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Discussion Starter · #1 ·
Another day, another attempt at the same post. If this works, could someone remove the dodgy ones below?

Please help:

My S4 seems to be developing a problem at low revs when it gets up to operating temperature. It appears to misfire (it almost sounds like it's trying to be a twin) when I pull off gently, typically in first gear at a junction.

It only seems to happen below 4,000 revs and only when it's warm, and it's only really done it in the last month or so. I was riding around it, but it appears to be getting worse. I think it's different to the "fuelling issue", since I didn't notice it for the first 5 months I had the bike.

Nothing's been changed since I've owned it.

Any ideas before I take it in to be looked at?
 

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Not sure what it is but I think my S4 does the same thing now and again. Generally if I start it up again when it's still warm ( Roughly 50-60c water temp ) It will pop alot and like you say is different to the usual dead spot below 5k RPM that I'm used to.

When it does it I just keep it above 5-6k RPM and it normally goes away once it's back up to proper temprature.

I put it down to the ECU getting a bit messed up with the cold weather and semi-warm engine, but since it doesn't stay like it for long on my bike I'm going to hang on until it's 6000 mile service before I get it checked. Would be interested if you find any more info on why it happens though? :???:
 

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Not sure if this is what you guys are talking about but this is off of speedfour.org:

Low Speed Surging

Some Triumph Speed Four owners have reported low speed surging or a jumpy throttle, at around 3,000 rpms. The typical work-around is to avoid that range in the throttle by changing gears. Some have reported success with a retuned engine map. I consider it a minor problem, as it only affects smoothness at low speeds, but it is something to be aware of.
 

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Misfire?
or
Hesitating when you roll the throttle and then coming on song with a big kick?

Standard can on the bike?
 

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Discussion Starter · #5 ·
Misfire. It sounds sick, like it's missing a cylinder or two, then fires off.

Bike is standard, including a standard can.
 

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How many miles and under what conditions? If you have been running a bit rich and have done a lot of low rpm riding, you could be fouling a plug. My TT600s would carbon up a bit if they weren't aired out occasionally. Sorry officer, I was just clearing the plugs.... :razz:
 

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Different bike, but I had the same problem with a Daytona 1200. Only occured when hot, when left to cool would sort itself, until up to operating temp again, then problem would start again. Local bike shop suggested the pick up coil, on the end of the crank. Changed that, problem never came back. I am not a mechanic, did not even know what the pick up coil did, but I can un bolt things and put another one back! Daytona 1200 was a carb'd bike so maybe the equivalent is the crankshaft position sensor? No idea if this might be the problem or even the solution, but I know what it is like having a persistant fault, that you can never get to the bottom of,you will try anything!
Good luck
 

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Cant be sure if its the same problem, but my TT would have very similar symptoms, but it reacted when it was at a slightly elevated temperature, about 120-126C. around here the darn thing would hate the revs lower than 5k. i just chalked it up to being a ECU problem. I dont think it was the fuel plugs, cuz i deffinently cleared those up about once a week :razz: . But right before i was about to take it in to get the bike and cooling system checked, exhaust valves went bad :( . i doubt that the two problems are related, but be cautious. i just about have a new engine in the bike, so as soon as i take her for a hard ride, ill let ya know if the same problems present themselves.
 

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Discussion Starter · #9 ·
Hmm, I was wondering about valves and I'm now a bit more worried about that.

In answer to Will's question, I ride to and from work (20 miles round trip) every day. The trip is a mixture of dual carriageway and traffic, but recently given the cold weather I've not caned it. I did cane it a bit this morning and it seemed a little better, so I'm hoping it's the plugs.

Bike has 8,500 miles, last serviced in August when I had it at around 4,500 miles. At least, there's a stamp in the book, but they probably only changed the oil.

Think I'll change the plugs to see if that makes any difference. If not, I'll get the valve clearances checked (because I'm paranoid).

Thanks for all your replies. Grateful as ever.
 
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I had an S4 till Aug all standard got up to nearly 10k low mid range was a bit on/off but good. As I live in Bristol I am happy to chew it over with you if that helps before spending money at the dealers??

PM me

Jon G
 

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So it's a misfire, at low revs, when the engine is under load, bike is standard?

and

No-one has worked on your bike recently so nothing is messed with the air intake etc.,

Best guess, although unlikely for the low miles, would be blocked fuel line/filter or broken down plug/coil. Really need to hook up diagnostics to start eliminating things though :???:

PS Hello Jon!
 

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Mine's been getting worse over the past week or so (Misfiring pretty much every day now). I mentioned about it to my old man who's a mechanic, his first guess was it's likely to be carbon deposits on the injectors/plugs. Probably due to the short distance to work everyday and the slow speed/low engine revs I have to do in the traffic.

He's suggested trying a fuel additive designed for injected engines as these should have something to help keep them clean & working well. I'll give it a try and see if it makes any difference when I next fill up and let you know.

[ This message was edited by: big_chris on 2007-02-20 09:33 ]
 

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Discussion Starter · #13 ·
All very curious. I've uploaded a vid (it was going to be audio only, but it wouldn't have it) of it in the dark. You can clearly hear the misfire - the engine's at 82C. It was a real pain today, as I had to drive through and around town and slow hill starts were, well, interesting. I suspect the car drivers thought I was being impatient.

Video is here - we'll see if it's the same thing: s4_misfire.asx (5.43MB). I hope the vid will work - my 'net connection is corrupting things randomly at the moment.

Will try the fuel additive, I was debating it today. NOTE - they say to add the whole lot to a tank, but they mean a car tank, not a bike tank, so be careful!.

[ This message was edited by: themaster on 2007-02-20 13:11 ]
 

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On 2007-02-20 13:08, themaster wrote:
Will try the fuel additive, I was debating it today. NOTE - they say to add the whole lot to a tank, but they mean a car tank, not a bike tank, so be careful!.
Glad you reminded me of that! I've stuck half of the small (50ml) pots of REDEX in it today so we'll see how that does.

Going by that video I think I must have the same problem. Well it sounds similar anyway! :-D
 

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Discussion Starter · #15 ·
I added Redex too this morning. 30 miles since and practically no difference. It might be a bit less bad, but we'll see.
 

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On 2007-02-21 12:19, themaster wrote:
I added Redex too this morning. 30 miles since and practically no difference. It might be a bit less bad, but we'll see.
It will take some time to clear out. Don't forget to get the engine good and warm, then flog it hard every so often. They really need a good whuppin' every now and then to stay healthy. My 2000 TT600 got silted up so bad that it was hard to start if I didn't air it out periodically. It had a power optimized map in it, and that compounded the problem, but it was fine as long as I could open it up on a regular basis.

[ This message was edited by: Will on 2007-02-21 12:35 ]
 

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On 2007-02-20 13:08, themaster wrote:
All very curious. I've uploaded a vid (it was going to be audio only, but it wouldn't have it) of it in the dark. You can clearly hear the misfire - the engine's at 82C. It was a real pain today, as I had to drive through and around town and slow hill starts were, well, interesting. I suspect the car drivers thought I was being impatient.

Video is here - we'll see if it's the same thing: s4_misfire.asx (5.43MB). I hope the vid will work - my 'net connection is corrupting things randomly at the moment.

Will try the fuel additive, I was debating it today. NOTE - they say to add the whole lot to a tank, but they mean a car tank, not a bike tank, so be careful!.
Just heard the clip - Jeez that sounds proper shagged :eek: and it's running rough even when the engine isn't under load.

You could check the plugs & air filter but to be honest I really am guessing.
If I understand things right, you said that when the engine is cold (and therefore the fuel mix and ignition are altered) you don't have the problem at all?
If you can find someone local with a Tuneboy they can also check things like dwell time for each cylinder which would help identify whether there might be an ignition problem.
 

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Discussion Starter · #18 ·
Would a fouled oxygen/lambda sensor cause this kind of problem? The reason I ask is there's currently a furore erupting in the UK about contaminated petrol (see http://news.bbc.co.uk/1/hi/uk/6405051.stm). I haven't bought petrol from the stores mentioned, but regularly use Asda/Walmart fuel.

The Redex seems to have improved things a little, but I'm now about half way through the second tank and no real difference.

One weekend I'll get round to checking the sparkies.
 

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Sagem injection like on a Speed 4 doesn't use an O2 sensor in the exhaust.
 

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Yeah, heard about the dodgy fuel but I've always used Esso so shouldn't be that.

I think I'll book it in with the dealer today and get them to check it out. Redex made a slight difference but it's still misfiring loads below 5k rpm once upto temprature. Doesn't have the problem when cold but I guess thats because the ECU runs it a bit rich initially.
 
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