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Anon
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Missfire - rather persistant

Hi experts.

I have an occasional missfire on my 2.3 CF. It usually will occur, for instance, when putting my foot down at low revs, if I allow the revs to build then it will dissapear.

So far I have fitted a new set of spark plugs from the club), these are S U Butec ones, not a maker I have come across before. I have changed the plug leads for copper cored, together with caps and fittings (new) changed the condenser (new old stock) the rotor arm (new old stock) and the coil, a sports item from a mini specialist but a Lucas unit.

When I had the distributor cap off I noticed the carbon contact in the centre was broken so I have ordered another new old stock cap from Ebay.

My question really is, has anyone had any problems with the SU Butec plugs? it sounds and feels like one cylinder missing occasionally and the rest of the ignition system is almost all new now.

Cheers for any help on this, love the van and its going so much better these days than it was so would love to get these last few issues nailed.

Mike
Tue 26 Jan 2016 @ 10:33 Edit this messageQuote this messagePMQuote this message
Anon
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Misfire.

Hi Mike,

First I would check the plug gaps mine are set at 28thou and the plugs are A/C the type that the engine was designed to run on, make sure the plugs have a tapered seat and that they are tight and not shorting against the exhaust alloy
heat shield.

doujoy

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Tue 26 Jan 2016 @ 13:45 Edit this messageQuote this messagePMQuote this message
Anon
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Thought.

Hi Mike,

Did you notice the misfire before you changed the plugs or has it just started since fitting the new plugs?
Old workshop training, always go back to the last thing you have changed or reset.

doujoy

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Tue 26 Jan 2016 @ 19:40 Edit this messageQuote this messagePMQuote this message
Anon
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Hi Doug

I am pretty sure its since the SU Butec plugs were fitted so I am with you on the plugs as the likeliest source of trouble.

I wonder if you could remind me of the number of the correct AC Delco plug for the engine please?

Mike
Wed 27 Jan 2016 @ 13:42 Edit this messageQuote this messagePMQuote this message
bluebedouin
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Mikecsailing wrote:
....

I wonder if you could remind me of the number of the correct AC Delco plug for the engine please?

Mike

There are some CR42CTS plugs on the club auction site

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Wed 27 Jan 2016 @ 14:14 View bluebedouin   Email bluebedouin   Edit this messageQuote this messagePMQuote this message
Anon
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Spark plugs.

Hi Mike,

The spark plug I am running on and have been for over six years are AC 41 5TS, short reach of course set at 28 thou.

doujoy

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Wed 27 Jan 2016 @ 16:12 Edit this messageQuote this messagePMQuote this message
Anon
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Thanks Doug :)
Thu 28 Jan 2016 @ 13:06 Edit this messageQuote this messagePMQuote this message
Anon
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missfire

Hi Mike,you said that you have orderd a new dizzy cap have you fitterd it yet?Cheers Jim.

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Thu 28 Jan 2016 @ 19:47 Edit this messageQuote this messagePMQuote this message
Anon
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hi Jim

It arrived in yesterdays post so I will try to get it fitted this weekend but although the centre carbon contact is knackered I suspect it will end up being the plugs, time will tell :)

Mike
Fri 29 Jan 2016 @ 09:51 Edit this messageQuote this messagePMQuote this message
Anon
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Misfire.

Hi Mike,

Do you know which cylinder and plug is misfiring, does it misfire when hot or cold or just under load?

doujoy

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Fri 29 Jan 2016 @ 10:44 Edit this messageQuote this messagePMQuote this message
Anon
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Hi Doug

I can't determine whuich cylinder it is as it only does it occasionally at low revs under load, ie when you put your foot down to go up a hill in a high gear.

Mike
Fri 29 Jan 2016 @ 15:44 Edit this messageQuote this messagePMQuote this message
Anon
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Hello MC
If you still have the old set of plugs clean them up and stick them in to see if that stops the misfire.

Regards Andy

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Fri 29 Jan 2016 @ 19:28 Edit this messageQuote this messagePMQuote this message
Anon
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AC spark plugs.

Hi Mike,

If you type in (the green spark plug company) you will find they can supply the spark plugs you need.

doujoy

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Fri 29 Jan 2016 @ 20:27 Edit this messageQuote this messagePMQuote this message
Gethin
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I have a few sets of AC delco plugs available
Wed 03 Feb 2016 @ 21:37 View Gethin   Email Gethin   Edit this messageQuote this messagePMQuote this message
Anon
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Hi Gethin

Thanks for the offer, I would take a set or two depending on the price you are looking for.

Mike
Thu 04 Feb 2016 @ 11:25 Edit this messageQuote this messagePMQuote this message
Anon
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Misfire.

Hi Mike,

Since this engine of yours has been rebuilt we should be able to rule out any lack of compression from bad valve seats or burnt valves, broken piston rings
losing you power.
If a new set of sparks does not cure the misfire it could be a manifold problem
which is what I found on my own Bedford, which I cured by removing the manifold and replacing the gaskets and having the alloy faces of the manifold resurfaced
number four cylinder being the where the leak was, plug colour was the indicator that led me to doing that work.
The other likely area effects number two cylinder and that is a water leak into
the cylinder through a badly sealed manifold stud at the bottom of the thermostat housing, again changing the colour of the spark plug when compared with the others.
If you have not yet cured the misfire this might be of some help!

doujoy

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Fri 05 Feb 2016 @ 10:11 Edit this messageQuote this messagePMQuote this message
Anon
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Great information Doug, thank you.

Its hopefully on the agenda for this weekend.

Mike
Fri 05 Feb 2016 @ 10:33 Edit this messageQuote this messagePMQuote this message
Anon
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Well, after renewing much of the ignition (something I wanted to do anyway so I could be sure of it) the missfire finally got diagnosed at the weekend.

In a conversation with Doujoy I remembered him mentioning that his rubber fuel feed line had collapsed internally so I thought I would replace it as a precautionary measure. While trying to get the rubber pipe off the tank spiggot it immediatly became obvious that it was rotten. covered it with podge to move the van and it ran perfectly so I will remove the tank shortly and replace the metal part. I assume it had been sucking air instead of fuel.

Cheers

Mike
Mon 15 Feb 2016 @ 12:10 Edit this messageQuote this messagePMQuote this message
Anon
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Fuel lines.

Hi Mike,

Sounds like it was able to starve the engine when you demanded power just as mine did on its journey home when I bought it, the guy I bought it from told me it had a limiter, and in a way it did!
Very glad to hear you have finally found the cause of your power loss and misfire.

doujoy

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Mon 15 Feb 2016 @ 14:27 Edit this messageQuote this messagePMQuote this message
Anon
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Updating the missfire saga.

I was a bit premature thinking that the corroded fuel feed pipe was the cause of the problem, the tank was removed and a new section of pipe installed and the van taken on a test drive. Sadly it was no better.

At this point I had run completely out of ideas having replaced almost all of the ignition system - plugs, plug leads, distributor cap, rotor arm, condenser and coil. This is why I was beginning to think it was fuel even though it sounded like an ignition fault.

In desperation I handed it over to my pal who rebuilt the engine, it took him a long time to discover it but he finally traced it down to the new plug caps, part of the plug lead kit I fitted to her. The internal resistance of the suppressors in these caps was far higher than it should have been, in the Meg ohm region, I will measure and report for everyone's information.

I have only done 5 miles since this was done but no missfiring at all in that distance and the engine is lovely and responsive.
Thu 10 Mar 2016 @ 12:16 Edit this messageQuote this messagePMQuote this message
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