Intermittent Misfire

I have a 2009 ST1300 owned from new. It is now showing 174,000 miles and has, this year, developed an intermittent misfire. It happens after I have spent some time, like more than 30 minutes, in heavy city traffic, stopping at junctions, moving slowly in heavy traffic, sitting at traffic lights, all at idle speed or just a whiff of throttle. I can be sitting at idle and there will be a slight "shake" from the bike and when I go to open the throttle to move off there is a very strong misfire. It feels like the bike is going on to two, three cylinders then back to two then, whoa, all four kick in then it's back to 2 or 3 again. This lasts for "some time", perhaps 3 or 4 miles at town speed and then, mysteriously clears and the bike runs as perfectly as it has since new. I have also discovered that, if I stop and switch the engine off when the misfire starts and leave the bike for 15-20 minutes, it re-starts and runs like nothing has happened. I haven't experienced this other than after city riding, out on the open road at all speeds the bike runs sweetly all day. Because the plugs were coming up to their change mileage I have fitted new ones but it doesn't appear to have improved matters. I am at a loss to think how to attack this problem, mainly because it is not present to order. There is no F1 light showing and, as I say, the bike runs as sweet a a nut otherwise. There does not appear to be any correlation between amount of fuel in the tank and the misfire occuring. There is no popping or banging in the exhaust system during the misfire. Any thoughts?

J.Murphy said:

I have a 2009 ST1300 owned from new. It is now showing 174,000 miles and has, this year, developed an intermittent misfire. It happens after I have spent some time, like more than 30 minutes, in heavy city traffic, stopping at junctions, moving slowly in heavy traffic, sitting at traffic lights, all at idle speed or just a whiff of throttle. I can be sitting at idle and there will be a slight "shake" from the bike and when I go to open the throttle to move off there is a very strong misfire. It feels like the bike is going on to two, three cylinders then back to two then, whoa, all four kick in then it's back to 2 or 3 again. This lasts for "some time", perhaps 3 or 4 miles at town speed and then, mysteriously clears and the bike runs as perfectly as it has since new. I have also discovered that, if I stop and switch the engine off when the misfire starts and leave the bike for 15-20 minutes, it re-starts and runs like nothing has happened. I haven't experienced this other than after city riding, out on the open road at all speeds the bike runs sweetly all day. Because the plugs were coming up to their change mileage I have fitted new ones but it doesn't appear to have improved matters. I am at a loss to think how to attack this problem, mainly because it is not present to order. There is no F1 light showing and, as I say, the bike runs as sweet a a nut otherwise. There does not appear to be any correlation between amount of fuel in the tank and the misfire occuring. There is no popping or banging in the exhaust system during the misfire. Any thoughts?

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May have nothing at all to do with your issue, but my "spark plug cap assembly noise supressor" had been worn down over the years and formed a crack which allowed arcing to the frame. Obviously, when the spark cane out if the crack, the spark plug wasn't firing intobthe engine. Here are some pics and a video. This is the #4 cylinder(right rear) my issue was accompanied by an intermittent electrical tick, like an igniter on a gas range.

Sent from my SM-G955U using Tapatalk
http://cloud.tapatalk.com/s/59cafe7fcfd95/20170908_213518.mp4

Mine is a 2004 ABS model

Ignition's a good possibility here.

The low-hanging fruit would be the HT leads. If there's no physical damage to the boots or wires, check that the connection between the two is good. The boots and wires are actually two separate parts with a friction-fit connection between them, so it's possible one or two has worked loose.

I note that you're in the UK, which means all of the electrical connections are subject to being interrupted by your side of the pond's special formulation of road crud. Remove and clean the ends of the HT leads that connect to the coil packs and do the same with the spade connections on the low side. There's also a pair of two-pin connectors that join the low side to the wiring harness. (I've never had to poke at mine, so I don't know where on the bike they are.)

The ignition pulses are generated by a sensor screwed into the front of the engine just above the clutch housing. That has a connector built in, and being that it's in a crud-prone area, you'll want to check and clean that, too.

--Mark

best way to check for wire leakage is to spray them down with a solution of soap and water (5% salt water is recommended but I don't like salt on aluminum) if it starts missing or get worse it the wires. Or take a test light, ground it normally then use the metal end and run it along the wires and boots while looking for spark jumping to the probe. You can also run your hand along the wires, if its a bad leak you will know it or you might feel some tingling :nuts1:.

if any of your old plug look like this, you will have to change the plug again and the wire. Its called carbon tracking, the boot gets tracked and ruins the plug. The pic looks like a crack and is but looks similar , the carbon forms a track that the spark follows

I'd be inclined to think that it is the ignition. Low revs give a clue to this, as the revs get higher, the power available to the coils increases and the spark is able to more readily able to jump across any HT lead imperfections.

Read what a similar sounding problem with my (UK) bike and what the problem was here.

Brief summary. Poor running at low revs - stuttered and backfired. No confidence n the bike pulling away without using much higher revs. Felt like riding on a bumpy road surface at normal cruising.

Much diagnosing of problem as replacement parts are expensive. But - cleaned coil contacts; cleaned sensor connector at front; replaced plugs caps; replaced leads.

Normal copper cored HT lead can be used to substitute temporarily for the OEM part.
Spark plug caps should have a resistance of 5K ohms.

More detail in the link above.

Check the ground on your coils. Not sure where it is on the ST but I've seen this problem on other bikes.

drtyrrel said:

Check the ground on your coils. Not sure where it is on the ST but I've seen this problem on other bikes.

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The coils are grounded to the chassis with metal strips under the coil mounting screws. They are prone to rusting over time. Coils are mounted to the main chassis, either side of the air filter, above the cylinder head and spark plugs. You need the middle cowl removed to get at them.

Thanks for all the input guys. It looks like faulty HT leads/plug caps are the favourite choice for causing my misfire. It sounds appealing to dive in and replace them but I'm still unsure that this could produce intermittent misfiring such as I suffer. And boy, do I suffer! I made two trips into Central London today, a total mileage of 166 miles and the misfire happened 5 times, always after a period of slow-running. When it happens the bike is almost unridable, I say "almost" but, being the riding god I am, I can cope with it - ahem!
John Heath's post was particularly illuminating and seemed to mirror what's happeing with my bike save for one important difference. I may have misunderstood the post but I gather that JH's bike ran rough at low throttle openings/low revs all the time. Mine certainly does not. It runs sweetly at all speeds until a period of low-speed riding is encountered and after about 20 minutes of this it throws a wobbler - to coin a phrase! My feeble mind tells me that if HT lead or plug cap is faulty then they are faulty, not every now and again when they feel like it?
That said, I'm rapidly approaching the point where I will change all the HT leads & plug caps just to see if it does anything and hang the logic of why it happens.
Wish me luck!

Interesting thread.

I have been experiencing a few similar issues on my '04#2.

This is the bike I bought 3.5 years ago that sat for 6 years in a shed, while broken. I have since put 30K miles on it since getting it running back in 2015. Although I took it out of commission the first of the year to try to sell, but due to a leaking waterpump (which I fixed), it didn't sell. So I've been riding it again for my commuter bike. (Yeah, it's black...

Sometimes when I start the bike, I get a click from the starter relay, but no starty... hit it a couple more times, it comes to life.
I replaced the starter switch and the starter relay (both, with used units.) It went away for a while, but it's back again. This doesn't happen every time, just sometimes.

When riding at a steady speed the bike fells like it's about to stall/lack of power, but keeps going. As soon as I'm on the throttle, it takes off, with good acceleration.

Sometimes when I'm at a stop, light or sign, when I go, sometimes it will miss/pop. To avoid this, I have to rev it up a little.

I recently replaced the spark plugs and one of the leads/sparkplug cap.

But because of the starter issue, I'm wondering if I have a ground issue.

First thing to check to see if this bike has had the ground issue fixed. Is Honda still under obligation for recalls on a 13 year old bike?

Next, I think I'll take Jfheath's suggestion of replacing all the wires and sparkplug caps. Since that one fell off, it wouldn't surprise me if they are all loose.

One other issue I have with this bike, is when I pull in the clutch (is if the kickstand is up or down) and it is in gear, it won't start, it has to be in Neutral.

J.Murphy said:

Thanks for all the input guys. It looks like faulty HT leads/plug caps are the favourite choice for causing my misfire. It sounds appealing to dive in and replace them but I'm still unsure that this could produce intermittent misfiring such as I suffer. And boy, do I suffer! I made two trips into Central London today, a total mileage of 166 miles and the misfire happened 5 times, always after a period of slow-running. When it happens the bike is almost unridable, I say "almost" but, being the riding god I am, I can cope with it - ahem!
John Heath's post was particularly illuminating and seemed to mirror what's happeing with my bike save for one important difference. I may have misunderstood the post but I gather that JH's bike ran rough at low throttle openings/low revs all the time. Mine certainly does not. It runs sweetly at all speeds until a period of low-speed riding is encountered and after about 20 minutes of this it throws a wobbler - to coin a phrase! My feeble mind tells me that if HT lead or plug cap is faulty then they are faulty, not every now and again when they feel like it?
That said, I'm rapidly approaching the point where I will change all the HT leads & plug caps just to see if it does anything and hang the logic of why it happens.
Wish me luck!

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NO NO NO under certain conditions the plugs take more kv to fire the spark has to go somewhere so it jumps at a weak point. The oldest trick in the book is to hose down the wires and boots. A cam or crank sensor will 99%of the time will not cause a misfire, a die out or no start but the computer would see loss of a signal and should through a code, do basic simple tests first . coils can hang unbolted they get their ground from the wire connector. The coil could be cracked and that's where you could be loosing spark....wet it down!!!!

drtyrrel said:

One other issue I have with this bike, is when I pull in the clutch (is if the kickstand is up or down) and it is in gear, it won't start, it has to be in Neutral.

sounds like the micro switch in your clutch lever isn't working.

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Yeah, that was my first thought too, so I replaced it...nope..didn't fix it, so I replaced the switch on the kickstand...nope it didn't either.

I really haven't taken the time on it to chase all these things down, because the other bikes have had the priority. The 2012 just came off the lift after doing a bunch of major maintenance to it. I just put the 2010 on the lift so I can chase down a clutch issue (slipping). I still have the '04#1 sitting in a shed, waiting for a new waterpump. So, as long as the '04#2 keeps running "okay" for my commute, it will probably not get fixed until the others do! 4:

If the switches are ok, it could be the connectors/wiring. But when I first read your post, I wondered if it could be the clutch diode (3 pin fuse look-alike, at the back, sideways, in one of the fuse boxes). It has the job of preventing signals from one device from interfering with the other. I haven't looked at how it would behave on the ST1300. On the ST1100 it had funny effects on the neutral light when the clutch was pulled and the sidestand was down - which sounds similar. But it was wired into the harness electrically. I think the signals are processed by the ECM on the ST1300 electronically so it is likely to have a slightly different behaviour.

I'd need to study the circuit diagram to check if this is possible.

jfheath said:

If the switches are ok, it could be the connectors/wiring. But when I first read your post, I wondered if it could be the clutch diode (3 pin fuse look-alike, at the back, sideways, in one of the fuse boxes). It has the job of preventing signals from one device from interfering with the other. I haven't looked at how it would behave on the ST1300. On the ST1100 it had funny effects on the neutral light when the clutch was pulled and the sidestand was down - which sounds similar. But it was wired into the harness electrically. I think the signals are processed by the ECM on the ST1300 electronically so it is likely to have a slightly different behaviour.

I'd need to study the circuit diagram to check if this is possible.

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Hay, I can check that! I have plenty of extra parts floating around to be able to swap things out!

It'll probably have to wait for the weekend for me to get to it, but I'll see what I can do to figure out which one needs swapping!

Well, nearly 4,000 miles later and parts replaced. Unfortunately, nothing I have done has resolved the problem! After a chat with the technician at my local dealer - used to be Honda but is now Suzuki but the Honda-trained tech is still there - we decided to start by replacing the plug caps. Couldn't see anything wrong with the originals but changing the caps is probably the easiest change to make. Mind you, at £48 EACH it was a bit of a big gulp!
So, plug caps replaced - no difference.
Next step, the HT leads. These were replaced with new - no difference.
Next, and by now the last throw of the dice, the coils. New Honda coils are £300 the pair (!) so I decided to get a pair from a local breaker. Many Hondas use the same coils as the ST and I picked up a pair from a CB1000F for £25. These were fitted and, guess what, no difference.
I don't have the luxury of being able to pull the bike to bits and try one thing after another in the hope I'll strike lucky. It's a working bike and I need to be on the road. So, my dealer is going to use his Trade contacts to find a new or nearly-new ST for me and my old faithful 2009 177,000 miler will, somehow, be disposed of.
A great pity but there it is. The ST is dead, long live the ST!

J.Murphy said:

... The ST is dead, long live the ST!

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Bummer, sorry! 4:

Know anyone with a digital oscilloscope ? I would put an oscilloscope on the crank & camshaft sensors to see if those signals are good. Then look at the two primary coil signals along with the +12 volts on the other side of the coil primary. Gotta do some logical troubleshooting.

You may want to first check the ground at the coils mounts.

What about fuel pump acting up when it gets hot? It's getting up there in miles. A mechanic with a scope and low-amp current probe can do a current signature waveform of the pump, and from there can determine its operational rpm and possible failing commutator bars. Do the test after the pump is good and warm and the engine is acting up.

Jim Van said:

Know anyone with a digital oscilloscope ? I would put an oscilloscope on the crank & camshaft sensors to see if those signals are good. Then look at the two primary coil signals along with the +12 volts on the other side of the coil primary. Gotta do some logical troubleshooting.

You may want to first check the ground at the coils mounts.

Click to expand...

No, I don't know anyone with a digital oscilloscope. In fact, until today, I'd never heard of one! My problem with "logical troubleshooting" is that the fault only manifests itself occasionally and for a relatively short time. By the time I get home the bike is running sweetly so I guess all the readings, etc will show normal. Re the coil grounds: when the coils were changed all the connections and the grounds were as clean and bright as could be.
Thanks for the input.