Jumpy when holding speed

[br0kestudent]

Hi guys, this is a weird one and I don't know what could be causing it.

The bike itself - FZ6N 2005, 57K KM, stock.

Whenever I got for more than 30/40min rides and the bike gets nice and toasty, holding a speed at any gear/rpm becomes a nightmare. If I barely hold the throttle, I'm talking edging the line between open/closed, the bike lurches after some sort of flat spot, like as if I'm twitching it myself.

As part of my diagnosis and fixes done I thought perhaps chain, sparks or filters could be doing this as it felt like either the chain was slipping or it was misfiring.

After new spark plugs, chain adjustment and new air filter it still does this. It has no problem when accelerating/decelerating.

About a week ago, I drove 450/500km in an day as I went to meet my girlfriend on the other side of the country (Ireland) to drive back with her (to the other side) after she got a new bike.

As we probably didn't do much more than 100km/h and stuck to 60/70 I think the bike didn't like this very much as it threw error code 33 literally the day after while I was doing some town riding.

The bike then ran very very sluggish, becoming very low in power and would die if not revved when at a standstill. This kinda 'fixed itself' the day after and didn't show for another few days.

Finally, it showed up again as I was riding up to meet my girlfriend, and it started being very lurchy and rough. I was too far from home to go back and too far from hers to suffer with this. I noticed it would 'fix' itself a little if I gave it more revs and after some aggressive riding the error and roughness went away - I admit now this was very stupid to do as I could have potentially done the engine in.

I guess my question is, is the lurchiness normal while opening the throttle a tiny bit and holding it or is something banjaxed.

Thanks everyone

 

[Gary in NJ]

Based on your description, and the fact that you are getting error code 33, you have a failed ignition coil (the coil for 1&4). Does this problem only appear after the bike is warmed up? That’s another tell tail sign. Before replacing the coil, ensure that you are getting 12+ volts to the lead. You could also check its resistance, best to check when it’s hot (use a heat gun).

 

[br0kestudent]

Hi sorry for the late reply, when you mean 12v to the lead is that the connector to the ignition coil? And if I'm checking resistance what am I looking for?

Spot on, it's generally fine for the first 30/40mins then it can start acting up.

 

[br0kestudent]

Hi sorry for the late reply, when you mean 12v to the lead is that the connector to the ignition coil? And if I'm checking resistance what am I looking for?

Spot on, it's generally fine for the first 30/40mins then it can start acting up.

Update, coil for 1/4 is showing 12v across the red line and no visible damage to the coil itself and on coil 4 (couldn't get to 1 as don't have time right now to take out air box etc) the spark is nice and bright when using diag (option 30) to get it to test the coil/lead/spark

Update 2: I forgot to check resistances (bah) after I heated up the coil but I reproduced the issue after about two minutes of on/off with the heat gun. Instead of taking the usual 40mins of riding, it appeared immediately. I turned the bike over put it into first gear and it flashed the engine light, 33 and 2 cylinders weren't firing.

 

[Gary in NJ]

Coils 1&4 are common as are 2&3.

The Primary coil resistance should be 1.53 to 2.07 Ω
The Secondary coil resistance should be 12.0 to 18.0 kΩ (Note the K)

The resistance in the coils increases as they get warmer...that's why they work well on a cold start, but fail when the bike warms up (they get heat soaked from the engine heat).

 

[br0kestudent]

Coils 1&4 are common as are 2&3.

The Primary coil resistance should be 1.53 to 2.07 Ω
The Secondary coil resistance should be 12.0 to 18.0 kΩ (Note the K)

The resistance in the coils increases as they get warmer...that's why they work well on a cold start, but fail when the bike warms up (they get heat soaked from the engine heat).

Yeah that makes sense, so a replacement coil is the solution here then? If so, am I good to get fz6 coils or should I be looking at aftermarket or different model/year with better heat resistance

 

[Gary in NJ]

I’d look for a used coil. Stick with OEM as aftermarket units will be Chinese reproductions.

 

[Motogiro]

Also keep in mind a bad switching transistor in the ECU can cause the same error codes. Check your ECU plug for a good clean connection at the pins.
If this seems to follow ambient temperature change, it's likely the coil.

 

[br0kestudent]

Gotcha. Thanks lads, fwiw I did actually check the ECU plug (not ECU itself) for the pins and they were all nice and silver plated. No signs of corrosion etc. Not that it's a definite guarantee the ECU isn't the issue but if it was id expect some signs of wear there

 

[br0kestudent]

Replaced the coil, it drove grand for about an hour. Pulled over for maybe a minute, started her up again and error 33 popped up. Left it for another few, turned it off still there, revved it a couple of times, took off and it just disappeared after shifting into second. Didn't appear again for the rest of the journey.

 

[Motogiro]

Replaced the coil, it drove grand for about an hour. Pulled over for maybe a minute, started her up again and error 33 popped up. Left it for another few, turned it off still there, revved it a couple of times, took off and it just disappeared after shifting into second. Didn't appear again for the rest of the journey.

In reference to the ECU, there are small delicate pins on that plug. The last pins that are colored, orange with a black tracer and grey with a black tracer at the plug are your coil pack grounds. These ground paths are operated by an internal switching transistor for each coil pack. Be sure the pins are present and clean on both halves of the ECU connection. It has also been a problem in the past with a member that had road salt contamination in that area. Cold water flush and immediate dry with with compressed air. Reseal with dielectric grease.

 

[br0kestudent]

I'll get a better look at the ECU pins tomorrow morning, it's pitch black here now agh. I'll see if I can get a can of compressed air/dielectric grease, provided I noticed any corrosion to the ECU pins. Thanks for the advice

 

[TownsendsFJR1300]

Cliff, your thoughts on using say a .005" trimmed down (the sides) feeler gauge
to "feel" the resistance (or lack of) on the female end of the connection?

I know they make a specific tool for that (various sizes of course).


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[Motogiro]

Cliff, your thoughts on using say a .005" trimmed down (the sides) feeler gauge
to "feel" the resistance (or lack of) on the female end of the connection?

I know they make a specific tool for that (various sizes of course).


.

Sorry Scott. I'm not understanding about the feeling gauge.

 

[TownsendsFJR1300]

Sorry Scott. I'm not understanding about the feeling gauge.

For the very small female end of a connector. Sometimes they get loose and don't have a good connection
with it's male counter part.

Here ya go:

https://checkitprobes.com/


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[br0kestudent]

I have checked the ECU, apart from a little dust on the outer edge (not near the pins) it was as clean as could be. No bent pins, no corrosion.. nothing. It's just the intermittency of this issue that makes it confusing to me, and from my last ride I wouldn't even say it was because it was hot like it was before - I will test this when I'm back from my girlfriends though (heat gun like before).

I don't think I'm understanding right about the feeler gauge either, what part am I using this on? And if it's the coils, would it be the lead end?

 

[TownsendsFJR1300]

The link for the tool above, checks how tight the pins are to each other when the connector is assembled.

If there's a loose female pin, not holding the male tight, it'd be a bad connection...


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[br0kestudent]

The pins on the ECU? What's the difference between me sticking on a MTF wire on the connectors and probing those, as I'm in Ireland and I don't think it's necessary to spend money on specialist tools like so.

Update: Fun fact I found, pushing down on the ECU connector, where the coil wires for pack 1&4 are plugged in, fixed the issue and if I pushed it down elsewhere it started the issue. So I'm thinking that you're right TownsendsFJR, what's the resolution here then. How do I 'tighten' the female connector

 

[TownsendsFJR1300]

I initially mentioned trimming down a feeler gauge, not spending $100 on a special tool.

I posted the tool so Cliff and everyone else knew what I was talking about (a "drag" tool).

As for the repair, there's several companies that sells pin's, IE:

Automotive Connectors

Automotive connectors for your repair and upgrade needs. Most are OEM units direct from the manufacturers. Highest quality connectors from Japan.

www.easternbeaver.com

https://www.cycleterminal.com/

There may be some tips / short cuts about a repair, so do a search or someone may chime in.
Might be as simple as a very, very slight pinch on the connector.



Quote:

"Update: Fun fact I found, pushing down on the ECU connector, where the coil wires for pack 1&4 are plugged in, fixed the issue and if I pushed it down elsewhere it started the issue."

End quote.

Sounds like you found the issue!!




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[tuning-forks]

Also, oxidization can be invisible. Even though it looked good, a shot of electronic contact cleaner might be in order (non-lubricant type so no residue left behind).