I have been riding my F4i for awhile but just joined recently in search of some help fixing my bike. When I first started riding this season, around April, the bike had developed a "miss". When I am just cruising, steady throttle, usually around 4-6,000 rpm every once in a while the bike will "cut out". When it does this the bike will lose power, the rpms and speed will drop till a certain point and then its like something "catches" and the power comes back and I regain my rpms and speed. In trying to diagnose the problem I have replaced my fuel filter, fuel pressure regulator, ignition pulse generator, I have pulled my injectors out and tried to clean them by soaking in fuel injector cleaner and carburetor cleaner and pulsing them on and off. other than this the bike runs fine still has pretty good I am stumped and would appreciate and help you guys could give me.
Thanks, Joe

 

Did you replace the spark plugs along with everything else you did? Checked all vac lines? How often does the problem happen?

 

I have not replaced the spark plugs since this started happening but I had just replaced them last summer (June 2012). I looked over the vacuum lines the best I could when I was taking the fuel injectors in and out, it doesn't really act like a vacuum leak though because when it's warm idles real smooth at just over 1000 rpm. It does it at least a couple times every time I go out and ride.

 

You should definitely replace the spark plugs, and maybe test the resistance of the coils. Its really hard to understand whats going on without seeing the problem, it almost sounds like an electrical issue.

 

Does the tachometer flutter or the red fi light flicker at all? I had an identical issue and ended up being the contacts for the kill switch internally corroded. I also have had issues with a grey connector (under the left hand air intake cover) having corrosion almost invisible to the eye.. and the bank angle sensor losing contact resulting in a die, crank no start until reset with the key. Shorted battery will cause this too... and tps normally crap out in a cruising range.. Number one crapper with no real rhyme or reason is a map sensor... causing the engine to fall on its face temporarily. A lot of people on here have reported blocked or partially blocked vacuum lines to the map.

 

I will try taking the spark plugs out and seeing what they look like. Problem is I just keep buying new parts for it and its getting expensive. I was wondering if I could be the coils, tps, or map sensor? I didn't know if there was a way to test if the coils are still good because I'm sure they are very expensive. I haven't tested the Map sensor electronically but I pulled the vacuum line to it off and made sure it wasn't cracked and leaking. I tested the tps when cleaning the injectors and I remember it having a smooth transition in ohms all they way up until almost full throttle ( I'll say about 3/4) the ohms went to 0. I didn't give this much thought because my meter is pretty crappy and I was in the middle of cleaning the injectors. I will check the bank angle sensor, although I think a previous owner may have disabled it because I have accidentally dropped the bike in the driveway and I remember it kept running. I just want to try and figure out whats wrong before I throw a bunch of more expensive parts at it.

 

I wish I could get a video of what it is doing but I never know when its going to happen. This is the best I can explain it: It happens most often when cruising the highway at about 50-70mph I will be in about the 4500-6000 rpm range and it will begin to "cut out" with no rhyme or reason. When this happens the bike will slowly lose power and I will usually lose about 5-10mph. The bike might stay at this speed for just a sec or maybe a good 30 sec or more and then without me doing anything something will "catch" and the power will come back and I will gain back my 5mph. I can't remember for sure but I think if I would open the throttle and get in to some power/more rpms it would get the bike out of the power slump.

 

Testing the coils is fairly easy you will need a volt/om tool and read the resistance between the pos and neg connections. I'm not sure of the tolerance but its something that you could probably google.


What you are describing I have only ever seen something similar twice, one instance it was a faulty TPS and the other was an O2 sensor. If you had a diagnostic tool you could record the perimeters in the computer it would be simple to find whats failing. You could just delete the 02 sensor see if that solves your problem.

danmoto makes a cheap "kit"

 

Ok, now that you mention it I have a dent in my exhaust right about where the o2 sensor is from when I dropped the bike last season just before I stopped riding it from cold weather. I just an O2 eliminator so will see if that does the trick!

 

The O2 sensor eliminator fixed it! Thanks Froasty!!