S4 misfire

[carr01]

Recently had a very wet journey back from blackpool to manchester, all went well, since then the bike's began to misfire usually when hot.
I rang up Manchester Ducati to chat/ book in, in conversation with them it it seemed this is a common problem with the ingress of water into the spark plug caps, particulary the front one. Once water gets in it can't get out and turns to steam when hot causing the engine to misfire. Sure enough the front plug cap was wet! now all dried off and sprayed with water displacement fluid.
Haven't had chance to try yet. Anyone had similar?

[Scotty]

yup

odd how such a slight amount of dampness can be such a git

[Runningman]

I recently had the plugs changed on my s4 as part of a routine service, and as you say, the front one was rotten with rust from water ingress, however it was not causing any firing problems..

During the winter months I use a silicon based water repellant which I spray around the undercarrige after washing of the salt. When I start the bike in the morning it looks as if I'm on fire as the excess burns off, but it seems to do the trick.
R

[jamie]

exact same problem on my S4. Posted it a little while back but no help. Have cunningly fashioned an extension to the lower part of the front mudguard from an old carbon mudguard (knew it would come in handy) to create a 'mud flap'. It improved the problem as now the water does not jet directly from front tyre to plug. An absolutly ridiculous thing to have to do though, it doesn't look tooooo bad. But heh, mines also got a rack so thats me off the artistic roll call. This lash up, however, failed to cure it completely, so have now run a bead of silicone around the rubber flange (mm rubber flange) and the coil. But interestingly enough, yesterday after misfiring i found the coil almost out. I dunno.....

[carr01]

Thanks for info on customised mud guard,it hasn't rained for a while since I dried the caps off and sprayed with silicon, it hasn't helped any if anything it's getting worse. don't know if its related but when throttling of at high revs it sound as if the rear or the bike is exploding, as it pops and farts down through the rev range. in the mean time I've have booked in at manchester ducati for investigation in August, will post the outcome.

[Scotty]

ummm i found if you run the bike a bit till its warm then remove front coil and wipe any moisture off and repace , repeate a few times untill all moisture is gone

humm i once had a missfire that was eventually traced to some crud in the fuel line somewhere some strange plastic disc thing

[Didge]

Check that the exhaust bolts are not loose in the heads. Mine was misfiring on the over-run for this very reason, as cold air was being sucked into the hot gases.
Nipped them up, job done.