Misfire on Ka

The plugs on these 100yr old pushrod engines are notorious for seizing in, try some penetrating oil/WD40 the night before you want to remove them & you should be to free them by the morning

It is very easy to crack the ceramic of a plug, when this happens you get all sorts of misfiring, so first step is replace the plugs. then leads, then coil pack.

Ah, that sounds like a plausible explanation ;) I'd be surprised if it was the coil pack though given that I didn't go near it :)

Thanks,

Peter.

OK, might just do that :)

Thanks,

Peter.

Trouble is that one HT fault can and does induce other faults (especially with modern supervoltage systems)!! EG: It is very common for people to fail to fit the ht leads correctly on Mondeos, this causes the need for a huge spark which then tracks elsewhere and burns the coil pack, so good luck.

It is quite surprising how much effect a cracked plug has, I did it on a pinto cortina years ago, it seemed ok-ish for a mile or two then started all sorts of coughing, running on three etc. it doesn't just stop running, it nearly runs, which feels worse!

Mrcheerful

This was caught very quickly and it's only been driven a mile or two in that state, enough for the problem to exhibit itself and then for us to return home.

Yeah, it runs fine if you ignore the heavy judder, lack of power and strong engine braking effect :)

Peter.

1) You don't need to remove the spark plugs to do the valve clearances. 2) The misfire is most likely due to you incorrectly setting the valve clearances so it's either not opening or isn't closing when hot.

You do need to remove them if you want to turn the engine over easily. Plus I wanted to check their condition.

I haven't set them yet.

Peter.

Try some oil around the plug the night before and also try removing the plug with the engine HOT.

It's because they seize in place. They have a 30,000 mile replacement but I utterly recommend you at least have them removed every 10,000 miles, ideally every 5,000 come to think of it.

I did this with me-laddo and the sparkies never stuck fast...

That seems like a good plan :)

I replaced them all this morning which appears to have fixed the misfire, 3 of them were tough to get out, and the stuck one was impossible still with my normal ratchet despite spraying penetrating oil round it last night. I had to resort to my breaker bar and it resisted all the way out. Turns out it may have been cross threaded, there's a significant break in the thread on the plug. Should I be annoyed with the garage that serviced it last? New one went in fine so I guess that means the thread on the head wasn't damaged that much.

Thanks,

Peter.

Maybe! It depends if they are supposed to inspect the plugs in the service history. I asked mine to do it anyway... :)

Or at all...

The plugs were changed at the last service by them, I reckon that means it's their fault :)

Yeah, it's not leaking round the edge so I think I/they got away with that ;)

Peter.

Right, it could be. I guess that may depend on what plugs.

Now some of the Ka Klub monkeys swore that XYZ ABC "high performance" plugs changed every 5,000 miles made all the difference, but it's snake oil. Ford's sparkies work just grand in the Endura-E. Kermy, subject to track days, drag strips, nav rallied, rolling roads etc. had no misfires, no nothing and simply had OEM plugs fitted every 30,000 miles and checked every

10,000 miles.

Ford dealer, standard Motorcraft plugs.

Yeah, I always buy parts from Ford now :)

Thanks,

Peter.