Ignition Problem?

Joined
Mar 13, 2012
Messages
5,046
Location
soCal
Bike
'97 ST1100
STOC #
687
But, like the guy with two clocks who is no longer certain of the time... :D


Enjoy your new toy.
I'll have to go into the lab at work and see what we have there, something at least 5.5 or 6.5 digits, so I should be able to see where it is calibration wise. The guy claimed it was calibrated and taken out of a working environment when they shut down several years ago, so he thinks it should still be fairly accurate. In other words, they didn't just throw it out the door because it wasn't working and he happened to be there to pick it from the trash. So that's encouraging, but I don't really need anything this accurate in the first place. I'm an instrumentation junkie, for $50 I couldn't say no. And he said if I'm not happy with it he would take it back, so he seems pretty sure its in good shape.
 

ST_Jim

In the Hotel California...
Joined
Dec 8, 2004
Messages
581
Location
Simi Valley, CA
Bike
2004 ST1300ABS
STOC #
4829
why do you need 6.5 digits? Those also cost a LOT more than the 3478. I can't come up with a reason to even need 5.5 digits, but for $40 if its even close to being in calibration it would be worth it. If I lived closer I'd be a buyer, but don't feel like riding 200 miles each way to pick it up.

It's not so much a need, as a want. I've got a 34401 sitting in my cube at work. I like it, know it's idiosyncrasies, has a 10Gohm input impedance mode, vs. an old, irreparable if it breaks, 3478.

But I went with a Fluke 87V for my last e-tool purchase, to replace my 30 y.o. Fluke 8060 with the bad LCD.
 

ST_Jim

In the Hotel California...
Joined
Dec 8, 2004
Messages
581
Location
Simi Valley, CA
Bike
2004 ST1300ABS
STOC #
4829
While looking over the list of what you have done to date it occurred to me that everything that has been tried is mostly related either to electrical or drive-ability/emissions. Have you considered the possibility that there maybe a mechanical problem that is manifesting itself as an ignition/fuel problem? As an example of what I mean older cars that had distributors with worn distributor shaft bushings often exhibited what appeared as ignition problems as they misfired, pinged, lacked power, etc. because the ignition timing was jumping all over the place. These were the symptoms however. The cause of the problem was mechanical- the worn distributor bushings. Unfortunately I do not have a brilliant idea to offer you of a mechanical anomaly that would cause your specific issue. If you haven't already eliminated everything mechanical however, it might be worth giving it some consideration.

I had an Opel Kadett years ago that ran ratty. It wasn't the distributor bushings, but the breaker plate bearing had worn an oval into the plate. So you'd bump the throttle, it would try to advance, but the dwell angle on the points would jump all over the place. Fortunately I was able to buy just the breaker plate rather than the whole distributor.

So that kind of thing crossed my mind a little. Like say a cam or crank sensor. It produces an output with a signal proportional to it's proximity to the metal notches in the cam or crank. If the cam bearings are worn to give a little more wobble in the shaft at certain RPMs, maybe the sensor output changes. And the ECM input, through a bad design, is sensitive to very slight amplitude variations that can't be seen easily on a noisy scope view. The signal is there but the ECM isn't detecting it correctly and cuts out. Then Honda quietly fixes it in later generations, with the new ECM.

But Jeff's in the unfortunate position of having lots of miles and a salvage title, which make the dollar value of the bike low. And he's already thrown lots of parts at it in a guessing game, and untold number of man hours, and he's just sick of it. At this point he could do a whole engine swap, yet not be confident it would fix the problem.

Maybe we should take up a collection to buy it and put him out of his misery. Or maybe he should donate as a door prize at WeSTOC - except no one that knew of his situation would take it, unless they want to cannibalize that Racetech suspension!
:crackup
 
Joined
Jan 8, 2011
Messages
7,066
Location
Arizona
Bike
2007 Honda ST1300A
My suggestion.....when he returns the speed sensor to Bob.....just leave the bike attached to it :rolleyes:
 

Andrew Shadow

Site Supporter
Joined
Jan 28, 2012
Messages
5,070
Location
Montreal
Bike
2009 ST1300A9
If the cam bearings are worn to give a little more wobble in the shaft at certain RPMs, maybe the sensor output changes.
That is exactly the kind of mechanical defect I was thinking of when I wrote my comment- I actually thought about worn cam/crank bearings affecting position sensor inputs. Jeff received good input signals from the crank and cam sensors when he put the bike on a scope but are the inputs happening exactly when the ECM is expecting to see them at the RPM when he has the mis-fire? I have no oscilloscope experience so I don't even know if you can tell that from a scope reading. If you can then the question is are they off enough to cause the ECM to momentarily halt ignition and injector outputs in protest? Is this reaction even part of the ECM software?

What I was actually hoping for when I referenced the possibility of the root-cause being due to a mechanical defect is that it might spark an Uh-huh moment in someone who might then have a viable suggestion for Jeff of where to look and what to check. This assumes of course that Jeff has not already considered and checked the mechanical possibilities- I suspect that he has as he has been fighting this battle for a while now.
 
OP
OP
wjbertrand

wjbertrand

Ventura Highway
Joined
Feb 8, 2005
Messages
4,407
Location
Ventura, CA
Since the output from the cam and crank sensors remain perfectly stable when the stumble occurs, I don't see how they could cause the problem. These are simple pulse generators unlike a Hall effect sensor, so they are going to produce these pulses anytime the crank and cam are rotating. They don't even depend on a battery/electrical source. If the ECM, is somehow not expecting this signal then there must be some modification of the signal downstream either before reaching the ECM or within the ECM itself. Mechanically speaking there's no radial play in the right cam bearings to which the cam sensor pulse ring is attached. Don't know how to check crank play, but if that were a problem I'd expect some funny noises and erratic sensor output, which is not the case.


Sent from my iPhone using Tapatalk Pro
 

Andrew Shadow

Site Supporter
Joined
Jan 28, 2012
Messages
5,070
Location
Montreal
Bike
2009 ST1300A9
Just for argument sake what about if the sensors are generating a correct pulse signal but not at the correct time? i.e. loose bearings, loose timing chain, etc. that causes the signal to be generated an amount of time before or after when the ECM is expecting to see that signal for the conditions at that moment. If that signal was far enough out of the parameters that the ECM is expecting could it cause the ECM to react erratically? Speculation without knowing how the ECM software is designed to react to such a variance.

Grasping at straws I know. I wish that I had a revelation that would actually help you solve this but when thinking about it I can't come up with anything that you haven't already tried.
 
Joined
Sep 10, 2011
Messages
2,210
Location
West Michigan
Bike
'98 ST1100
STOC #
8470
OK, I'll accept your challenge : If the ECM knew when to expect a signal from the camshaft & crank position sensors, then they wouldn't be needed. I agree you are grasping at straws ( no offence intended ). This is one weird problem, but something is causing it.

Like I said in a previous post, I would put a scope on the +12 volt wire feeding the ECM ( same as the Black/White wire at the Service Check connector - that's convenient ) . My pet theory is that some component on the ECM +12 volt line is vibrating at that particular RPM ( frequency ) and intermittently shorting out the +12 volts. To the ECM, this would be like turning off the ignition switch. Then when the +12 volts came back, the bike would again run normally. It would act as if the Run/Stop switch was changing positions really fast at that one RPM. An intermittent ground at the ECM may cause the same symptom. Connecting a wire from the chassis to the Green/Orange wire at the Service Check connector would rule out a bad ground.
 
Joined
Mar 13, 2012
Messages
5,046
Location
soCal
Bike
'97 ST1100
STOC #
687
OK, I'll accept your challenge : If the ECM knew when to expect a signal from the camshaft & crank position sensors, then they wouldn't be needed. I agree you are grasping at straws ( no offence intended ). This is one weird problem, but something is causing it.

Like I said in a previous post, I would put a scope on the +12 volt wire feeding the ECM ( same as the Black/White wire at the Service Check connector - that's convenient ) . My pet theory is that some component on the ECM +12 volt line is vibrating at that particular RPM ( frequency ) and intermittently shorting out the +12 volts. To the ECM, this would be like turning off the ignition switch. Then when the +12 volts came back, the bike would again run normally. It would act as if the Run/Stop switch was changing positions really fast at that one RPM. An intermittent ground at the ECM may cause the same symptom. Connecting a wire from the chassis to the Green/Orange wire at the Service Check connector would rule out a bad ground.
for those playing along at home, the scope traces are in post #215.

The part of the waveform that caught my attention way back when is the fact that both dropouts that are captured on the trace start at exactly the point in the ignition pulse trace, which would seem to suggest its receiving some kind of timed rogue signal as opposed to a random short. The fact that it recovers at exactly the same point in the ignition cycle also suggests that whatever causes the dropout, the ECU seems to respond with exactly the same behavior each time, so it seems to be doing something it thinks it should be doing as opposed to just turning off for a random period of time due to power loss.

But since we know nothing about the theory of operation on the ECU, its hard to make any claims. I suggested methodically tracing each of the other wires to the ECU until something else was found that aligned with the start of the dropout period, which could then hopefully be traced back to its source to try to get an idea what might be happening that triggers the dropouts.
 

Andrew Shadow

Site Supporter
Joined
Jan 28, 2012
Messages
5,070
Location
Montreal
Bike
2009 ST1300A9
OK, I'll accept your challenge : If the ECM knew when to expect a signal from the camshaft & crank position sensors, then they wouldn't be needed. I agree you are grasping at straws ( no offence intended ). This is one weird problem, but something is causing it.
I did not mean that it was hard coded and therefore the input signal was not needed. Many years ago when I worked on car injection systems the programing included parameters that things were supposed to operate within. If they didn't a fault was triggered. i.e. At 60 M.P.H. under a given atmospheric condition the ECM expected to see a TPS value, RPM value, MAF value, transmission gear position value, MAP value, etc., within a pre-programmed range of acceptable values. The ECM constantly monitored these values and adjusted various outputs to keep the system operating as close as possible to what the programmers considered optimal. If you were maintaining that speed under those conditions and any of those values were far enough out of whack that the ECM could no longer compensate (e.g. the TPS position sensor was reporting that the throttle was in a position that is consistent with doing an RPM of much higher than what the other sensors are reporting the actual RPM to be) a fault code would be triggered. If these conditions continued the ECM would turn on the check engine light and set a trouble code. Under certain conditions if the ECM could not compensate for the variance it would freak out and go in to back-up mode and turn on the check engine light in protest. Would anything similar to this cause a momentary and specific loss in ignition and injection function? Could a mechanical variance cause a sensor to be far enough out of whack to cause a momentary and specific loss in ignition and injection function as you are seeing? If yes you would certainly expect to see a trouble code related to that sensor system. I cannot think of a scenario where it would but as I have already said I know very little about the ST1300 injection system. I really wish that I did and that I could come up with some fantastic suggestion that would actually help you because I can only imagine how frustrated you must be.
 
Joined
Mar 13, 2012
Messages
5,046
Location
soCal
Bike
'97 ST1100
STOC #
687
I assume when Jeff traced the crank and cam position sensors in the scope trace, and they were normal, that he had the scope probes at the sensor, not at the ECU input. It is possible that somewhere along the path that signal is getting corrupted before entering the ECU, but since he replaced the entire wiring harness the chance that its a bad wire is very slim. However, perhaps there's some crosstalk on the wires at that RPM, and that's what is causing the problem. That's why I suggested probing the inputs directly at the ECU (although we don't know which wires are inputs and which are outputs at this point) to see if there's any other signal correlated in time with the cutout episodes. Its a lot more guesswork, and Jeff is fed up with it, so someone else will have to take up the fight.
 
Joined
Sep 10, 2011
Messages
2,210
Location
West Michigan
Bike
'98 ST1100
STOC #
8470
I took closer look at the traces on page 215, and I have to say now my theory about losing the +12 volts is probably wrong. Still may be a ground problem, tho.

When the misfire occurs, on the traces, the coil & F.I. line stay high ( +12 volts ). The problem looks like the ECM isn't pulling those two lines low, to cause a spark and to turn the F.I.'s on.

OK, so why ? The ECM is failing to do it's job for some reason.
 
Joined
Mar 13, 2012
Messages
5,046
Location
soCal
Bike
'97 ST1100
STOC #
687
Jim,

I'm of the other opinion, I think the ECU is doing exactly what it wants to do, but is getting a rogue input at various times.

take a closer look at the pulses on the cyan channel whenever the misfire occurs. You'll notice that the last ignition pulse is always shorter than the normal ignition pulses, and always by the same amount. If I had to guess I'd say they're about 75% of the normal duration. We see this pattern several times in the traces, so its very unlikely its a coincidence, but I have no idea what it means either. Its that consistent timing that makes me think the ECU is doing something on purpose, based on something its seeing as an input, which is consistent with the fact that three different ECUs all produced the same misfire. If it were a power/ground failure it would likely show a more random scope trace, but I can't say that for sure.

without seeing all the other ECU inputs to give a clue to what might be triggering it, guessing at it isn't going to get us anywhere.
 
Joined
Sep 10, 2011
Messages
2,210
Location
West Michigan
Bike
'98 ST1100
STOC #
8470
Doug : I agree. The ECM is doing exactly what it is programmed to do, but not what it should normally be doing, if that makes sense.

I see what you said about the SECOND coil trace pulse being a bit less wide than normal. But look at the top coil trace. When the second trace is shorter, the top trace never goes low, but there seems to be some ringing, only. It looks to me like what is happening at the top coil is causing the signal at the second coil to terminate. So why isn't the top coil being pulled low by the ECM ? Since the ECM was swapped, we know it's not a faulty ECM.

It looks like the ECM may attempt to pull the line low, but when no primary coil current is detected, the cycle is terminated for both coils. That may be why the second trace goes back high prematurely at that point.

And the interesting thing is that there is no trouble code for "no coil current" or "open coil". So even if a fault is detected, there isn't a code set for it.

So, here is a question for Jeff :

When the second set of coils were swapped in, where only the individual coils swapped, or the entire coil assembly including the wires going to the coils and the two 2-pin connectors ? If only the coils, there could be an intermittent open in the top coil negative wire ( in the traces ) that is occurring at only a certain frequency ( RPM ).


There is a report of a ST1100 with a similar problem.
See : http://koczarski.com/mmartin/Intermittent.htm

"A close inspection of the harness revealed a break near the connector to the coil , but inside the insulation."

BTW, I had an old Moto Guzzi with a Dyna ignition that had a miss at only certain RPM's. The problem turned out to be a bad solder joint inside the pulse detector between the Hall Effect device lead and the wire that was suppose to be soldered to it. It was fairly easy to troubleshoot down to the pulse detector by switching wires around for/between the two cylinders. When I went to replace the Hall Effect detector, I found the bad connection. I simply resoldered it ( didn't replace the sensor ) and it ran great after that repair. The connection was buried in epoxy.


At this point, just for the heck of it, if an intermittent open in one of the coils wires isn't found, then besides disconnecting the instrument cluster connector, ( that was suggested before by a poster ) I would connect a 0.47 uF cap at the Service Check connector between the +12 volt pin and Ground pin, just for S&G's.
 
Last edited:
OP
OP
wjbertrand

wjbertrand

Ventura Highway
Joined
Feb 8, 2005
Messages
4,407
Location
Ventura, CA
IT'S FIXED - at least as far as I'm concerned. STat's new owner, a navy mechanic, just rode off on her. He's got the whole service history and it didn't phase him at all. I told him to drop me a note if he solves the problem. Well, it's over, I gave up but it's a load off.


Sent from my iPhone using Tapatalk Pro
 

DavidR8

Site Supporter
Joined
May 31, 2017
Messages
1,220
Location
Vancouver Island, British Columbia
Bike
2013 BMW R1200RT
STOC #
8968
IT'S FIXED - at least as far as I'm concerned. STat's new owner, a navy mechanic, just rode off on her. He's got the whole service history and it didn't phase him at all. I told him to drop me a note if he solves the problem. Well, it's over, I gave up but it's a load off.


Sent from my iPhone using Tapatalk Pro
Well done.
What's next? Summer is just around the corner!


Sent from my iPhone using Tapatalk
 

Mellow

Joe
Admin
Joined
Dec 1, 2004
Messages
18,819
Age
60
Bike
'21 BMW R1250RT
2024 Miles
000540
Sometimes ya gotta just move on... Hopefully, the new owner will figure it out, I know we are all stumped here but a new set of eyes will many times do the trick.
 
Top Bottom