MISFIRING

[kevin31157]

Hi guys, back again.
Drove the car for a good 50-60 miles a fortnight ago and as soon as i got home it started to misfire, like a plug had gone down. Then after engine had cooled down about half an hour later i started it and it was fine again. Been running it over the last two weeks locally and no problems. Took it out again on a long run yesterday and as soon as i`d got to my garage at home again, i pulled into the drive and it started misfiring again. I checked the plug leads and noticed that whilst idling and pulling off the leads to the plugs one at a time that plug one and three didn`t idle slower and kept ticking over at the same speed. Two and four plugs did drop to a lower idle speed on removing those leads.
I thought surely i wouldn`t have TWO plugs gone down at the same time. So on putting the leads back on the plugs it was still misfiring and as i drove it up the ramp step into the garage it started running good again all of a sudden. I switched the engine off and put the car away for the night.
I decided to replace all plugs today and once replaced i started the car but it is still misfiring. Any pointers to what it might be chaps?
Thanks,
KEvin

[dapinky]

Kevin,

As the coil packs send sparks to cyl 1 & 3 at the same time, then 2 & 4 on the next revolution, it suggests to me that the issue is with the electrical spark system at the coil pack.....

..... I would suggest that one of the packs is breaking down when it gets hot and no (or a reduced) spark is generated.

This is not an uncommon problem, and new coil packs can be picked up in the UK for a reasonable price (unless you go to Lotus, then you'll pay a premium).

[Rambo]

I would also agree with Dave's synopsis. Good coil packs can be had very cheaply off EBay

[kevin31157]

Hi, dapinky.
Thanks , i have just been going through some of the conversations on the forum about misfiring and noticed somebody had mentioned replacing both coil packs which WILL need replacing sooner or later. Think i`ll order two tomorrow and replace them anyway now i`ve done the plugs already then get it in the garage. Are both packs under the header tank?

[Rambo]

Are both packs under the header tank?

Yes

[kevin31157]

I would also agree with Dave's synopsis. Good coil packs can be had very cheaply off EBay

THanks Rambo, i`ll replace them like you and dapinky suggest the problem might be. Theyve never been done so nows probably the time. Cheers

[kevin31157]

Are both packs under the header tank?

Yes

Great thanks

[dapinky]

Kevin,

You may have noticed it mentioned in other threads as you've been looking, but you will need a specific size of 1/4" drive socket for swapping the coil packs...... many people will tell you that it is a 5.5mm metric bolt, but it's actually 7/32" Imperial (they are so similar that either will work, but I'm just being pedantic!)

[kevin31157]

Hi again,
I have had the car back in the garage and replaced the coil packs and the plugs but it is still running like a struggling pig. Anything else it could possibly be guys?
thanks

[John_W]

Plug leads?
I just replaced my 12 year old Kingsborne wires with a Cambiare set off ebay for £26.70 and it cured a misfire I have been trying to trace for the last year.

[kevin31157]

Are both packs under the header tank?

Yes

Hi again, the coil packs have been replaced and new plugs but apparently the garage says its still running the same, like a pig and like its firing on 3. Any ideas as to what else it could possibly be please/
Thanks

[lotustonybassplayer]

have you checked the fuel injectors

[kevin31157]

have you checked the fuel injectors

No, i havent checked them. What my neighbour mechanic did though is gently push against the top of each injection head at the top and we noticed there was a slight noise difference in the engine idling on number 3 injector whereas the others made no difference in sound whatsoever although it didnt sound that serious to really notice, but it was there slightly.