Missfiring

Engine Oily Bits, Ignition, Fuelling, Cooling, Exhaust, etc.
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tomd
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Missfiring

#1 Post by tomd » Sat Jan 28, 2012 3:39 pm

Hi, I am running a 2500S in Berlin. It has been suffering from an intermittant missfire which is becoming worse. It was a short dropping out of one cylinder and now it has become more of a splutter. It stalls and starts badly.
Leads, Coil, Resistor, Distributer cap and plugs have been replaced.
Do you have any suggestions. The car is from 77 and has covered about 94 thousand miles.
best regards
tom
Mk1 2000 Automatic LHD (1966)
2500S (1977)
Herald 1200 (1969)

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valencia
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Re: Missfiring

#2 Post by valencia » Sat Jan 28, 2012 5:33 pm

Hi Tom,
You seem to have changed most of the bits but many of us have had problems with the rotor arm. You should change it for the better quality type from Chris Witor or distributor doctor, (red in colour). Some of the other aftermarket types have a poor design and tend to short out. You don't say if you are still on points or not but if you are I would change the condenser as well. Let us know how you get on.
Regards,
Mike
Lancashire

Clifford Pope
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Re: Missfiring

#3 Post by Clifford Pope » Sat Jan 28, 2012 6:10 pm

I can't remember whether this distributor has a little bit of braided wire inside to connect the sliding plate to the base plate?

Ignition switch worn contacts? Try running a wire direct from live to the coil.

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Re: Missfiring

#4 Post by Mike Stevens » Mon Jan 30, 2012 12:28 pm

Hi Tom,

You said you have replaced the 'Resistor', but a '77 car would have the ballast resistance in the wiring loom, not a separate resistor.

Does the miss seem to come from just one cylinder or at random? If just one, I'd check the compression pressures to make sure they're OK.

I've had an intermittant miss before due to a band connection onto the coil - the wire had parted from the crimped connector and going round left hand bends made the engine lean over and pull on the wire!

Although more likely to be ignition-caused, I wouldn't write-off carburation issues completely, especially if you've tried most things ignition-wise.

Cheers,
Mike.
(South Oxfordshire)
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Re: Missfiring

#5 Post by tomd » Mon Jan 30, 2012 10:30 pm

Thanks for your comments. Mike I meant condenser. It started off as a missfote on a single cylinder but now seems to be less isolated. I'll start with rotor arm and wire.

Tom
Mk1 2000 Automatic LHD (1966)
2500S (1977)
Herald 1200 (1969)

Mike Stevens
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Re: Missfiring

#6 Post by Mike Stevens » Tue Jan 31, 2012 12:40 pm

Hi Tom,

Ah, right, I now understand!

Good luck with the fault finding.

Cheers,
Mike.
(South Oxfordshire)
Register Member No 0355
1971 2.5PI Saloon Sapphire blue
1973 2.5PI Saloon rust some Honeysuckle
1973 Stag French blue
(1949 LandRover was blue should be light green!)

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Re: Missfiring

#7 Post by tomd » Sat Feb 04, 2012 11:40 am

I tried the red rotor arm but unfortunately it didnt improve the situation. The distributor does have a bit of braded wire so I will try this. (still on points) Is there not a potential problem of damaging the coil by bypassing the ballast resistor? Compression still to be tested.
regards
tom
Mk1 2000 Automatic LHD (1966)
2500S (1977)
Herald 1200 (1969)

Mike Stevens
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Re: Missfiring

#8 Post by Mike Stevens » Tue Feb 07, 2012 12:51 pm

Hi Tom,

A '77 car should have the ballast resistor in the loom, not fixed next to the coil, but you could bypass it with a wire direct from the battery to the coil '+'. For a short period of time, this would be OK, but the coil will be over-rated and will get hot, eventually (probably) leading to failure.

You could try putting a bulb on the points side of the coil to battery positive, (or ignition switched positive). This should come on as the points close and and off when they open. If the flashing is erractic at the same time as the engine missing, it would indicate that it is an ignition fault. A bulb may not show the flashes (as the filament has to heat up and cool down!) but an LED would, if you can source something suitable. Dunno, just a thought.

Cheers,
Mike.
(South Oxfordshire)
Register Member No 0355
1971 2.5PI Saloon Sapphire blue
1973 2.5PI Saloon rust some Honeysuckle
1973 Stag French blue
(1949 LandRover was blue should be light green!)

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Re: Missfiring

#9 Post by Charles H » Tue Feb 07, 2012 3:25 pm

I would go for an Aldon ignition system that fits straight inside the distributor. Eliminates all the points and condensor problems for ever! :wink:
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Re: Missfiring

#10 Post by tomd » Sun Mar 18, 2012 10:29 am

thanks for your comments.
It was the points. I checked and adjusted them at the start of the problem, but should have just replaced them.
I put new ones in and the problem went. There was quite a lot of oil inside the distributor I don t know if this was also a problem?
Now it runs great again. Electronic ignition will be fitted soon.
regards
tom
Mk1 2000 Automatic LHD (1966)
2500S (1977)
Herald 1200 (1969)

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