop.

Here is a list of parts/repairs from the last service
- Internal fuel hose replacement
- 62PSI fuel regulator replacement
- Fuel regulator housing replacement
- New seals & clamp
- New ignition coil
- New intake seals
- New Idle Air Control kit
- New fuel injector
- New spark plugs
- New MAP sensor
- New top plate gasket
- Fuel treatment
- New Engine temp sensor
- New Fuel level sender (Auxillary part, not related)
- Fuel pressure test performed
- Notes: New fuel, tank parts, replaced intake seals all sensors on the throttle body, new ECM, new ignition coil, test ride good.

The service prior to this one ended up with me purchasing a new ECU which did not fix the problem.

Last year it was in service for a 20K mile tune-up as well as new tires, new bags, etc... not related to this issue. These issues began earlier this year in the spring (Mar/Apr timeframe).

Where I'm at:
I'm really wanting this bike to run right... but I've started looking for other options. I'm back to the point where I'm checking for intake leaks, suspecting a pin-hole in the fuel line, or trying to dive into the world of EFI fuel mapping. I've been scouring the forums and Google for anything and these are where I've been led to look.

My opinion is the fuel maps are incorrect... but I'm no mechanic. The fact this bike was in the dealership service dept for months, had all the parts above replaced or inspected, and is still having the same problem doesn't give me much hope of figuring anything out on my own.

This is why I'm posting here on the forum to look for any additional insight before I pull the trigger on getting rid of this beautiful bike.

 

I got the cobra power pack fi2000. Tunes your bike 80 times a second. My bike runs PERFECT no matter what. Try and find a tuner that fits your bike like the one i got and it may solve your problem.

 

I'm going to assume the fuel filter was replaced along with all the parts and the fuel pressure test was good . Fuel filter should be changed at 25k intervals . If a fuel pressure test was preformed , it should have shown signs of a plugged filter .

Things I would do , have the battery load tested , if good , follow the instructions on testing the ignition system , drop test etc , bad stator , regulator etc .

https://www.hdforums.com/forum/elect...sting-1-a.html

https://www.hdforums.com/forum/elect...sting-2-a.html

Check the connectors under the front of the frame , ( regulator , crank sensor ) when doing changes , oil runs down and saturates those connectors . Get yourself a can of electrical contact cleaner , clean those up and reconnect . Disconnect your battery , or pull the main fuse before disconnecting any connector and inspect for any loose / broken wires etc , clean and reconnect . It wouldn't hurt to go through all your connections , battery cables , ground points , fuses / box , check for corrosion etc .

Check the bike for error codes , if any , post up .

Pull the crank position sensor and inspect , clean it off and see if that causes any change . I have seen a couple cases where the crank sensor was going south and not showing an error , might be a good idea to just change it . I'm not into just replacing parts , but in this case , the price of it is worth a shot .

Keep us posted , welcome to the forum , good luck !

 

I tried a quick reply and it disappeared on me... I'm not sure where it ended up so this is try #2.

@Matth1991 Thank you for the response! I've been looking at the Cobra since you mentioned that, and I really want to give it a try. My gut is still telling me it is some kind of mapping issue.

@MyFavRk You assume correctly. The fuel pressure test came back good. The fuel filter was replaced in one of the previous services as well (I believe with the 20K mile service... but I'd have to re-check the paperwork).

I checked the codes last Friday before I left work. I had P1353 - "Front Cylinder No Combustion" which I cleared. I did not have a code show back up after riding home. Actually, my ride home was very good. I barely had any stuttering. The only difference was I rode about 5 minutes to the gas station for a fill-up before I left. It stuttered like crazy getting to the station, but after I left it performed better than it has in a while. To me, this seems something with the mapping and temperature sensor as sometimes shutting the bike off and re-starting it will get it to run a lot better for a while.

I'll check the other connections you mention this evening and see if I can spot any issue there. I'll definitely keep you posted. Thanks for the response!

 

With that code , I would check for a wear in the front spark plug wire , up close to the tank . Also , look at the front injector connector , could be a break in the wiring , a bad pin , corrosion etc .

 

What's the history behind the bike?

It simply sounds like it is running too lean or not enough timing.

1. What are the mods to the bike?

2. Check for intake leaks.. If there are any open spigots on the throttle body, plug them.

3. Is there any kind of tuner?

 

A bit of history:

I purchased it in early 2021. It had a new fuel pump and plugs prior to purchase.
I took it to get a 20K service and new tires, bags, etc. in April 2021.
Nothing mechanical was done throughout summer of 2021 (only cosmetic changes... bags, windshield, wind deflectors, etc...). The bike ran great. Went for rides nearly every weekend.
Sometime in Fall 2021, I was riding to work in the rain when I lost power, started sputtering, engine dying, etc... out of nowhere on the interstate. When it first started it would lose power and die entirely, but I would be able to clutch-dump restart it a few times before having to pull off the road. I rinsed and repeated this until it would only go a couple hundred feet without dying completely. Had to have a buddy trailer me home.
After that, I let it sit for a while (wasn't really riding season and I had other things going on) until late January 2022 when I took it to the dealer.
The bike wouldn't start at all when I got it to the dealership.
This was the first dealer service for this issue and it ended with a new ECU in February 2022 after they went through a couple of other sensors and thought the issue was fixed.
I trailered the bike back home, but the next time I rode it to work (in the rain again) it had nearly the same issue but not as bad. I pulled off at a gas station, filled it up, and was able to limp the bike back to the dealer.
That's where it stayed until recently and had all the stuff I mentioned in my previous post done.
This is where we are now. I still have the sputtering, but it isn't as bad as the first time it happened.... the bike will actually run, but not very well.

1.) Modifications: All stock except for the following...
Stock Exhaust: Baffles removed by the previous owner. This is the only mechanical modification.
I added a new rear seat, wind deflectors, saddlebags, and trunk.

2.) I've checked for intake leaks and was not able to find any. Have not checked the throttle body.

3.) No tuner (however I've ordered a Cobra Fi2000 as a shot in the dark. I have not received it yet.)

 

I think myfavRK could on to something. Check plug wires. I'd probably replace if you plan on riding in the rain.. Another favorite of mine issue is the connection at the bottom of the tank. When it misses hold hold up hard on the fuel line.. See if it goes away. You did not say whether they replaced the line going to the bottom of the tank.

 

Just an update

Over the weekend I tried a couple of suggestions as well as installed the Cobra fi2000. The short story is the Cobra did not correct the issue, but the long story is it made a noticeable difference.

I checked the plug wires. They seem fine to me. I wasn't able to notice anything out of the ordinary, but I did re-connect them to see if that would do anything at all.

I also tried pulling up hard on the under-tank fuel line both at idle and while inducing the sputter at low throttle. I wasn't able to get it to make a difference. I'm not sure if this was replaced at the dealer, but I know the internal fuel line was replaced. I thought the fuel pump part came with the external hose as well so I just assumed it would have been replaced as well.

While putting the Cobra on I was able to look at the injector connections as well as the battery, fuse box, etc. The injectors looked brand new (which lines up with the replacement list from the dealer) and the other connections looked good as well. I didn't find any cracks, breaks, or corrosion.

I didn't check for intake leaks this time since it was getting late, but that is my next step.

Notes after installing the Cobra.
It didn't fix the main sputtering issue on cold-start or at idle, however, it did seem to make quite a difference while actually riding the bike. I can feel a bit more power at lower RPM, and it seems to cut out a LOT less at constant or increasing throttle. The backfiring when letting off still exists, but is noticeably better. Basically, it seems to have smoothed everything out overall, but was still not able to take care of the idle "sucking/dying" or initial cold-start acceleration sputtering.

I rode the bike to work again today. Mostly the same story when leaving my house and going through town. Interstate was noticeably better with no power "loss". There were a few times I could tell the bike would start lagging a bit... but it came back and corrected itself fairly quickly. By the time I got to my work town, it was running correctly for the most part.

At lunch today, I took the bike to a Dr. appointment. It actually only sputtered once leaving the parking lot, but run completely normal for the rest of the ride to/from. No sputtering, no power loss, and it made me forget it even had issues. Even the idle was damn-near perfect when leaving my appointment and pulling back in. The ride was roughly 15 minutes in each direction, with a 30-minute break between them.

Now my debate is between keeping the fuel tuner or returning it. I feel like it's done "something" even if it hasn't fixed the main issue. Would I be on the right track of thinking it still may be an intake leak, but somehow gets better at higher temperatures due to expansion?

 

My opinion is to keep the tuner , only because it will help keep your bike cooler , and of course add a little more power to the bike . Running lean is never a good thing , especially if you ride during hot temps .

Wouldn't hurt to check the intake seals , do it while the bike is idling at temp , using some tb cleaner . Also check the seals on the injectors , if there is any change in the idle , I would focus on that .

Just a shot in the dark here , there's a small rubber cap on the throttle body ( Cali models ) wondering if your bike might have this and if it could be deteriorated , worth a look .

Another thought , crank position sensor ?? Not sure , the symptoms are not quite what it would be . I've seen a couple of bikes with poor idling , ended up being this , with no codes .