Start up idle problem 2004 RKC
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Road Captain
Joined: Jan 2006
Posts: 601
Likes: 5
From: Pinellas County, Florida
Start up idle problem 2004 RKC
Cold start up the RPMs go up to 2500, then after I blip the throttle a few times they settle down a bit to surge between 1000 ad 1500. Then after it warms up, maybe 1-2 minutes all is good at 950 to 1000 idle RPM. I did throw a code for the TPS (p0122), so I replaced that to no avail. I also changed the plugs because it was popping out the left (rear cyl.) I did read something about spark plug ion sensing and how it could affect the ECM. Any ideas?
Thanks
Thanks
Road Warrior
Joined: May 2006
Posts: 1,650
Likes: 539
From: BHC, Arizona
Remove the air filter and look inside the throttle body, you will see the IAC pintle at approx the 11 o'clock position. open the throttle plate and place a shop rag in the throttle body.
While cycling the ignition on and off spray carb cleaner onto the IAC pintle. The shop rag is to catch the cleaner from running into the intake manifold.
After you have confirmed that the IAC pintle is moving normally, remove the shop rag and start the bike.
Hopefully your motor will start and idle normally.
While cycling the ignition on and off spray carb cleaner onto the IAC pintle. The shop rag is to catch the cleaner from running into the intake manifold.
After you have confirmed that the IAC pintle is moving normally, remove the shop rag and start the bike.
Hopefully your motor will start and idle normally.
Road Warrior
Joined: Nov 2014
Posts: 1,962
Likes: 140
From: NY
Cold start up the RPMs go up to 2500, then after I blip the throttle a few times they settle down a bit to surge between 1000 ad 1500. Then after it warms up, maybe 1-2 minutes all is good at 950 to 1000 idle RPM. I did throw a code for the TPS (p0122), so I replaced that to no avail. I also changed the plugs because it was popping out the left (rear cyl.) I did read something about spark plug ion sensing and how it could affect the ECM. Any ideas?
Thanks
Thanks
Well like has already been suggested 1st place to look is for a dirty IAC so chk that out.
But i would think if it was a dirty IAC causing unstable /searching idle when the motors cold then the idle would still be searching & or unstable when motors @ norm op temp too which isnt the case because you said it idles fine when motors warmed up.
So if cleaning the IAC doesn't fix the cold only unstable idle speed issue then look for an issue with some kind temp sender & or sensor etc in the cold start circut (closed vs open loop EFI issue) that may not be causing the unstable idle till motor /02's etc all reach norm op temp.
Now if you find that isnt the issue either then maybe there's a slight vacuum leak causing unstable idle till the motor ,02's & efi reaches norm op temp where it obtains info from 02's that are showing a lean condition due to a vac leak thus changing injector pulse to richen up fuel calibration enough to overcome the over lean mixture if that in fact is the issue to begin with.
Afterthought,you said bikes an 04 so is 12-13ish yrs old and just plug were changed recently,have the plug wires even been changed?
If not change them because you dont want to be chasing your tail just to find out the issue was caused by a set of 13yr old worn out plugs wires costing only $15-20 that are easy to swap out.
So now it's time to get cracking with the diagnostics & let us know how it go's along the way.
Good luck.
scott
Last edited by wscott; Oct 20, 2016 at 07:30 PM.
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,626
Likes: 6,443
From: Honah Lee
Pull the air filter. Now move the throttle and make sure you have some free play were the pull on and push back cables attach to the butterfly. Make sure the throttle drops back to the stop wit a metallic clack on the screw.
I have yet to figure out why but mine will get lost at around 2000 if I start it cold in gear and of course it surges fwd from the sticking clutch plates.
If the IAC goes all the way in when you key off and jumps back out when you key on, it's probably all right. Do not spray up into it. It will drive black crud up past o-ring into motor. Use a paper towel wetted to clean butterfly and area where it closes. Make sure throttle position is free and reads out properly on a resistance meter. (easy check)
2500 sounds to me like the cables out of adjustment
I have yet to figure out why but mine will get lost at around 2000 if I start it cold in gear and of course it surges fwd from the sticking clutch plates.
If the IAC goes all the way in when you key off and jumps back out when you key on, it's probably all right. Do not spray up into it. It will drive black crud up past o-ring into motor. Use a paper towel wetted to clean butterfly and area where it closes. Make sure throttle position is free and reads out properly on a resistance meter. (easy check)
2500 sounds to me like the cables out of adjustment
Last edited by Jackie Paper; Sep 14, 2018 at 10:18 AM.
Intermediate
Joined: Feb 2012
Posts: 49
Likes: 1
From: Charlotte NC
My o4 road king has done the same thing for the last 3 years. All I do is squeeze the brake lever after 10 or 15 seconds and it idles down to normal speed. I always thought this was normal. Never felt it was a problem.
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