I need help! (idle issue on my 04)

cottbusa

Registered
You fella’s know hayabusa’s well, what would cause my 2004 to have surging idle??? Its all stock, & thus so far i have sync’d the throttle bodies, replaced both fuel filters, replaced spark plugs, replaced all of the vacuum lines, replaced intake boots (between tb’s & engine) & have made sure all sensor connections are good & clean, i’m at a loss on what to try next. Could the P.A.I.R system somehow be letting air in? Also has anyone had the o-rings fail within the throttle body assembly that could allow an air leak. This issue acts just like a vacuum leak. The bike runs perfect at every other RPM, this is an idle only issue with it.
 
Having had experience with six carburetor Hondas with six intake boots to the head and six to the airbox, a leak somewhere there is where I’d look first.
 
Also is there suppost to be a vacuum line connected to the air psi sensor? item #32. The reason i ask is there is a hose connection looking barb on the bottom side of the sensor that looks like a hose could/should slide on it? There is no hose on it now or a vacuum plug, nor do i see any extra hoses that would go to it, microfiche isnt showing a hose either been when you have hunted for this issue as much as i have i gotta ask about it.

D4BBAC96-FFE1-4F83-93F5-355CC88992A7.png
 
See red arrow is vacume hose IAPS
Yeah, mine has that vacuum line connected but there is another aps sensor that mounts to the LH side of the frame just below the airbox, it has the same looking barb as the sensor you posted up with the red arrow, the diagram you sent shows the iaps
 
I’m at witts end on this thing, i cant fine a vacuum leak, or anything to cause this thing to have a surging idle, i can back the idle adjustment screw all the way out & the bike will only idle down to 1100rpm, there’s got to be some sort of leak but its not in or around the fuel injection system. I have many hours into hunting this issue down & feel like beating my head against a fence post lol
 
Have you tried spraying some carb cleaner around the boots etc when it's running? Might show where it's sucking air.
 
(...) i can back the idle adjustment screw all the way out & the bike will only idle down to 1100rpm, (...)

trivial question (sorry in advance for the possible sillyness inside my question ;) )

but do you have that necessary little "gap" / "play" in your throttle cable
as like the manual said (2-4 mm "free turn" at the grip)
at THROTTLE CABLE PLAY, page 2-16 ?

if not, as far as I understand, the tps feels this,
reports this minimal opening of the flaps and the ecu sends a little bit (more than nec. for idle) of fuel to the engine - the idle increases / raises (a little)
no matter which screws you may have otherwise unscrewed .
 
@cottbusa

incidentally:
a too small/little (or totally missing) play in throttle usually also causes the jerking at constant speed, means unintended acceleration and deceleration in short intervals.
Yup i have sufficient throttle play, i even tried going super loose on the cable adjusters to try that but to no avail.
 
Back
Top