Low RPM Sputtering

[TownsendsFJR1300]

I personally wouldn't trust those boots..

With that said, if your running out of adjustment, open up (counter clockwise) the base screw
to about 7/8ths a turn out from lightly seated.

That should give you more room for adjustment. As stated earlier, don't worry about the the HG

The "stop screw" you mention is not a "stop Screw". It's for syncing the two throttle, separate throttle bodies together.

 

[trepetti]

Hi all,

I have problem with sputtering at low RPM (idle rpm). I read a lot of topics about this problem but i am at the end with ideas where can be problem.

It is FZ6 S2 2008 with stock exhaust

I did "bigger" service in March (1 300 km ago)
- new spark plugs (NGK CR9EK)
- new 1 cable from coil to spark plug
- new oil + filter.

After 1 300 km started my problem with sputtering at low rpm.

So, i started inspect:
- i dissasbled spark plugs with coils - I measured everything with multimeter. Both Coils and cables have resistance according service manual. - Spark plugs have resistance as stated by the manufacturer. Everything good seems to be here.
- I took out fuel pump. Filter was little dirty (I cleaned this filter 1 year ago), but I don't think there will be a problem, because problem is only in low rpm.
- I tried measure TPS values. Values were 20 and 101. I adjusted TPS to 17-98. But resistance was not according service manual, every resistance was out of specs with big differences between my values and values in service manual.
- Okay, I bought new TPS and adjust on 18-98.
- Fuel injectors are tested and cleaned - there is no problem.
- Idle speed was adjusted on 1200 - 1300 rpm
- I checked (only by eye) every hose, without problems and damages.
- I checked every point in Diag mode - solenoid valve, coils (I listened them), injector relays...
- I checked temperature on exhaust pipes. Every pipe is hot.

After changed TPS sensor and cleaned injectors bike better responds on gas. However, problem still persists...

In high rpm bike runs without problems!!


I have ordered gauges for TB sync, this is my last idea where could be the problem.


Have anybody any idea or had anybody the same problem?


Thanky you.

I reread parts of this thread this morning and I think we may have missed something that may be important.

Early on in the thread it is determined that 1 cylinder was cooler than the other 3. And it seemed like the problem might be an intermittent misfire, not a completely dead cylinder. And it was also mentioned in the OP's first post that 1 spark wire was replaced.

I recall years ago reading how the wires are attached to the coil with some sort of adhesive. Yamaha does not sell replacement wires, so this is not a recommended repair.

Also, although it was suggested, I do not think the OP swapped coils or wires to see if the problem moved. The OP did swap the spark plugs between 2 cylinders, but that is not what was suggested.

So here we are with the valve cover off, checking carbon on the valves, replacing boots and we still don't know what the problem is.

If is were me, I would put things back together and isolate the problem. Is it different exhaust temperatures? If so, swap the coils and see if the problem moves. Pay special to attention to the coil with the new wire. This item is now my #1 suspect......

 

[vrtulnik]

I personally wouldn't trust those boots..

With that said, if your running out of adjustment, open up (counter clockwise) the base screw
to about 7/8ths a turn out from lightly seated.

That should give you more room for adjustment. As stated earlier, don't worry about the the HG

The "stop screw" you mention is not a "stop Screw". It's for syncing the two throttle, separate throttle bodies together.

View attachment 74446

I meant this screw. (blue circle).

I reread parts of this thread this morning and I think we may have missed something that may be important.

Early on in the thread it is determined that 1 cylinder was cooler than the other 3. And it seemed like the problem might be an intermittent misfire, not a completely dead cylinder. And it was also mentioned in the OP's first post that 1 spark wire was replaced.

I recall years ago reading how the wires are attached to the coil with some sort of adhesive. Yamaha does not sell replacement wires, so this is not a recommended repair.

Also, although it was suggested, I do not think the OP swapped coils or wires to see if the problem moved. The OP did swap the spark plugs between 2 cylinders, but that is not what was suggested.

So here we are with the valve cover off, checking carbon on the valves, replacing boots and we still don't know what the problem is.

If is were me, I would put things back together and isolate the problem. Is it different exhaust temperatures? If so, swap the coils and see if the problem moves. Pay special to attention to the coil with the new wire. This item is now my #1 suspect......

1 cylinder cooler: It was bad measure, because I first measured temps from left side of bike. I measured temp of #1 cylinder from outer side, and there was lower temp than #2 and #3 pipes and #4 from inner side. When I went measure from right side of bike in the same way, I had the same temp on all cylinders.
I swaped coils and temps were the same.

Yes, 1 wire was replaced, because was damaged from fan. It is #3 cylinder wire. I had out all coils, spark plugs, caps and measured resistance - Everything is in spec.

During higher rpm running good, smoothly, without sputtering. Problem is during start-up on 1st gear, but not always. Idle speed is not stabil.

Problem started 2 months (after 1 000km) after: exhange spark plugs, oil, #3 coil wire, removed air box and battery, radiator.

Today, when I mounted air box, it seemed that there was problem - clamps on air box boots did not fit correctly. Idle speed was stabil. I turned off bike and started up again - problem persists...


May be old battery. I tested it only by the Voltmeter. When Bike is off, battery has 12.7 V.

Again, in higher rpm during drive motor runs okay without sputtering. Problem is in idle (1 300 rpm) and lower rpm - until 2000 - 3000.

 

[trepetti]

I meant this screw. (blue circle).

View attachment 74447






1 cylinder cooler: It was bad measure, because I first measured temps from left side of bike. I measured temp of #1 cylinder from outer side, and there was lower temp than #2 and #3 pipes and #4 from inner side. When I went measure from right side of bike in the same way, I had the same temp on all cylinders.
I swaped coils and temps were the same.

Yes, 1 wire was replaced, because was damaged from fan. It is #3 cylinder wire. I had out all coils, spark plugs, caps and measured resistance - Everything is in spec.

During higher rpm running good, smoothly, without sputtering. Problem is during start-up on 1st gear, but not always. Idle speed is not stabil.

Problem started 2 months (after 1 000km) after: exhange spark plugs, oil, #3 coil wire, removed air box and battery, radiator.

Today, when I mounted air box, it seemed that there was problem - clamps on air box boots did not fit correctly. Idle speed was stabil. I turned off bike and started up again - problem persists...


May be old battery. I tested it only by the Voltmeter. When Bike is off, battery has 12.7 V.

Again, in higher rpm during drive motor runs okay without sputtering. Problem is in idle (1 300 rpm) and lower rpm - until 2000 - 3000.

Would you agree that it is an intermittent problem? Like you said, bike runs ok, turn it off and problem returns. It is important that all your testing be done when the problem is happening. You mention the 2 times you measured temperatures of the exhaust. 1 time there was a difference and the other time they were the same. Was the bike sputtering during both tests?.

As for the battery, I am guessing that this is not a problem. But the problem is we are all guessing.

 

[vrtulnik]

Would you agree that it is an intermittent problem? Like you said, bike runs ok, turn it off and problem returns. It is important that all your testing be done when the problem is happening. You mention the 2 times you measured temperatures of the exhaust. 1 time there was a difference and the other time they were the same. Was the bike sputtering during both tests?.

As for the battery, I am guessing that this is not a problem. But the problem is we are all guessing.

as for measuring temps - Yes, I did measuring many times and bike was sputtering all the time.

It is hard describe this situation. I am thinking about it already 2 months. The engine does not run correctly during idle speed, idle speed is fluctuate, all the time - engine is not running smoothly (steady).

How Can I verify that one cylinder is omitting? Theoretically, when I will unplug spark plug cap from #3 cylinder (if #3 cylinder coil wire is bad), rpm should be steady. Engine sound will be different, but fluctuate idle speed should stop.

Here is video - you can hear fluctuate idle speed. When I suddenly increase rpm from idle speed (especially during drive) bike will start sputtering.

 

[TownsendsFJR1300]

Sure sounds like an ignition issue, cutting out (and then back in)...

Do you have access to to a timing light or in-line spark tester?

I would check each wire (with either tool), running, and see if your dropping spark at a coil wire one at a time..

 

[vrtulnik]

Sure sounds like an ignition issue, cutting out (and then back in)...

Do you have access to to a timing light or in-line spark tester?

I would check each wire (with either tool), running, and see if your dropping spark at a coil wire one at a time..

Do you mean this tool?

 

[TownsendsFJR1300]

The one you pictured I think would be difficult reaching down into the head, but yes in general.

This is one (I use) should work for you. The one side will reach deep in the valve cover.

Also, thinking about it, test the spark (for each cylinder) WHEN COLD, actual cranking, as that seems to be a big issue as well.

Amazon.com: Lisle 20610 Inline Spark Tester : Automotive

Buy Lisle 20610 Inline Spark Tester: Spark Plug & Ignition Tools - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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[vrtulnik]

The one you pictured I think would be difficult reaching down into the head, but yes in general.

This is one (I use) should work for you. The one side will reach deep in the valve cover.

Also, thinking about it, test the spark (for each cylinder) WHEN COLD, actual cranking, as that seems to be a big issue as well.

Amazon.com: Lisle 20610 Inline Spark Tester : Automotive

Buy Lisle 20610 Inline Spark Tester: Spark Plug & Ignition Tools - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

View attachment 74463

Thank you.

I ordered tester.




If the ignition is OK, should the bulb flash?

 

[TownsendsFJR1300]

Yes, it'll flash MUCH, MUCH brighter than a spark plug would show.
It doesn't affect the running at all, it just gives you a "visual" of ignition spark or no spark, or intermediate spark..

Should a cylinder NOT fire while running, it'll (the tool) will be very obviously "dead" / no flash.

.

 

[vrtulnik]

Yes, it'll flash MUCH, MUCH brighter than a spark plug would show.
It doesn't affect the running at all, it just gives you a "visual" of ignition spark or no spark, or intermediate spark..

Should a cylinder NOT fire while running, it'll (the tool) will be very obviously "dead" / no flash.

.

Thank you very much.

It will be hard get this tool to spark plug holes, because there is small space.

I will make video with each cylinder, just i must wait for tester.

I am thinking.. Is it possible that problem is in bad regulator, or stator and charging system?

 

[TownsendsFJR1300]

It shouldn't be a problem getting this tool down the hole.

Once hooked up, it'll be VERY visible when the coil is firing (and when it's not)

 

[trepetti]

The voltages you listed in post #10 indicate a working charging system, so you do not have a bad stator, rotor or regulator / rectifier.

I still suspect the replaced spark plug wire. If it has an intermittent connection it might still test ok for impedance. I see you tested exhaust temperature, but I think that was with the motor off.

If it is sputtering on 1 cylinder then I believe that the bad cylinder must have a different temperature than normal. If you can nail down the bad cylinder then it should be easy to identify the bad part. Why not do more temperature testing with the engine running and see if you can narrow down the problem? If you do, pay careful attention to the repaired spark plug wire to see if that is the bad one.

If we cannot narrow the problem down, all you can do is blindly replace parts until the problem goes away.

 

[vrtulnik]

The voltages you listed in post #10 indicate a working charging system, so you do not have a bad stator, rotor or regulator / rectifier.

I still suspect the replaced spark plug wire. If it has an intermittent connection it might still test ok for impedance. I see you tested exhaust temperature, but I think that was with the motor off.

No, engine was not off. I measured temps when engine was turned on.

I will try measure temps again, tomorrow.

 

[trepetti]

No, engine was not off. I measured temps when engine was turned on.

I will try measure temps again, tomorrow.

OK, I was referring to post 13 and I can hear the beep from your tested and the engine was silent.

 

[vrtulnik]

It shouldn't be a problem getting this tool down the hole.

Once hooked up, it'll be VERY visible when the coil is firing (and when it's not)

OK, I was referring to post 13 and I can hear the beep from your tested and the engine was silent.

So guys, I found problem maybe.

please see videos.

I disconected spark plug caps from #4 to #1 cylinder - engine went on three cylinder. I stoped at #2 valve. When I disconected spark plug cap on #2 cylinder, engine sound was constant. So I exchanged #2 #3 wires and than I disconected #3 cap, the same. So I found that problem is with #2 cap, wire, or coil.

When I held cap #2, I got hit. You can see spark on first video.

On second video you can see second spark betwen wire and cap.

I exchanged cap from #3 to #2 wire and the same result - spark was between wire and cap. So #2 cap should be okay.

EDIT: I read about arcing in caps and I found that should be okay, because, when caps are disconected, spark will find shortest way.

I tried it with #4 cap and there was the same arcing.

So, In evening I disassembled all wires from caps and I properly connected wires to caps. Now it is okay, engine run without sputtering.