1.4 mpi firing on 3 cylinders - missing a spark plug

[neilfitz]

First off, it' s a 1.4 mpi Aqw engine (i think ) with 188 k on the clock. So its not a new car. Swmbo took it out for a spin this after called me at home to say i think the skoda's finally died, making funny noises, loss of power and so on.

I go out to meet her and we manage to coax the car back home, some 10 miles. Almighty noise coming from the engine bay, sort of rythmic hissing, slapping, bangin - thought is this the head gasket, cracked block or just exhaust manifold?

Car drove at road speed but i took it gently, noticeably down on power, alot more revs to get it going also when the clutch was pressed in the loud banging noise stopped, until it was let out again.

Got it home with a splitting headache and up on ramps to peer underneath, no sign of any noticable damage. It was only when i got under the bonnet and took off the plastic cover i noticed one of the spark plugs was missing. I removed the 'coil pack' and the last rubber socket was missing, looked like it had been torn off. And a hole where the spark plug should be in the last cylinder, marked no 3. Found parts of the spark plug in the undertray - the ceramic part. And threaded end. Assuming that explains the hissing noise air escaping through open cylinder!

My concern is parts of the plug might have dropped into the cylinder. However what i noticed is there was no threaded element to the spark plug hole and when i offered up a spark plug to it the plug slipped in quite easily, assuming there is only a Threaded insert in the hole to take the plug - is that whats known as a helicoil

In a nut shell, is this repairable. My initial thought is to replace the coil pack with a second hand unit for about 25 quid, but what can i do about the thread on the spark plug hole, or lack of? Is it a diy job, just an insert a new one, whatever theyre called, or do i have to bite the bullet and throw cash at the problem?

I am annoyed with myself because i had done a diagnostic reader some weeks ago and was showing up miss fire on no 3 and cross referencing here a lot of suggestions where try a new spark plug. There has been a noticable lack of ommph but again its an old car and the mpi engine has never been that quick and it was livable with.

Then of course there is the risk of debris in the cylinder itself... I guess that would be a garage job, and then the cost of stripping down would probably start to outweigh the value of the car.

This happened to anyone else?

Still, says alot about the mighty little mpi unit.

Cheers

Neil

[Breezy_Pete]

I doubt that anything of the spark plug will be inside the engine. The whole thing sounds like it got fired out of there at speed, so can't see why it would have left any bits behind.

It may well be repairable with a helicoil. Is there a trusted garage within limping distance? 

 

Originally the thread for the plug would have been cut straight into the head, I think, rather than there being any sort of insert, but it may have previously been repaired with a helicoil.

[neilfitz]

Thanks. Thats reassuring. Yeah we have got a good indy up the road , might have to invest in some ear defenders first, my ears are still ringing, best noise the little cars ever made!

[TMB]

What a bizarre thing to happen!   If it can't be repaired it'll need a replacement head, assuming there's no piston/cylinder damage.

[Alexandru]

I assume that spark plug hasn't been fixed correctly (loose or too much torque involved). In both cases, I'd check and double check for any head damages that might have been caused.

[cxprestigeauto]

I can do you a good deal on a good head and a replacement coil pack.

 

PM me for details.

 

Rob

[KenONeill]

This sounds like a classic "failed Helicoil" case. I'm not sure you can actually fit another Helicoil if so, which would mean a new head.