Got slight mis fire
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Discussion

wetny

Original Poster:

486 posts

242 months

Sunday 14th September 2008
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Have noticed slight misfire above 4,000 rpm with full throttle. I suppose that I will start replacing rotor arm, dis cap, plugs and leads in that order. The only other thing is I filled it up with Morrison's petrol and washed it so could be a bit of water in some where or it has got a dis like of the petrol. Everything else is normal. Could do without anymore car trouble this week, Shogun gearbox failed on Monday.

NWTony

3,006 posts

258 months

Monday 15th September 2008
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Water in the plugs maybe? Gets in under the rocker cover and takes an age to clear on it's own. If it is that you need to seal the screw holes with sealant to stop it repeating.

R.P.M

1,980 posts

251 months

Monday 15th September 2008
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first stop- plugs.

Gad-Westy

16,624 posts

243 months

Monday 15th September 2008
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Before buying any new parts go through the ignition system checking for moisture. 9 times out of 10, this is what causes a misfire, and seeing as you've just washed it....

As mentioned, the plug wells are the most likely candidates. Take the plug cover off, and pull out the ignition leads. Curl up some kitchen roll and push it down each plug well and leave it for a little while to soak up any water. If any bits are particularly wet, stick another down until its dry. Spray some contact cleaner (or WD40) into the ends of the plug leads and reattach them.

Next, pull the dizzy cap off and dry any moisture out from there. A hair drier or heat gun would do the trick. Some contact cleaner in there wouldn't do any harm either. Reattach. I'd pull the plug ends off at the dizzy as well and spray the ends of them. Look for any other connectors that could have got wet and clean them.

Hopefully that'll cure it. But to stop this happening again, I'd seal up the dizzy with some silicon or some tape. Also run a bead of sealant along the uphill edge of the spark plug cover to stop water getting in there again. I tend to waft some wet start/sealent around as well to protect electrical connections. Good luck with it.

wetny

Original Poster:

486 posts

242 months

Tuesday 16th September 2008
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Been having a right nightmare. There was a bit of water down the one plug, but there was also some bits of plastic. I only found this out when the plug spanner would not fit on. Been fiddling about with thin bits of wire and a little torch for ages. I think it must be the remains of an old plug cap. Could get them to move but not get them out. Had visions of taking the head off to give it a good shake. In the end I cut a small piece of hose pipe, taped it on to the vac and sucked it out. Was a little bit of moisture in the dis cap, will leave it of tonight and put it back together tomorrow night. Hope this sorts it out. Plugs look like new, I think Paul Matty must have changed them when I bought it. Only done about 2k since.

insy09

13 posts

233 months

Tuesday 16th September 2008
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i had a mis-fire which lead to flashing management light. I ended taking it to the garage and had to have a new CAT fitted and o2 sensor (i think).

If it is flashing my advice is dont drive it and take it to the garage.


wetny

Original Poster:

486 posts

242 months

Tuesday 16th September 2008
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No flashing lights, sure it will be ok.

Scuffers

20,887 posts

304 months

Wednesday 17th September 2008
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what car are we talking about?

Gad-Westy

16,624 posts

243 months

Wednesday 17th September 2008
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insy09 said:
i had a mis-fire which lead to flashing management light. I ended taking it to the garage and had to have a new CAT fitted and o2 sensor (i think).

If it is flashing my advice is dont drive it and take it to the garage.
Only S1 111s's have MIL and even that was a retrofit.

Grinnders

1,558 posts

234 months

Saturday 20th September 2008
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I recently had a mis-fire... discovered the oil cap had blown off the head !

The seal had gone... so a difference in metal expansion rates probably meant it worked it's way loose.... took the one off the OEM plastic one and job done redface)

wetny

Original Poster:

486 posts

242 months

Sunday 21st September 2008
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Got it all back together, sweet as a nut. Thought it would be a bit of damp in somewhere