2002, 22,500 Miles misfire. Very lean to very rich

Hi folks.

Last night on my ride home from work at had a sudden misfire, lost power and when I was able to get myself out of traffic and parked the bike wouldn't stay running. Exhaust gasses were VERY hot so I parked it and let it cool for a half hour. Pulled the battery while i was waiting to reset the computer and when restarted misfire was still there but now I could smell gas out the exhaust.

Picked up my trailer and got it home. Seems to be missing on the rich side now.

My plans are:

Empty tank, new gas.
Replace fuel filter
New spark plugs
check for vacuum leaks

Has anyone else experienced these problems and is there any other steps you would suggest?

Thanks

 

I'm of no use on this, but bumping your thread for you.

 

It could be a fouled spark plug or coil. Any FI lights? Do you know if the valve inspection has been done? I'm always a fan of doing a compression test, that would help rule out mechanicle issues. What mods have been done to the bike?

 

Finally back home and tearing into it.

FI lights were 23 and 24 O2 sensor errors but they shouldn't cause the bike not to run.

Pulled out the intake and the injectors are firing on all cylinders.

PROBLEM

I am only getting spark on cylinder #2 The rest are not firing. Im diving back into the manual now to continue trouble shooting but any advice would be appreciated.

I checked each coil on #2 cylinder and they all function properly.

 

Sounds like wiring harness issues then :O

When in doubt check all grounds!

 

The coils are wired straight from the computer. The fact that you have one coil firing and not the other three makes me think the computer is getting it's signals from the crank sensor to fire the coils. Hmmmmmmm I'm thinking faulty computer or maybe wiring to coils damaged, rodent damage/corrosion. The O2 sensor codes are probably from the rich/lean condition being too far out of spec. Like you say, It shouldn't keep bike from starting since the O2 sensors aren't used till they heat up and start giving a signal. If it is a faulty computer then when you replace it immediately check charging system! If it's charging voltage is too high then it could fry the computer

 

Tomorrow when i get home from work I will test the charging system. The recalls were all handled by the previous owner and all the wires "look" good. In Michigan the riding season just started a couple weeks ago and between work and travel I have only gotten 200 miles on it this season.

All 4 coils check out on #2 cylinder so I am pretty sure they are not the issue. If the Stator and Rectifier/Regulator check out I am leaning towards ECU. I will update after tomorrow. The spark was a weak orange spark.


Since it appears I love electrical issues, I bought an Aprilia today too....glutton for punishment or a learning experience?? Not sure yet.

 

Tested the stator and it has equal resistance across the 3 legs, also none of them ground out.

Couldn't get a running voltage because it wont start.

Has anyone used any of the ECU rebuild services from ebay or does someone feel daring enough to let me swap in your ECU for about 10 seconds?

 

I was off backpacking for the last 5 days but here is the latest:

Picked up a spare ECU to see if that would remedy the problem. Nope, still only sparking on one cylinder.

Next thought is to check the resistance on the pulse generator to see if its not picking up the crank position to send the spark.

 

Checked primary voltage to the coils last night. #1,3,4 are all at 7 volts, #2 is 12 volts.

Is there a common place where 1,3,4 wires would meet and I may have a break there?

I did check the firing wires for continuity back to the ECU and they are all good.

Thoughts?

 

Another update:

Checked max voltage from the ECU terminal that fires the coils. It is putting out 1.5V so it checks out.

Impulse Generator is putting out .15V with the minimum being .7V, hope I have found my problem. Also went through and sanded all the grounds I could track down.

Will report back this weekend.

 

Frustrating update:

Replaced the impulse generator and still misfire.

I am going to go through the harness again...anyone in Michigan want a side project? I would happily pay for someone to look at this.