electrical/engine whack

[Filmcamera]

The other day as I was out on a ride with my wife the tachometer started playing up and then died completely.  When I got home I took off the instrument cluster, cleaned all the pins and reconnected it.  The tacho was working again so I thought the problem was fixed.  Then yesterday I started the engine to warm the bike up a bit.  After a couple of minutes I revved up to about 4000 and the engine made a funny clunk sound and died.  It would then not restart for a few minutes.  Eventually it did restart but ran very badly and when it was running the tacho was out again.  I left it for a while and tried again today. Now she starts fine and runs pretty good but the tacho is still out and when I hold a constant throttle the revs vary up and down wildly.  I have attached a video showing what I mean.


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Any ideas?

[The Mighty Gryphon]

I think the tach signal comes from the HES and a wonky spark could be causing the erratic engine.  Since it doesn't appear to be heat related, I would check the connector for the HES harness since the HES are probably okay.  After that, check the ignition signal input at the motronic.   A good cleaning and reconnect of the big plug may be in order.

[Scott_]

It sounds like my 1100 did a few years ago when I lost 2 cyl....My case was 2 burned valves, yours could be electrical in nature.

With your tach acting up, it's possible you could have lost the coil ground (output)point from the ECU as the tach gets it's signal from the same coil terminal. At the same time with no coil ground, no fire on 2 cylinders(2&3).

Check for spark on plugs 2 & 3.

If no spark, there are several potential possibilities.
1, grounded wire between coil and ECU plug.
2, bad coil causing a ground on the line to the ECU.
3, bad ECU "output" point for the coil/tach ground such that it is staying grounded and thus no tach and no spark.
4, grounded wire between tach(cluster) and ECU plug.
5, bad HES sensor not firing the ECU "output".
6, some dirty connections..
 

[Filmcamera]

Thanks for the replies, lots of stuff to work on there.


The coils do seem to have something to do with it but there again so does the cutch ..


two more videos








I will give the main ECU plug a good clean tomorrow and also go over the earths etc and also check the spark in all the cylinders.  It is a odd one for sure.

[Laitch]

Disengaging the clutch demonstrates that the ignition control system can't respond to a sudden change in load—similar to what is happening when you twist the throttle—because the ignition coil path is faulty. The fault is likely in the coil grounding or other connections, as Scott_ has indicated in part of his response. Are those the original coils? I'd center exploration on them first since you can reproduce a fault by manipulating them.

You get high marks for video presentation, and diagnosis by palpation. :clap:

[The Mighty Gryphon]

Don't forget the connector between the HES and the engine harness.  It's under the tank, and often overlooked.

[Filmcamera]

OK I will make sure to give that a once over and clean tomorrow as well

[Filmcamera]

I took the coils off the bike today and gave everything a good clean.  When I put it back together the bike wouldn't start.  I double checked everything and tried again. This time it would not start AND the pump did activate.  More wiggling and it fired up perfectly with even the tachometer working.  A few more wiggles and it went back and forth but now seems to have settled into running perfectly again, but for how long?


So it seems the issue is in the loom.  I have had issues before with that, I had a injector stop working every now and then. 


Here are a couple of photos of the loom and how it is routed, it seems wrong somehow and very cramped.











Does that look right?


Also can anyone suggest where I might start looking in the loom? It seems unlikely one single wire would cause all the issues I have had - tachometer not working, cylinders not firing, ignition not working right etc.


I am guessing it is probably the injector portion of the loom but am very open to ideas. I hate the idea of digging that deep in there, I am more likely to make things worse than better.

[Scott_]

Doh,,, it just hit me, something else to check out that I keep forgetting about on those K1004v's is that darn ignition amplifier....
Not uncommon for the heatsink past to dry out and cause ignition issues...
The wire for the Tach terminates in the connector of the ignition amp along with the wire to the coil for #2 & #3.

[Filmcamera]

Thanks for the info about the tach feed.


I actually replaced the heat sink paste on the ignition amplifier last year so hopefully it is ok but I will double check it.

[billday]

What is it that you're touching under the coils in the video?

[Filmcamera]

It was the coil itself, I was pushing it up.  In the end though i think the coil was touching the loom and that was what was making the engine splutter etc.


After taking everything off and putting it back on again I found that just wiggling the loom cause/fixed the issue without touching the coil at all

[Scott_]

Well, it sounds like you are getting closer to the resolution.... some bad wiring in the loom, or at least some bad connections at the end of the loom.

[Filmcamera]

Today I got round to totally taking off the half of the loom with the EUC connection, injectors, coils etc.


When disconnecting the big main plug under the tank it came off very very easily, too easily.  Anyway I cleaned everything up and before taking a knife to the pretty loom I though I would reconnect it all again.  It seems fine now, I wiggled and tugged and moved it around a ton and the engine stayed exactly the same.


So it seems the main plug was loose, which thinking about it makes some sense because


1. There were it seemed too many symptoms and issues to be one bad wire
2. I had just been working around there after I had electrical the short issue a month or so ago.
3. It tended to cut out when the revs got higher meaning there was more vibration and that connection is directly over the engine.


Anyway I am going to take it for a ride tomorrow and see how it goes, I just have to put all the damn plastic back on first! Sigh, I do wish for a naked bike sometimes...