Misfire

[chrishewett]

I had an intermittent misfire which has now become permanent.
I have just replaced the plugs and it is obvious that number two is dead. (when I remove the lead there is no change in engine speed). Does this point to a lead or could it be a coil even though only one plug is not firing.
It is getting a bit expensive to just replace everything!
Thanks,
Chris

[GeoffSmith]

Chris, the ignition is a 'lost spark' system so plugs 2&3 both are fired together from the same coil, so it is likely to be the plug lead or (less likely) one side of the coil. You can obviously swap the leads over at the plugs and/or coil end to confirm whether it is the plug, lead or coil at fault.

[RayD]

Chris,

It could be a faulty new plug, change two of them round or No. 2 with one of the old ones.

Ray

[GeoffSmith]

Ray, my thinking was that if a lead or the coil was going down, then replacing the plugs could result in the temporary recovery that Chris has seen, only to be followed by the same problem re-occurring as the source of the problem worsens.

Chris, I seem to remember you had major engine work done - it may be that coolant has been dropped onto the coils/leads when the header tank was removed. A bit of time in a cool oven (while your wife/girlfriend/mother/partner are out shopping of course) may help.

[chrishewett]

Thanks for the replies.
Yes I have just had a major engine and gearbox rebuild.
The leads do look in bad order so I think that I will have to spend out again and order a new set. If the problem is still there after that I will look at the coils.
Any suggestions as to where to shop for leads?
One day I might get a proper drive in this car!
Chris

[GeoffSmith]

There's a group buy going on here and if necessary coil packs here.

[firebobby]

Chris. Check this out on e-bay. 120290228811 It's not leads but the guy who is selling it is breaking an elan. I'm sure (martin....his name) will have the leads available. Give him an e-mail

[chrishewett]

Hi,
I just had a new set of leads delivered from magnecor. They are fitted and the problem still persists. If I hold the number 2 lead to the plug I can hear it sparking. I am beginning to think there could be a more serious problem than ignition.
Any suggestions.
Chris

[firebobby]

sounds like a compression test would be in order!!
dave

[RayD]

Chris,

Have you tried changing two of the plugs over in case one of the new ones is faulty?

Ray

[chrishewett]

I have just done a compression test and it shows 165 on all four. Changing the plugs has made no difference.
I suppose a coil must be faulty.
Looks like new MSD coils will have to be ordered.
Unless anyone has any other suggestions?
Chris

[Sy V]

At this juncture, it's the most logical step, Chris.
Let's hope that fixes it.

[M100 TWO]

My money is on a new coil a knacked one will still give you a spark but it wont be enough at the plug tip under compression
diff

[chrishewett]

Well, after new coils - same problem. I took the car back to the guy who rebuilt the engine and the problem turned out to be caused by a bad connection on number two injector!
I am glad I changed the coils and leads as they were old so all is well that ends well.
Chris

[rip]

Glad you got it sorted...




...& saw the positive side of renewing your ignition system too.