Surging and fast idle, don't worry, I fixed it.

[Idaho]

The Nomad ran awesome all the way from Idaho to Ohio. Tuesday was a hot day here and I was headed home from a short ride to visit relatives. Turned off of the main highway onto a street that heads through a seedy section of town and the bike started running strange. The idle speed picked way up and would not retreat with a blip of the throttle so I pulled off onto a driveway apron to check things out. Besides the fast idle the engine was surging and not maintaining a steady rpm. ???

Throttle cables were still tight. Only thing I could do at the time was grab the idle control knob below the right side dog bowl and turn down the idle. That cured the fast idle and made surging less noticable but it still was not right. On the way home it stalled at stops a couple of times and I could tell it was not not running right.

I'm thinking that maybe a hose plug came off from my mod with Chucksters dual plate system and maybe I need to get a toothbrush and Seafoam after the butterflies and throttle bodies. I picked up the Seafoam on the way home and after the bike cooled down I started into it.

Took off the right side dog bowl and disassembled the dual plate adapter. As soon as I pulled the top plate and air filter away one of the little rubber tube caps that was glued with silicone onto the idle control solenoid air tubes fell out on the ground. ;) My brother in law had some silicone sealer so I cleaned up the tube and inside of the cap and stuck it back on then went to work on the throttle bodies with a toothbrush. It was dark grey when I finished scrubbing. Put it all back together and let it set overnight to make sure the silicone gets a good cure before I fire it back up.

I was sure happy to see that cap fall out.

[glwilson]

Sorry to hear about the hassles... but glad to hear you found out what happened and were able to know enough to fix-it.

Ride safe Bud... we'll see you in MV. ;)

[ndbigfish]

Bud,
The seedy part of town must have been in OH, cuz no seeds will grow in Poky.

[Idaho]

Originally Posted by ndbigfish

Bud,
The seedy part of town must have been in OH, cuz no seeds will grow in Poky.

True enough...

[AlabamaNomadRider]

Glad it wasn't any more serious than that Bud. Also glad you were able to make the needed repair.

[macmac]

The title read Classic vac leak. It's what you found too. Make sure it and all other possible vac leaks are not vac leaks.

[bullman]

Bud, you came to Ohio and didn't bother to stop and say Hi!!! Glad you were able to find the problem.

[Idaho]

Originally Posted by bullman

Bud, you came to Ohio and didn't bother to stop and say Hi!!! Glad you were able to find the problem.

You are two hours away or it would have worked. Enjoy your summer up there on the lake.

Mac, after I put the bike back together and let the new silicone set overnight the bike runs like a champ again. No more leaks.

[ringadingh]

Bud, you have to make sure the hose and plug are free of any oil, or the silicone wont stick well. Im sure you got it fixed good now.

[Idaho]

Originally Posted by Ringadingh

Bud, you have to make sure the hose and plug are free of any oil, or the silicone wont stick well. Im sure you got it fixed good now.

I wiped the tube off real good and cleaned the cap out with contact cleaner then dried it up with a paper towel. Hopefully I got all of the oil off. Thanks for the tip though.

[macmac]

Little bit on vac leaks:

When something fails to be a seal and is after the throttle plate, behid it that is, un-metered air is allowed to breath into the engine. This can and usually is a vac line gone bad, or a cap gone missing. Any time there is a spit back out the carb/throttle body these lines can take a hit and be blown off.

Then what happens depending is the un-metered air will tend to match the present fuel and increase RPM untill the mix is just to lean to run the engine at all. Then the engine cuts out, and will almost stall if the leak is bad enough. If it isn't that bad you will get a too high idle speed and a lack of power try to get up RPM enough to move, and lag.

So when the leak type is 'Hunting' going up and coming down the air leans the mix increasing RPM to the point there isn't fuel mix enough, and then the rpms crash, but then fuel comes back the engine gags on too much fuel, clears itself and zooms back up in rpm again.

Smaller leaks often go missed a while and are found in terms of lack of power and hard starts.

Some times a gasket will go bad cold, then seal itself up hot. Sometimes it's the other way around too. These are thermal vac leaks that seem to cure themselves and they do but it's a matter of time before they will be come all the time leaks.

Anyone with capped off ISC's tubings on a stock backing plate should check the caps that were installed once a year if not replace them by habit once a year.

There are vac lines on the intake manifold too that should be checked once a year if not get replaced. The ends dry out and get brittle swell and crack. Both ends but the engine side gets the worst beating. Usually the centers of these lines are not effected so baddly, but if routed incorrectly will chaff thru and so the center of the lines can be suspect.

Throttle plate shafts holding the throttle plate in a body or a carb must seal too. Vacuum is always behind a closed throttle plate and remains there till the throttle plate is at WOT.

[blowndodge]

I wonder if that's why once in a blue moon I've noticed a slight surge at slow speeds.. I've been trying to adjust this out with me TFI but it will still surge very slightly at 2500rpms..

[yoda]

This is interesting to me. My 07 started surging at idle when cold several months ago. Then it stopped surging when cold, but know surges at idle when warmed up. It also takes two hits on the starter to stay running most times. It starts, then dies. Hit the starter a second time and it stays running. I guess I need to check all the vac lines.

[upside22]

My 2007 surges when cold but not at an idle, just when I am trying to get up to highway speeds. With a steady throttle it works fine, only happens with acceleration. After five miles or so it goes away. I always put it down to the fuel processor "wandering" a bit when cold. Could it be a vacuum leak?

[macmac]

BD, Yoda, and Upside, All 3 of you most likely have vac leaks. If you have ISC's working check the lines past them, check the vac lines on the throttle body and the intake manifold and check the injector seals too.

One way it to mist WD-40 right into the intake. What ever you hear there, you can expect to hear once you 'shoot a leak', except a year or so ago I was testing with a new can with the built in wand and it didn't act like a easy fuel. I can't know if they changed WD.

The next best way is with a old fashion plumbers torch head NOT LIT, on a can of propane.

I liked the WD because i could see where I misted.

Checking one end of a vac line won't cut it either. Ya gotta check both ends.

BD I might not be surprised to find you had a long time vac leak at this point.

Yoda yours might be a bad intake gasket/Oring. The cold / hot cycling moves metal and stuffs O ring sometimes. One of 3 places on the manifold to the throttle body and the heads.

Upside yours could be in any of the above. I have no idea if the ISC's are working or not on your bike.