My motorcycle has recently started idling very low

[SAWYER]

It has never done this and not sure what caused it, it is fuel injected and I have not done anything different to it. Any suggestions?

 

[WilliamM2]

Does it have an idle adjustment?

 

[SAWYER]

I am not sure, guess I need to look in my service manual. I am wondering why it started doing it though

 

[sze5003]

What type of bike ? Your idle adjust screw could be loose? On my sv650s the idle screw is on the left side under the top fairing. Any fuel injection warning light ever come on?

 

[SAWYER]

No lights are ever on that I have seen and it is a Harley Fatboy

 

[Zenmervolt]

How low is "very low"? What did it idle at before and what does it idle at now?

There is no external adjustment for idle on the newer Delphi EFI Harleys (especially not with the recent models that use an electronic throttle). You'd need to have a programmer to change the idle speed.

Under what conditions is this happening? Is it all the time or only occasionally? If only occasionally it could be the temperature management systems coming into play. If the engine temp gets high, the ECU shuts off the rear cylinder (only at idle) and idle speed will drop a bit. If it's all the time, the idle control valve may be failing.

ZV

 

[Mandres]

I would run a little seafoam through the throttle body and see if it clears it. you might have a gummed up injector or some kind of enrichment circuit that's clogged.

 

[SAWYER]

Low enough that is is on the verge of dying and has a few times, especially if the clutch is in and I and downshifting from a road travel speed

 

[Zenmervolt]

Low enough that is is on the verge of dying and has a few times, especially if the clutch is in and I and downshifting from a road travel speed

OK, so you're closing the throttle with the clutch disengaged and the engine stumbles? When you sit still with the clutch disengaged is the idle lower then too? Or does this only happen when you're at cruising RPM and then disengage the clutch and close the throttle?

You can look to see if there are any stored codes in the EFI system (assuming a newer Delphi system) with the following procedure:

The IM (instrument module) is capable of displaying DTC's (diagnostic trouble codes).
Speedometer Self Diagnostics: The speedometer is capable of displaying and clearing speedometer, tachometer, TSM/TSSM and ICM/ECM Diagnostic Trouble Codes (DTC).

1- Turn Ignition switch to OFF & Run/Stop switch is to Run.

2- Push odometer reset button in & hold.

3- Turn ignition switch to Ignition and release odometer reset button. Background lighting sould illuminate, speedometer needle should sweep its full range and indicator lamps (battery, security, low fuel, check engine and cruise) should illuminate. The word “diag” should then appear.

4 - Push the odometer reset button once and you will see the selection menu "PSSPt" with the first P flashing.

5 - Each letter represents an area of the diagnostics module. The module that is flashing is the one you are going to check. To move from one letter (module) to the next, you push the odometer reset button one time. (from P to S to SP to t and back to P, etc.)
P = ECM/ICM (Electronic Control Module [EFI] / Ignition Control Module [Carbureted])
S = TSM/TSSM (Turn Signal/ Turn Signal Security Module)
SP = speedometer
T = tachometer

6 - To get the DTC within an area of diagnostics, push and hold the odometer reset button in for 5 seconds and release. If there are any DTC’s the code will be displayed or the word “none” will appear if there are no DTC’s. Push the odometer reset button again to view additional codes if they exist.

7 - Record the codes.

8 - If DTC’s are not to be cleared, Press and release the odometer reset button. Part number of module will be displayed.
NOTE: To determine if a code is current or historic, clear the displayed code by pushing in and holding the odometer reset button ( longer than 5 seconds) until 'clear' comes up. Release the odometer reset button. Turn OFF the ignition switch. Run your bike and shut it down then recheck the DTC’s again by repeating steps 1 to 9. If the code is current it will reappear.

9 – Press and release the odometer reset button to continue to the next module.

10 – Turn Ignition switch to OFF.

On models not equipped with a tachometer "No Rsp" will appear when the tachometer identifier is selected.

"No Rsp" (no response) will also appear if the run/off switch is in the off position when doing this procedure.

 

[sze5003]

I was doing some reading. A proper idle for your bike should be between 950 and 1050 rpm. Try the seafoam route as it's cheap. Yeah the idle for that bike has to be done with a computer.

It shouldn't be so low that it almost dies. Something is blocking the injectors or the efi system is going bad. Have you asked them what could cause this at a dealer or other bike shop? I'm pretty sure they would charge for a diagnosis but that's the thing with fuel injection of it goes bad it can be expensive if you are not up to work on it yourself.

 

[SAWYER]

If I am sitting in neutral at stop with the clutch in it idles low but doesnt die usually, but when traveling and I pull in the clutch it dies sometimes. I will try some Seafoam, I have never added any kind of additive or cleaner, I will at my next fill up

 

[Zenmervolt]

I was doing some reading. A proper idle for your bike should be between 950 and 1050 rpm.

That's generally considered to be the minimum range if you adjust the idle speed with a programmer. Stock they tend to idle between 1,100 and 1,200 RPM.

If it were me, I would look into cleaning the idle control valve. A gummed-up ICV is very often the cause of idle issues on EFI Harleys. Here's a video on cleaning it: https://www.youtube.com/watch?v=oK6KZcirHpg (Don't use brake cleaner like he did, use throttle body cleaner.)

ZV

 

[sze5003]

That's generally considered to be the minimum range if you adjust the idle speed with a programmer. Stock they tend to idle between 1,100 and 1,200 RPM.

ZV

Yeah makes sense. That's what it was for my ninja 250 although that was carburated and low idle meant it's time to bust out the carbs or play with the idle screw when it's warmed up so that it is set properly.

 

[Raizinman]

I would run a little seafoam through the throttle body and see if it clears it. you might have a gummed up injector or some kind of enrichment circuit that's clogged.

This: Like most bikes, has it sat unriden for a period of time? Is it possible that the gas in the tank is older than 4 or 5 months old?

 

[Zenmervolt]

This: Like most bikes, has it sat unriden for a period of time? Is it possible that the gas in the tank is older than 4 or 5 months old?

1) Gasoline lasts at least a year. 4-5 month old gasoline will never be a problem unless you've got a gaping hole in the top of the tank and water is pouring in. I have never had any vehicle have a problem even with year-old gasoline. Never. All I've ever heard are anecdotes where someone changed 6 different things and rebuilt a carb that hadn't been touched in a decade and then blamed the issue on the gasoline instead of the the other half-dozen things he changed at the same time.

2) Even ignoring that, bad gas would cause a persistent running problem, not just low idle.

ZV