Ignition Problem?

wjbertrand said:
It occurs to me that it's been a few months since I updated this thread. Sadly my ST stills sits in the corner of the garage awaiting a moment of inspiration and motivation to try the next thing. Since the last update I have done a few additional things:


  • Left the bike at a local shop (Jett Tuning) with a great reputation. They were able to confirm the cutting out problem but not able to locate it. What they did do was to prove there were no mechanical problems. Compression was 195 -205 PSI and leak down was 5% across the cylinders. not bad for an engine with 150K on it.
  • I think I've determined that the problem starts to occur once the bike is fully warm and switches into closed loop running mode. The bike runs in open loop while warming up or at full throttle, conditions where the miss is not present. It also runs in open loop above about 50% of redline. That works out to be pretty close to the 4250 RPM where I experience the misfire. At higher RPM, under deceleration or at constant throttle, the system runs in closed loop mode. The difference between open and closed loop is that the ECM uses O2 sensor data in closed loop. I finally convinced myself to change the O2 sensors. Unfortunately as with everything else, this had no effect on how the bike runs.
  • All grounds and ground cap assemblies have been thoroughly inspected with nothing but pristine looking results.
  • All the sensors have been replaced or tested, so I am now left with suspicion of a fault in the main harness.
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Well maybe replace it with this http://www.ebay.com/itm/05-Honda-ST...ash=item25b253231a:g:V40AAOSwEgVWRPxT&vxp=mtr
 
970mike said:
Well maybe replace it with this http://www.ebay.com/itm/05-Honda-ST...ash=item25b253231a:g:V40AAOSwEgVWRPxT&vxp=mtr
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Thanks Mike, I've actually seen that one (hence my "wanted" post on the forum earlier today) unfortunately that one is for a non-ABS bike. Completely different harness to the ABS one. Good price though! There is/was an eBay seller with a 2005 ABS harness for sale, but he's telling me a wrong part number that doesn't even come up as an existing part. I even asked him to double check. The only thing I can think of is that it's for a non-US bike or something? At his $125 asking price, I'm leery of taking a chance.
 
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v8-7 said:
Maybe try replacing the O2 wire from the sensor to the ecm ?
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Before you spend the dollars for a Main Wire Harness (ABS), you probably should take a close look at the crankcase Sub Wire Harness that connects to both the knock sensor (RH side) and the neutral switch, as Mr v8-7 has suggested.

With 150,000 miles, that sub-harness has been cooked to the point where the insulation is probably falling off the conductors, and the wires have become very brittle. I think I would avoid purchasing a used sub-harness, due to the harsh environment it operates in, besides a new sub harness (32109-MCS-700) shouldn't be more than $50, cheap for the peace of mind.

Note: I replaced the sub-harness on my 2006 ST1300A, with 120,000 miles six months ago. During removal of the sub harness, the RH side conductors were found to be as stiff as a piece of welding wire with no flexibility, and the neutral conductor insulation was nowhere to be seen. The bare conductor strands of the neutral conductor were breaking as I manipulated the sub-harness out of the motorcycle chassis.​

As you may already know, the Main Wire Harness (PN 32100-MCS-710) for your 2005 ST1300A is also used in model years 2004 through 2007. I think purchasing a used Main Wire Harness does not carry the same risks of damage from overheating that the sub-harness has.
 
Thanks, I've inspected that sub-harness and unlike yours mine appears to be in really good condition, wires and insulation are nice and flexible and no sign of burning or damage to any of the connectors. I actually had to replace the neural switch a couple of years ago when it was damaged in a crash. So it's relatively new.


-Jeff
 
Bit the bullet and bought a replacement main harness off of ebay today. $125 but cheaper than the $500+ for new from the likes of Service Honda or Partzilla. I also have a set of alternator brushes. Someone suggested that worn brushes could arc and throw some RF noise, perhaps causing some erroneous signaling back to the ECM? Seems far fetched but at 150K miles probably not a bad idea to replace them anyway.

Don't know when I'll have the motivation to tear back into it but at least I'll have the parts on hand when the mood strikes! Perhaps the process of digging this much deeper will reveal the culprit if this isn't it.
 
World's first ST1300 spinal cord transplant! Got my Eastern Beaver connectors today and repaired the Donor harness. Quite a bit of disassembly to get the harness connectors around and through the frame. Had to loosen the entire rear subframe, rear fender, gas tank and countless other bits. Got the old harness out and the donor harness all threaded and into place. Tomorrow I'll work through making the connections. Looks like they ended up in all the correct places more or less. That's the original harness on the floor.

b65a45b279078b616b8da05440bad74a.jpg



-Jeff
 
Holy Mackerel that is a lot of disassembly!!!

Hope the going-together goes well.
(AND I really hope this cures the dead spot!)
 
Well no joy. The bike fired up immediately and idled fine, no FI codes. But the misfire is exactly the same as before all the work. [emoji35]


-Jeff
 
wjbertrand said:
Can't be that with 5% leakdown scores and 200-210 PSI compression numbers.
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Gremlins? I know you've tried about everything except cremation of the thing! If it's 'firing' at the wrong time, maybe a stretched timing chain or worn gears(on the 11 I guess it would be a belt)? Just idle speculation on my part since you've already covered the obvious.
 
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I can't remember everything that has been suggested so forgive me if this is a repeat. I am wondering about the bank angle sensor. It supplies voltage through the bank angle sensor relay to quite a few things, like injectors, coils and fuel pump. The output of the bank angle sensor relay is on the gray and black wire which can be tested at the service connector quite easily. I can't really imagine the bank angle sensor failing in a way consistent with your symptoms but we are reaching for straws here. I hope this helps.
 
woodybelle said:
I can't remember everything that has been suggested so forgive me if this is a repeat. I am wondering about the bank angle sensor. It supplies voltage through the bank angle sensor relay to quite a few things, like injectors, coils and fuel pump. The output of the bank angle sensor relay is on the gray and black wire which can be tested at the service connector quite easily. I can't really imagine the bank angle sensor failing in a way consistent with your symptoms but we are reaching for straws here. I hope this helps.
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BAS checks out normal per the service manual. And as you say I can't figure a mechanism for how the BAS would interrupt the coils and the injectors at a very specific RPM and throttle setting.
 
Uncle Phil said:
Gremlins? I know you've tried about everything except cremation of the thing! If it's 'firing' at the wrong time, maybe a stretched timing chain or worn gears(on the 11 I guess it would be a belt)? Just idle speculation on my part since you've already covered the obvious.
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The scope tracings we produced show the timing is stable but both the coils and the injectors fail to "fire" when this happens. Rather an a mistimed spark/fuel pulse, it's just entirely skips cycles for as long as you can preserve the exact condtions.
 
Then I would think it has to be a problem with the 'processor' or the connections from the 'processor', but then you've replaced all of that. It almost sounds like the 'mapping' has a 'blank' place in it. If it were a desktop computer, I'd say it was having bit failures in the memory - sort of like 'electronic' Alzheimer's.
 
So when they fail to fire do the injectors and coil lose the signal to fire from the ecm or do they lose the voltage from the bank angle sensor relay?
 
I was just thinking some more about this. I'm trying to go down a path of diagnostic based on what evidence you have gathered. I was going to say test the supply side of the injectors and coils for dropout when miss occurs, but because you say the tach drops to zero also has me thinking it may be a ecm input problem as I doubt the supply circuit is the same for just the tach and the coils/injectors (although I could be wrong have not looked at diagram). So that leads us to the ECM - nope, you swapped that already. So then the crank sensor or it's wiring - nope you swapped all that too. It would be really nice if you were able to backprobe the crank sensor lines at the ECM and scope that signal for observation when misfire occurs. What I'm left with is a question regarding the mechanical condition of the tone ring on the crank for the crank sensor. Maybe it's loose or has damage and only vibrates at some sort of resonant frequency at certain rpm? If you have already checked into this please forgive me there are too many posts to go back through....
 
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