'04 Roadking intermittant idle problem driving me nuts!

[madhatter455]

First post on forum hope some kind soul can help. 04 Roadking, 67000 miles. Intermittently at idle (stop lights etc) the idle jumps, then sputters as I take off. While riding all is well. Replaced the fuel filter and both pressure hoses (1 had a small crack) but still giving me fits. What are the symptoms of a failing TPS sensor? ANY ideas appreciated.

[AirGlider]

Mad,

Try cleaning the IAC. Do a search. There are several posts related. Good luck.

AG

[madhatter455]

Thanks Ag, I cleaned it, still no luck. A little more info.
Doesn't seem to make any difference if the tank is full or low.
No difference hot or cool
75% of the time when I come to a stop, all is well. 25% of the time it will idle just a little higher than normal, then stumble when I take off.
I replaced the fuel filter, and both pressure lines inside the tank. Now I've cleaned the IAC. It runs great except for this exception. Acceleration is good. Can ANYONE tell me the symptoms of a malfunctioning TPS? A good bottle of something to anyone who can nail this. The bike is still under warranty, but the local stealership seems to do more harm than good to too many bikes and I'd rather fix it myself, but I'm running out of ideas. ANY other suggestions is GREATLY appreciated

[ViennaHog]

TPS is difficult to test. Can develop some 'static' that confuses the idle control. Few more items to look at: speed sensor, idle stop screw and throttle blade shaft.

Speed sensor tells ECM when bike is stopped. Weak/bad signal can cause issues. Clean it as a start

Idle stop screw loose (unlikely)

throttle blade shaft broken

Good luck

[madhatter455]

Thanks VH, I hate to sound like a dufus, but where the heck is the speed sensor?
I'm thinking of just replacing the TPS and if that doesn't do it, at least I have a spare.
I'd like to test the speed sensor but can't even find it in the manual

[ViennaHog]

Originally Posted by madhatter455

Thanks VH, I hate to sound like a dufus, but where the heck is the speed sensor?
I'm thinking of just replacing the TPS and if that doesn't do it, at least I have a spare.
I'd like to test the speed sensor but can't even find it in the manual

On top of the transmission, below the starter. Two wires with a rubber hood.

[madhatter455]

Thanks!!
As you are obviously way more knowledgeable than I am, your thoughts on the following?
While I've cleaned the IAC, the local stealership says 8 out of 10 times with my symptoms it would be the motor in the IAC going bad, and with 67,000 miles I can understand. For a $60.00 part does this seem a reasonable guess for replacement? It is still under warranty, but I've always felt that I can screw it up myself for less than the dealership, and also learn something in the process :-)

[ViennaHog]

Originally Posted by madhatter455

Thanks!!
As you are obviously way more knowledgeable than I am, your thoughts on the following?
While I've cleaned the IAC, the local stealership says 8 out of 10 times with my symptoms it would be the motor in the IAC going bad, and with 67,000 miles I can understand. For a $60.00 part does this seem a reasonable guess for replacement? It is still under warranty, but I've always felt that I can screw it up myself for less than the dealership, and also learn something in the process :-)

Possible and easy to find when you have the equipment and can perform a data run that records among other data the movement of the IAC. Probably easier to buy the IAC and test it.

[madhatter455]

Thanks again, off to buy parts and I'll let you know the verdict!
Have a GREAT rest-of-the-weekend

[madhatter455]

Problem fixed, it was the temp sensor. I replaced a few parts I didn't need to, but learned a lot in the process. Thanks for the help!

[ViennaHog]

How did you find out about the faulty temp sensor?