Xantia misfire problem.

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AndyP
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Xantia misfire problem.

Post by AndyP »

1.8i, 8 valve, 130,000 miles
I have a bad misfire between about 1000-2000rpm. Worse when cold than hot. Sometimes it's almost a complete cut-out and sometimes it's clearly chugging along on a couple of cylinders. I have changed the plugs and the ignition leads but it hasn't really made any significant difference. Hotter plugs seem slightly better, but it's far from perfect and it's definitely getting worse.
I read the Haynes manual and it helpfully informed me that the 8v has dual ignition coils/circuits (which may explain part of the problem) and that a Citroen is far too complicated for any normal person to understand, so I should take it to a specialist - sometimes I wonder why we buy these things !
Has anyone experienced (and fixed) a similar problem before ? Any clues to look for, like poor connections in a particular area, or is it likely that one of the coils is preparing to shuffle of this mortal coil (ahem!). In my experience failing coils usually do so when hot, not cold, which seems to the the opposite of my problem. Is it possible to read the fault codes with any normal tools such as computer, multimeter, oscilloscope etc ?
So any thoughts or hints gratefully received. Thanks.
xantiav6
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Post by xantiav6 »

It could be a failing coil.
You could try closing up the spark plug gaps to about half the normal gap which needs less voltage to spark, and if it runs better, then it is almost certainly a coil problem.
If you have a timing light, you could connect it to each plug lead in turn (I am assuming that you can get to them on your engine) and see if the timing light flashes become irregular when the misfire occurs. This will confirm that you have and ignition problem, and which cylinders are affected.
regards,
mike
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Post by Mosser »

If the coil is failing and closing the plug gap to half the specified clearance fixes it, would leaving it that way have any implications?,
I'm just curious as to what reducing the plug gap does to the running or plug life??
AndyP
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Post by AndyP »

I like the idea of using the timing light to verify which plugs are missing but as this only seems to happen under load then even my Heath Robinson type plans may find that difficult to implement. So I will give the plug gap theory a go.
In answer to the plug gap question I would expect fuel economy to drop a little due to the less efficient combustion, doubt whether it would harm the plug much though.
I'm kind of expecting that one of the coils is breaking down, so as a new one appears to be about £39+VAT then this could be the favourite option - unless someone has a spare 2nd hand one they would be prepared to sell ?
Thanks again
AndyP
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Joined: 26 May 2004, 04:59
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Post by AndyP »

Well the situation was getting worse fast, it was misfiring up to 3000rpm and being a right pain in the backside, so I ordered a new coilpack from GSF (£38.50 +vat)and fitted it this evening. Sorted, starts easily, runs smoothly and I'm a happy old Hector. I also fixed (yet) another water leak from around the thermostat/coil mount housing, so I'm another step closer to being water tight. Really need to get that sorted before the winter because I'm dammed if I'm gonna be putting in a litre of anti-freeze every week ! Course once it started warming up I spotted another tiny leak from the little brass pipe that comes off that self same housing - that'll be a job for tomorrow morning then ....
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