Road King running on one cyl.
Thread Starter
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Road Captain
Joined: Feb 2006
Posts: 503
Likes: 1
From: AZ
Road King running on one cyl.
My brothers Road King started running rough on one cyl (front), missing, popping, backfiring etc.replacedthe plugs, nothing changed.It's getting fuel to the cyl so we know it's not that.
What would ya'll suspect? Bad plug wire or bad coil? Any other ideas?
We rode about 400 miles today, 60 miles on fresh gas, before problem started.
It's a 99 Road King Classic, EFI, stock except for high performance cam which was done years ago. No other mods. It's ran flawless until now. Serviced by the dealer per schedule.
What would ya'll suspect? Bad plug wire or bad coil? Any other ideas?
We rode about 400 miles today, 60 miles on fresh gas, before problem started.
It's a 99 Road King Classic, EFI, stock except for high performance cam which was done years ago. No other mods. It's ran flawless until now. Serviced by the dealer per schedule.
Tourer
Joined: Feb 2007
Posts: 382
Likes: 0
From: Long Beach, Ca.
RE: Road King running on one cyl.
ORIGINAL: Newhog
My brothers Road King started running rough on one cyl (front), missing, popping, backfiring etc.replacedthe plugs, nothing changed.It's getting fuel to the cyl so we know it's not that.
What would ya'll suspect? Bad plug wire or bad coil? Any other ideas?
We rode about 400 miles today, 60 miles on fresh gas, before problem started.
It's a 99 Road King Classic, EFI, stock except for high performance cam which was done years ago. No other mods. It's ran flawless until now. Serviced by the dealer per schedule.
My brothers Road King started running rough on one cyl (front), missing, popping, backfiring etc.replacedthe plugs, nothing changed.It's getting fuel to the cyl so we know it's not that.
What would ya'll suspect? Bad plug wire or bad coil? Any other ideas?
We rode about 400 miles today, 60 miles on fresh gas, before problem started.
It's a 99 Road King Classic, EFI, stock except for high performance cam which was done years ago. No other mods. It's ran flawless until now. Serviced by the dealer per schedule.
Administrator Emeritus
Joined: Jan 2005
Posts: 5,704
Likes: 252
From: Walker Basin, CA
RE: Road King running on one cyl.
It takes three things for an engine to run:
1) Proper air/fuel mixture
2) Adequate compression
3) A properly timed/adequate spark
You say you have fuel.
Have you run a compression test? If you have good compression and fuel delivery, it must be in the spark. Coil? Wire? Plug? Sensors? Just eliminate them one by one until you get it right.
Let us know what you find out.
1) Proper air/fuel mixture
2) Adequate compression
3) A properly timed/adequate spark
You say you have fuel.
Have you run a compression test? If you have good compression and fuel delivery, it must be in the spark. Coil? Wire? Plug? Sensors? Just eliminate them one by one until you get it right.
Let us know what you find out.
Thread Starter
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Road Captain
Joined: Feb 2006
Posts: 503
Likes: 1
From: AZ
RE: Road King running on one cyl.
Thanks Folks,
Sensors? Now that's one I've not thought of, let me be stupid and ask where they are or more importantly which one(s) you are reffering to?
Sensors? Now that's one I've not thought of, let me be stupid and ask where they are or more importantly which one(s) you are reffering to?
Outstanding HDF Member
Joined: May 2006
Posts: 3,273
Likes: 7
From:
RE: Road King running on one cyl.
you have an intake leak.
easy enough to check the plug fire, get an extra plug, connect to rear cyclinder spark lead, ground plug and turn engine over looking for spark.
easy enough to check the plug fire, get an extra plug, connect to rear cyclinder spark lead, ground plug and turn engine over looking for spark.
Thread Starter
|
Road Captain
Joined: Feb 2006
Posts: 503
Likes: 1
From: AZ
RE: Road King running on one cyl.
ORIGINAL: sleepneagle
you have an intake leak.
easy enough to check the plug fire, get an extra plug, connect to rear cyclinder spark lead, ground plug and turn engine over looking for spark.
you have an intake leak.
easy enough to check the plug fire, get an extra plug, connect to rear cyclinder spark lead, ground plug and turn engine over looking for spark.
I am very appreciative.
Thanks, Mike
Banned
Joined: Jan 2007
Posts: 2,301
Likes: 4
From:
RE: Road King running on one cyl.
Well is it fuel injected?
The sensors in and of themselves will not cause to run on only one cylinder.
All they do is feed information to the Ecm to process so the ecm knows if it should
adjust time the injectors are turned on (squirting fuel) if it should advance or retard
the spark timing.
so........
Two things you should check is compression in that cylinder.
But since you claim it was sudden I would expect ignition.
one side of coil could be bad, or the plug wire.
It is possible but not likely, that the ECM is failing and not suppling a ground
for one side of the coil, or the wire from coil back to ecm is damaged.
In an old points system when the points opened (you lost the ground), the electrical magnetic field that was built up in coil, would collapse. thus generating the secondary high voltage spark.
In the Ecm it does the same thing. Through the transistors, it completes the ground and the coil field builds up. When the crank sensor sends a signal to ECM that number 1 or 2 piston is at the right point to receive spark, Ecm turns off the transistor. Now no ground on that circuit and the field in coil (as in points above) collapses generating the spark.
So I would venture most likely the coil or plug wire has gone bad.
Take a new plug and plug into wire. Ground the metal tang (electrode) of plug to engine.
Crank engine look for spark. No spark,take other coil wire off and move to the number one spot and the number 1 to number two and see if problem moves. If it does it is the wire.
If not try another coil.
But do a compression test to be sure.
The sensors in and of themselves will not cause to run on only one cylinder.
All they do is feed information to the Ecm to process so the ecm knows if it should
adjust time the injectors are turned on (squirting fuel) if it should advance or retard
the spark timing.
so........
Two things you should check is compression in that cylinder.
But since you claim it was sudden I would expect ignition.
one side of coil could be bad, or the plug wire.
It is possible but not likely, that the ECM is failing and not suppling a ground
for one side of the coil, or the wire from coil back to ecm is damaged.
In an old points system when the points opened (you lost the ground), the electrical magnetic field that was built up in coil, would collapse. thus generating the secondary high voltage spark.
In the Ecm it does the same thing. Through the transistors, it completes the ground and the coil field builds up. When the crank sensor sends a signal to ECM that number 1 or 2 piston is at the right point to receive spark, Ecm turns off the transistor. Now no ground on that circuit and the field in coil (as in points above) collapses generating the spark.
So I would venture most likely the coil or plug wire has gone bad.
Take a new plug and plug into wire. Ground the metal tang (electrode) of plug to engine.
Crank engine look for spark. No spark,take other coil wire off and move to the number one spot and the number 1 to number two and see if problem moves. If it does it is the wire.
If not try another coil.
But do a compression test to be sure.
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Outstanding HDF Member
Joined: Nov 2005
Posts: 2,408
Likes: 2
From: Houston (Area)
RE: Road King running on one cyl.
Do you have a PCIII? I know you didn't say there was one installed. But my bike was acting like this and my PCIII would basically work when it wanted to and shut off. Dyno jet told me it had old firmware and had to update it.
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