Running on one cylinder. Help!

[elanski]

Tried starting the plus 2 this morning and it took about 7 attempts and when it did fire it sounded more like Stevenson's rocket than a twin cam. Was shaking all over the place and wouldn't idle at all, sounded really rough and just kept dying on me.

Thinking perhaps I'd lost a cylinder I set the idle a bit faster so it wouldn't stall and proceeded to pull the spark plug leads out one by one to determine if one of them wasn't doing anything. Long story short, there are THREE leads which make no difference to the engine if they are in or out. So clearly only one cylinder is firing anything like it should.

It seems likely to me that the problem lies with the distributor but I am already at the limit of my non existent technical knowledge. Before I start poking about with the disi:

1. Am I likely to be on the right track here?

2. What should I be looking for as a likely fault on the distributor? Everything is plugged into firmly, thats as far as I got.

3. It has electronic ignition btw, could that be the problem rather than the disi?

Weird thing is everything worked fine 3 weeks ago when I last used the car. Seems to have sprung up suddenly.

Any advice very welcome.

Thanks

[types26/36]

Before you get too deeply involved in distributors, compressions and carbs etc. take out the spark plugs and see what they look like, if all black and or oily just fit a new set.
Sometimes after standing for a while and then trying to start the plugs get all fouled up with the use of the choke and pumping away on the accelerator pedal.
It is quite difficult to clean them without the proper equipment....do garages still have plug sandblasters? .....I doubt it these days! another little trick that sometimes helps is to warm the plugs up either in the oven or with a naked flame.....you then have to be quick to refit before they get cold.

[simonknee]

If you don't have new plugs with you take out the existing and whilst you are giving them a clean with a wire brush all that fuel sloshing around in the cylinders will have evaporated too..

[69S4]

I had that problem a couple of months ago although with another vehicle rather than the Elan. The plugs only had a few miles on them and they'd all spark when checked externally so it couldn't be them, could it. Brian's tip of heating the non firing plugs up was my first port of call - I used a blowlamp and that would get a few more cylinders firing. Other things I tried included closing the plug gaps down to 15 thou and rubbing pencil lead on the tips before putting them back in the engine. All of these helped and eventually I could get three cylinders firing - but not always the same three. Swapping to another set of used plugs gave the same result. Eventually I went back to first principles, checking and changing plug leads, caps, points, condenser, timing etc. When I put a brand new set of plugs in it started instantly and hasn't been a problem since. Moral of the story - try a new set of plugs before tearing the distributor to bits.

[Tonyw]

Back in the days when spark plugs were cleaned as a matter of course (unlike today fit and throw away) we did use a sand or grit blaster to clean all of the carbon off, we then opened up the gap to get a thin file in to gently file the electrode and earth to provide new metal, thiis usually made it possible to keep plugs going for ages. Filing seemed to make it easier for the spark to jump accross the gap, using a wire brush tended to leave a very slight ampount of metal on the insulator causing the spark to track down the insulator instead of jumping accross th gap. Many plug cleaners back in those days also had a plug tester so after cleaning you could test the plug for efficiency.

A new set of spark plugs will at least make sure you can cross that off as a fault and these days tey are not very expensive.

Tonyw

[alaric]

Hi. I'd take a look at the centre lead to the distributor, and at the connections to the electronic ignition - especially the earth. With elec ignition I would expect to get a shock from holding onto an ignition lead, so that's possibly a clue that it may have nothing to do with the spark plugs themselves.

Sean.

[Orsom Weels]

Another thing to check if they've been in there for a while is the pointed screws that hold the leads in the distributor cap, I recently had cause to replace a lead & found these screws to be quite rusty when I removed them. It must cause a bit of resistance & I'm sure I have a fatter spark at the plug now I've replaced them with nice new clean ones.
Regards, Tim

[Matt Elan]

Sounds like Spark plugs to me. Also it appears that there have been counterfiet NGK plugs out there which fail quickly.

[twincamman]

clean the plugs with quick start --'start ya bastard --' or any ether based spray can and a rag , no wire brushes or sand blasting the plugs this will ruin the motor --ed

[elanski]

Thanks for the replies. Well there's something I learnt - Never assume anything about twincams. I was so sure that as the spark plugs were only a couple of months old they wouldn't be a problem. It was also odd that this happened suddenly so I thought it must be some sort of electrical connection problem or failure. Needless to say it was indeed the sparkplugs themselves. So thanks to everyone that suggested that. They came out black, sooty and more worryingly, oily. Working fine again now they have been replaced.

So back up and running but the question now is what has caused my spark plugs to foul up in such a short period of time and miles? Engine has an oil leak but has run fine up to this instance.

[Craig Elliott]

One thing you may find is that you need to run a hotter (I think??) plug than recommended in the manual for normal driving - e.g. NGK BP6ES rather than BP7ES. I've had similar problems with sooting up in the past that this has solved. Seems strange though that it's suddenly happened - when you last used the car before it went wrong did you get stuck in traffic or something?

[gav]

Craig
I have been working through an intermittent misfire problem with my twin cam and have decided to change the plugs and leads.
In checking the NGK site, I think the lower numbers are cooler plugs.
Does that mean your engine runs better on cooler plugs?
Thanks
Gavin

[rcraven]

I think the lower numbers are cooler plugs.

No, with NGK the lower numbers are hotter, i.e. the plug gets hotter. That may or may not be a good thing for your engine. There are some reasonable explanations under the General Questions section of this site: http://www.ngk.com/faqmain.asp and here: http://www.ngk.com/charglossary.asp?kw=Heat+range.

[gav]

Thanks Robert
I was looking at the UK Motorsport section which said the higher the number, the hotter the plug.
I might give one of the UK dealers a call to clarify - it is highly likely I have picked it up the wrong way round!
Thanks
Gavin

[alaric]

Glad it was such an easy fix. I'm going to try swapping mine now.

Sean.