Running rough at idle

[Atkins]

I think I'm having a misfire at idle on my 2003 ST1300.

I pulled my spark plugs. Do these look bad?

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[Duporth]

Most idle problems I have read about re the ST1300 seem to be caused by blockage in the 5 Way Tee in the vacuum hoses running between the MAP sensor and the starter valves. At least this is a first point of call. I don't know how many miles your plugs have travelled. If under suspicion and seeing you have them out, I would fit a new set and be done with it. They are low cost. Then try the idle again. If idle is still rough, head for the 5 Way Tee and there is much guidance on this great forum on how to do it. It is pretty straight forward if you read up a bit. It must be, I have done it!
Good Luck , D

 

[Clutch]

I agree. Black sooty plugs equals too much fuel and the Map sensor plugged can cause this over time. I had the same problem but also had an FI code for the Map sensor. Cleaned the plugged 5 way vacuum tee and is right as rain now.

 

[jettawreck]

I think if you had an actual "misfire" you would have a engine code (FI light) for it, but those are pretty black. Dry/sooty or wet??
Oil level correct? Any oil consumption? Air filter clean (unlike this one) and/or airbox inlet unobstructed?

So many possibilities, certainly including a clogged up 5 way.

 

[Atkins]

Previous to checking the plugs, I did clean the 5 way tee, and replaced vacuum lines to it. There is also another tee off the sensor, that I think is for the cruise control. Cleaned it too, but did not replace that vacuum line. Not really sure where that one goes to on the other end. Also the cruise control does not actually work. So maybe that is a factor?

The plugs were not NGK CR7EH-9 as the manual suggests, they are NGK CR9EH-9. So I will probably replace with what the manual says. I have a small commute every day, so maybe they're not getting hot enough for the colder plugs. I'll replace those when I can buy them on Monday.

I also cleaned the air filter, K&N and reoiled it. It wasn't horrible, but was worth cleaning since I had the box open.

Also just changed the oil and filter a few days before. Oil level looks good, maybe a touch high?

Maybe the map sensor itself is bad?

I was only thinking misfire because it does not sound smooth at idle.

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[Atkins]

Forgot to add that I didn't find any obstruction actually in the tee

And the plugs were wet. And the air box inlet was unobstructed.

 

[Redneck]

Mine was hard starting a running a little rough, I put in some fresh non-ethanol premium and 6 oz of Seafoam and it cleared up. Can you clean the map sensor like on a car? With gas prices up they probably aren’t selling enough premium to keep fresh gas in the ground. They just switched to the winter mix so there is probably more than a little “bad gas” out there.

 

[Al Gully]

Mine has started running rough when I get down to 2 bars on the gas gauge, running in city conditions at rush hour both times.
I get a funny stench coming from the exhaust and then it wants to stall, like it's running out of fuel. Filled it up with chevron 92 octane and all is well now. Need to run out the fuel to check the 5 way tee.
Will be watching this post to see if I can pin it down to some of these suggestions.

 

[Redneck]

http://zhome.com/ZCMnL/PICS/winterGas/winterGas.html

Fresh non branded gas is probably better than old “top tier “ gas. Who knows what happens during the transition when they mix the two blends,,,What would summer blend gas do in the winter?

Using summer blend gas in winter will make your vehicle much more difficult to start, especially when the engine is still cold. It may also make your vehicle run rough even when started.

 

[cdnemsguy]

ABsolutley new plugs are inorder, and a starter valve sync would help the rough idle. Those plugs are bad an fouled for some reason, although if it was a MAP sensor, or sensor of any kind a code would be thrown. As long as the 5 way t is clean, I would try new plugs and a sync. Fuel could be an issue but unless you got a bad batch or it is old, I doubt that. Smell the fuel and you can tell.

 

[SupraSabre]

I would replace the spark plugs with Iridium plugs:

NGK Iridium IX Spark Plugs

 

[Atkins]

I forgot the dealer is closed today, so I'll have to get plugs tomorrow. I went ahead and ordered the carbtune tonight. So I am hopeful doing a sync will resolve the issue, as well as the recent air filter cleaning and changing plugs. Just kind of bummed I'll have to wait to get it resolved. It really doesn't run well right now at idle. I had just been keeping the revs up for a while manually with the throttle.

Thanks everyone for the helpful suggestions. I'll report back on it later.

 

[cdnemsguy]

I went ahead and ordered the carbtune tonight.

Perhaps a member in your area if any might have a carbtune or similar to help out? Anyone? Well once you get it there are some good articles or just ask if you need a hand to sync. On top of the sync, I am still suspect that you have a vacuum leak on some hose, as you have to manually keep the revs up. That to me smells of a vacuum leak.

 

[Atkins]

See how the boot on the plug wire is partly cut off. Does that have to be replaced?

I'm guessing the grommet on the plastic cover but down on it at some point.

Not sure if I did that or if it was like that already.

 

[cdnemsguy]

The boot goes in quite a ways, and from the photo it doesnt look like it has been arcing. I wouldn't think to replace it unless I saw any signs that it could arc.

 

[gsforster]

Mine has started running rough when I get down to 2 bars on the gas gauge, running in city conditions at rush hour both times.
I get a funny stench coming from the exhaust and then it wants to stall, like it's running out of fuel. Filled it up with chevron 92 octane and all is well now. Need to run out the fuel to check the 5 way tee.
Will be watching this post to see if I can pin it down to some of these suggestions.

I think your fuel pump may be on its way out. Pump runs hotter at low fuel levels and loses rpm and pressure/flow. Filling tank cools the pump and it picks up rpm. A good tech with a labscope and low current clamp can graph the pump's current draw waveform and calculate the pump motor rpm. If this is done when the bike is acting up it would confirm bad pump. Non intrusive test and only requires seat removal to access pump wires for the current clamp. A good pump will spin 5-6k rpm or more; a bad one wil be obvious and a lot less rpm. I do this regularly on cars where the fuel pump has not quit altogether but is failing and causing these intermittent problems.

 

[Al Gully]

I think your fuel pump may be on its way out. Pump runs hotter at low fuel levels and loses rpm and pressure/flow. Filling tank cools the pump and it picks up rpm. A good tech with a labscope and low current clamp can graph the pump's current draw waveform and calculate the pump motor rpm. If this is done when the bike is acting up it would confirm bad pump. Non intrusive test and only requires seat removal to access pump wires for the current clamp. A good pump will spin 5-6k rpm or more; a bad one wil be obvious and a lot less rpm. I do this regularly on cars where the fuel pump has not quit altogether but is failing and causing these intermittent problems.

I was thinking the same thing, fuel low and the pump gets hot. But I had fuel in the lower tank.
When I filled up right away and it only took 20 litres, so it still had 7 litres in the tank.
Not letting it drop to 2 bars as that's when it starts acting up.
Now have to look for a pump, any suggestions as I've heard we can use Honda car fuel pumps.

 

[gsforster]

I was thinking the same thing, fuel low and the pump gets hot. But I had fuel in the lower tank.
When I filled up right away and it only took 20 litres, so it still had 7 litres in the tank.
Not letting it drop to 2 bars as that's when it starts acting up.
Now have to look for a pump, any suggestions as I've heard we can use Honda car fuel pumps.

You are probably not going to like my opinion but I would strongly recommend the hugely expensive oem assembly. To me they just seem to last the longest, and also
everything else in there (filter, strainer sock and fuel level thermistor) gets renewed at the same time. The huge expense is what justifies testing before replacing. Suspicions need to be confirmed by testing and diagnosis before just throwing one in I can't stress that enough To me, if I had a break down far from home due to a cheap part that failed, the resulting expense and hassle would far outweigh the few hundred bucks I saved IMHO. Yes I have seen on here where some have confirmed that Honda car pumps fit and work. That being said I suppose it's an easy enough repair and one could likely fit an aftermarket pump from autoparts store in a parking lot far from home in a pinch...
Test first, and if it turns out you do need a pump, then if you can fit the part yourself you are already way ahead of the game in labour savings helping offset the parts cost....

 

[Al Gully]

You are probably not going to like my opinion but I would strongly recommend the hugely expensive oem assembly. To me they just seem to last the longest, and also
everything else in there (filter, strainer sock and fuel level thermistor) gets renewed at the same time. The huge expense is what justifies testing before replacing. Suspicions need to be confirmed by testing and diagnosis before just throwing one in I can't stress that enough To me, if I had a break down far from home due to a cheap part that failed, the resulting expense and hassle would far outweigh the few hundred bucks I saved IMHO. Yes I have seen on here where some have confirmed that Honda car pumps fit and work. That being said I suppose it's an easy enough repair and one could likely fit an aftermarket pump from autoparts store in a parking lot far from home in a pinch...
Test first, and if it turns out you do need a pump, then if you can fit the part yourself you are already way ahead of the game in labour savings helping offset the parts cost....

Before reading your reply, I just pulled the trigger and bought a HFP-382H-S15 from:
www.highflowfuel.com for $69.
Also getting:
Fuel Filter (16900-MBG-013)
Filter, Fuel Return (16714-MBG-000)
Gasket (17574-MN5-000)
Thanks for helping me troubleshoot this, I'll pack a Gerry can and let the fuel run down one last time while I have the new pump/gaskets/filters in hand. Just want to confirm it wasn't bad fuel or water in the fuel. I know they just switched over to the winter fuel grade and was wondering if that was causing the problem also.

 

[gsforster]

Keep us posted