RPMs/Power Drops

[doberdann1019]

I have a 2009 XB12Ss with 15K miles. Sometimes when riding, the RPMs will randomly drop steadily at a rate of about 500rpm every second or two. I can feel it, feels like an engine brake and the bike slows down. To fix it I pull in the clutch and rev it a little until it jumps back up to normal, release the clutch and continue riding. If I don't pull in the clutch it might stall out or jump back up and jerk the bike back up to speed.

To fix it, I add HEET when I get gas. It seems to work, but I would like to know why its happening. I should not have to add HEET every tank. And it is pretty direct, if I add HEET its good, if I don't it will happen.

Also, when idling in neutral the RMP's will not sit, the jump around 1000rpms +/- 500rpms and when I am riding I can hear something in the air box opening and closing, air inlet valve maybe? It almost sounds like the bike is choking.

Anyone know what could be causing this? Two different harley dealers have not been able to fix it...and it could be dangerous if it dies while in a tight turn or heavy traffic.

 

[wrnglrx]

the airbox sound. Seems like your interactive exhuast valve for the exhaust is having some issues. it's supposed to open as your throttle position opens to allow more flow. then close while not at wot. Have you tried a tps reset?

 

[doberdann1019]

Is TPS throttle position sensor? - No, I have not tried that. How would I reset it?

 

[Theycallmecrash]

Kill switch off-
Wide open throttle-
Switch on while WOT- hold a second
Close throttle hold a second
Open and close 2 more times for a total of 3. Start bike.
Doubt thats the issue. Have you changed the spark plugs? If so with what?

 

[doberdann1019]

Thanks, I will try that tonight. Harley replaced the spark plugs at the 15K mile inspections last month. I am not sure what they used but it did not make a difference.

 

[go cytocis]

Did you get some dirty gas? I ended up with intermittent symptoms identical to yours on a recent road trip that took me to some pretty backwoods gas stations where I got tank after tank of shit fuel.
The problem resolved itself when I returned to high-octaine civilization.

 

[wrnglrx]

I have seen crystals form in the tank and clog the fuel pump. The fuel pump would starve as the fuel level would get between half full and empty. Took the fuel pump out, cleaned the tank out as much as we could and let it dry out then reinstalled the fuel pump with fresh gas and bam problem solved. no more surging and sputtering.

 

[doberdann1019]

Did you get some dirty gas?

I don't think thats the problem, I have only ever used 91 non-ethanol gas from Fastrac.

crystals form in the tank and clog the fuel pump

That could be it, I can look into cleaning the fuel pump.

 

[wrnglrx]

That would be awesome if we had that here in texas but all of our gas is laced with 10% corn crap.

 

[doberdann1019]

So I tried the TPS reset with no luck. I just took the cover off the air filter and found this cable to be loose, I know things are not usually designed to have slack in them. Think this could be the probelm? Does it control air flow to the cylinders? The shop manual calls this a "interactive exhaust", not sure what that means.

 

[doberdann1019]

I'm thinking that that loose cable controls the air into the engine and is not opening enough causing the engine to run rich. Anyone agree?

 

[doberdann1019]

so ignore that last post, looks like that cable controls the interactive exhaust system. see pic below.. my bike has a drummer ss exhaust on it, could this be part of the problem?

 

[doberdann1019]

It seems that with the Drummer, the interactive exhaust is not even used, so maybe that loose cable is not an issue.

 

[wrnglrx]

I would look into the fuel pump next. Since adding a fuel additive fixes it temporarily. I would steer there if it were my bike.

 

[Theycallmecrash]

This would be a good time to have ECMspy/tunerpro to view somethings. If you have a faulty oxygen sensor biased to read rich, it will cut fuel down and down until it near cuts off. Viewing the Air fuel value could give you some idea. Another possible problem could be as stated before Fuel pressure drops due to bad pump or regulator and starves the engine. Engine temp sensor, improper reading, could be flooding out during idle low speed travel.

When/what/where/how does your problem occur? Im still not exactly certain what it is wer troubleshooting. Try not to tell us what its "like" or what could cause it, give details to what its actually doing.

 

[doberdann1019]

What is involved in getting ECMspy or Tunerpro and which would you recommend?

I will try to explain the issue better...

The problem is that the RPMs will drop while riding. RPMs will continue to drop until I pull in the clutch, and then rev the throttle. I have not let the RPMs to drop past 1500 while riding.

I have noticed it in 3rd, 4th and 5th gear ranging from 30-70 MPH.

When I first start the bike RPMs will jump around 1000 (+/- 500) then eventually become stable around 1000 after about 2 minutes. Also, the bike is slow to turnover, I push the start button and it starts to turnover, pauses then turns over.

Once I start riding, when the RPMs will drop seems to be random. Sometimes it happens after 15 seconds, sometimes once the bike has been running for 45 minutes.

I have not noticed a correlation between engine temperature or air temperature. I happened at 60 degrees F yesterday morning and 80 degrees F yesterday afternoon.

I have noticed it happens more often with little gas in the tank, but has happened with a full tank (even with HEET). Usually with HEET and a full tank it will not happen. I use 2.5oz of HEET in a full tank.

I also noticed it only happens when I am moving a constant speed, holding the throttle steady. When it happens, I will hear a sound similar to metallic surfaces hitting or slapping each other coming from under the air box cover.

 

[Theycallmecrash]

Sounds fuel related. And when cruising the bike goes into closed loop. Bunch of complicated crap happens it leans out, and i bet your O2 sensor is a bit biased. I have had this happen myself. Bad sensor made bike think it was rich, got into closed loop and it fell on its face.

Ecmspy and tunerpro are both free software, a search will get you what ya need. The most important piece is the Communication cable ($50) that allows you to connect to the bike. Because your bike is a 2009 tunerpro is better suited for for tuning, but you can still use ecmspy to view data and reset AFV and such.

 

[Matteson]

Check the easy stuff first. All fuses and relays. We wiggled Justin's relay's last night because the bike was cutting out and found the issue. Replaced the bad relay. Start there. Then your battery and all connections to and from.

 

[ztied]

I agree with matteson . Simple stuff first,i posted somewhere else last night about check fuses and relays,and even flip the fuse box/relay box over and pop the cover off and make sure all the connections are tight on the back side.
I have experienced a small ground connector on the back side of the relay that was loose and it made lots of stuff not work.my inner voice told me to check the connections but my stuberness argued with it for 3days. So i gave in and checked it and that was it. This may not work for you but i hope its good info to help someone.little stuff stops big stuff.
Thats my $37.42 of advice

 

[Matteson]

Well Doberdan? Any status report for us?