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Mpi Misfire


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#1 orcadian

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Posted 14 September 2019 - 04:15 PM

Had my MPI engined Clubman Estate on the road for over 10 years now and recently it has developed a misfire - not a 1 or 2 cylinder job but a real cough when you put your foot down fairly quickly, almost as if you have turned the ignition off and straight back on again. It will rev freely up to the redline as long as you are gentle, so I kind of ruled out fuel pump issues. I had a brand new coil pack on the shelf, so swapped that and it’s exactly the same. Anyone had these symptoms before and found a cure? I have lots of spares I tested out in the early days to make sure I wasn’t saving dubious parts and these include TPS, injectors and all inlet manifold sensors - the only parts I don’t have are ecu and 5as, but doubt it’s the latter. I’ve never had the need to read codes so far but I think there is a unit here in Orkney if I can’t find a solution myself.

Ian

#2 Alice Dooper

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Posted 14 September 2019 - 04:34 PM

Have a good look at the coil pack. I’ve had similar issues in 2 other injection systems.

#3 orcadian

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Posted 14 September 2019 - 05:42 PM

Are you suggesting that the brand new coil pack just fitted, is exhibiting the same symptoms as the one I have just taken off?

Ian

#4 tmsmini

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Posted 16 September 2019 - 03:06 PM

I am assuming you switched over the fuel filter when you did the swap, when was it last changed?



#5 orcadian

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Posted 16 September 2019 - 04:24 PM

Yes, I swapped over the filter plus all injection parts from the crashed JC LE and changed it a couple of times since, the most recent being last season but a new one won’t hurt. I see where you might be right on that one though as it will climb to high revs when driven gently so pump seems ok but it could be struggling during high demand wide throttle situations. If it had done it from conversion time I might have assumed my ‘in van tank’ fitting was suspect but it’s been great for 10 years!

Thanks for that, I’ll get one and try it - I don’t think I have one on the shelf. I’ll report back with the result,
Ian

#6 tmsmini

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Posted 17 September 2019 - 03:10 PM

I don't remember if you kept the stock pump or not, but maybe the "sock" for the fuel pick up is clogged after ten years. I seem to remember the fuel pump was pretty accessible from the side allowing for a check.



#7 orcadian

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Posted 17 September 2019 - 09:32 PM

Hello again,
Yes I used the stock pump, removed from all the original pipe work and made up a pump plate and the sock is the original and dips into the low bulge on the van tank floor. As you say, I fitted the whole module in the vertical end of the tank, so quite accessible. Unfortunately, when this fault first occurred, I filled the tank and it’s still got about 4 gallons in. I won’t get the filter until I go into Kirkwall on Thursday (assuming they don’t have to order one) and might not get to fit it till next week.
Since you first mentioned the filter, it does seem likely (and the sock too!) as it is exactly the same feel as when I first tested it all with a small amount of fuel in - I could get it to cough like this if I cornered really hard and the fuel moved away from the pump inlet.
Thanks for the heads up!
I will report back but it may be a while!

Ian

#8 orcadian

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Posted 21 September 2019 - 10:51 AM

Well, replaced the fuel filter first and took it for a ride this morning into town - about 20 miles. Same situation, under load it kicks as if you turned the ignition off and on. No problem if driven gently. Collected a few things in town, still starts as it always has but fault gone on way home! Tried many permutations - low revs, high gear foot down, low gear, high revs, floor it further - no problem. Can’t imagine that whatever crap in the fuel lines was still there for 20 miles and then the filter has now grabbed it! Not done the pickup sock as there’s a lot of fuel in the tank but might take a look when it’s lower (mine’s on the side of the van tank)

Thanks again for the suggestions, hopefully it’s gone away for good but it’s a Mini after all!

Ian




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