Lotus Elan

'Laser' Ignition Spark Tester

PostPost by: EPC 394J » Sun Jul 12, 2015 1:31 pm

I'm trying to diagnose rather disappointing engine performance from my Plus 2. Pretty much most things on the engine have been recently refurbed. It has electronic ignition and currently using Accuspark 8mm leads.

Before I go down the rolling road/weber tune expense, I'd like to be sure that everything else is up to scratch first.

I fitted Ignition Spark Testers (bought from Halfords) and it's very noticeable that plugs one and three have bright flashes in the testers. Plugs two and four are far less bright. This always happens even after I've shuffled the testers between plugs. So it's not the testers causing this effect.

My question: Might this be significant, or is the existence of a spark simply binary? (ie, it's either sparking strongly or it isn't sparking at all?) Coincidentally it also seems to be the case that the internal fastening in the lead end caps is less positive a fit on those same cylinders? I suspect the internal clips in the caps may be compromised?

Is it reasonable for me to order the Magnecor leads/cap from Sue Miller etc. or am I simply jumping to conclusions/clutching at straws/wasting my money?
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PostPost by: Grizzly » Sun Jul 12, 2015 2:08 pm

Have you fitted fresh plugs? The plugs fail after a while causing a similar result as you describe above, only difference is when my plugs go south i get a splutter when accelerating (almost like a blocked Pump jet) and its harder to start from cold which over times turns into a full blown miss fire.

I've had experience with Accuspark 8mm leads and there not bad until you split the silicone (very soft) or you don't use the little wire prongs that slide into the cut end of the lead before they go into the cap (if that makes sense). There just cheap leads if you ask me just like there Ignition's (i had three Ignitions fail before i even got my car on the road, they just send you a new one until you start to get annoyed then they refund you straight away so you don't make a fuss (cheap Chinese units))
Chris
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PostPost by: EPC 394J » Sun Jul 12, 2015 4:45 pm

Thanks Chris

Have swapped the leads around, and found that the weak sparks which appear in the spark tester, follows the leads. Have also swapped the plugs, but that doesn't seem to affect the spark testers. Did discover that I had 3x NGK BP7ES, and 1x BP6ES. I guess this is ok?

Still not sure whether I'm onto something, or just barking up completely the wrong tree. I guess I'll just order new plugs, leads and cap, and see what happens?

I guess it's all a learning process, so it's all good.
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PostPost by: richardcox_lotus » Sun Jul 12, 2015 8:04 pm

I can't think of any reason why you'd want a single different Spark Plug heat range to the others, unless you were suffering with a specific fouling issue.

NGK 6's are great for me for everyday use. Use 7's for sustained high speed use.

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Richard
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PostPost by: EPC 394J » Fri Jul 17, 2015 10:22 pm

So, the story continues....

I bought a set of Magnecor leads, cap and plugs from Sue Miller. Spark tester shows strong spark in all four leads now. Job done!

Only confusing thing is this:

Magnecor leads come pre-labelled for the four cylinders. I have no doubt these labels are correct. But they aren't the same as my old cap!!!! The firing order is correct, however the terminals are rotated by 90 degrees around the cap!!! In other words terminal one is the next one round the cap, and so on. If I fit the leads according to Magnecor's numbers the engine will not fire. If I fit them to the same cylinders as my old cap, engine runs pretty good!

Does this mean the dizzy is positioned incorrectly?? I have electronic ignition.

The car runs ok. Should I be bothered?

Very many thanks for any sage words of wisdom.

Andy
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PostPost by: UAB807F » Sat Jul 18, 2015 5:35 am

Hi Andy,

The manual gives instructions on how to fit the distributor body although apart from the obvious reason of the leads not reaching the plugs if you fit in certain positions I'm not sure the orientation matters, only the relationship between firing #1 and the crank/valve/cam positions. However that's not something I've ever tried so it could be complete rubbish !

Fitting from the book....

1. set the engine to #1 TDC firing position.
2. fit distributor with low tension terminal adjacent to engine block with the rotor arm positioned towards the rear clip.
3. as the gears mesh the rotor arm should go clockwise to the #1 electrode in the cap.

I think the last time I did it I had the rotor arm just past the clip, say between 9 & 10 o'clock and it aligned ok.

I have had it wrong before, fractionally too low so it picks up with one "tooth" too low and hence the rotor arm doesn't get as far as #1. You can still run the engine but have to rotate the body more to get the timing correct and it looks "wrong". (it also didn't fire up first time, which should have given me a clue..... :oops: )

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PostPost by: EPC 394J » Sat Jul 18, 2015 12:10 pm

Hi Brian, and thanks very much indeed. I'll assume no real problems letting it run like this for a little while then. Will get round to re-positioning the dizzy when time allows.

Regards

Andy
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