Ford KA choked and running on three cylinders (petrol)

My daughter has a Ka 13i (OHV) its on a S plate (98) its started playing up. The faults a bit awkward to describe but basically the engine sounds like its choked and running on three cylinders (I.E. its running rough). I use to know a lot about cars in the early days but the setup today beats me, ive had a quick check for air leaks as I first suspected an air leak. The cars not really worth a lot but I was hoping she could get about another ten months out of it as the MOT will be out then. anyway if any body has suggests I'd appreciated any help.

SB

Reply to
soundboy
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plugs, leads, coil pack,

Reply to
Mrcheerful

mmmmmmm tried plugs, never thought of coil pack n leads is there a way on checking the coil

SB

Reply to
soundboy

the coil pack burns internally. using a spark gap tester on the cylinder that doesn't run (best found by shorting the plug top to earth) should show it up . the plugs are fired in pairs (1 and 3 and 4 and 2 IIRC) so you can swap leads around and see if the fault moves with you

Reply to
Mrcheerful

I changed the plugs now, it was still rough but it went a little better, but the problems still there. I'm assuming the coil works off a wasted spark system but I'm not familiar with these systems at all. Today I investigated a little bit more - I pulled the leads off one at a time as suggested and noticed NO spark on pot 3 - so I swapped 3 & 4 pot HT leads around and there was still no spark on 3 - but I'm not sure how the coils work, in my head I see 4 coils in one pack - so I'd assume 1 part can go faulty but I have a feeling I'm missing something here.

SB

Reply to
soundboy

Yes, one plug will spark and not be doing anything, while the other is actually lighting something. it has two coils (in the one lump) with a plug lead from each end of each coil, so one spark is a positive spark, one a negative. What seems o happen is that one end will burn internally, the other 'half' of the spark will still work, hence even though there are only two coils you can lose one cylinder.

Reply to
Mrcheerful

Very interesting indeed, thanks for the explanation

Reply to
soundboy

OUCH! You were doing well until then and really need to brush up on your knowledge.

Reply to
Jim

That is a cliffhanger! please enlighten me and everyone, I like to gain new knowledge everyday.

Reply to
Mrcheerful

I have my new coil - now is there a firing order - or do I just fit the leads as it says on the coil example:-

coil number 1 goes to plug 1 coil number 2 goes to plug 2 coil number 3 goes to plug 3 coil number 4 goes to plug 4 I've never fitted one of these coils before.

SB

Reply to
soundboy

just as it says 1 to 1 etc.

Reply to
Mrcheerful

cheers - nice and easy - not like it use to be with a firing order of 1432 maybe you are too young to remember

SB

Reply to
soundboy

oops 1342

Reply to
soundboy

uuuummmm, your firing order is still 1342, and I do have 46 years experience (that I remember) Starting on a morris minor, topping up the battery while standing in the engine bay and I still swear the engine was running, although logically I think even my dad would have turned it off.

Reply to
Mrcheerful

yeah I guess what you are saying - but I don't think we have to think about it too much these days firing orders that is. I served my time on vauxhalls vivas, chevette, victors (FE) but had a problem with oesteo arthritis 15 years ago - so had no choice but to leave the car trade behind - which I mis like hell. I still do bits but as you can tell here I'm damn rusty SB

Reply to
soundboy

"Mrcheerful" gurgled happily, sounding much like they were saying:

My old man had me change the end on an extension lead when I was a kid - except he forgot to turn it off at the other end...

Reply to
Adrian

y

(yorkshire accent) Luxury... (etc. etc.)

Reply to
tonewheel

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