Pinking/valve rattle on Ford Focus (1.6 zetc V-Reg)?

Question

A couple of weeks ago I noticed a missfire after leaving the motorway and drove like this for around 10 miles home. My diagnostics involved removing plug caps and I found that removing cap 2 had no effect (mis-fire stayed the same). Replacing the coil pack resolved this and the mis-fire is gone.

However, since this I have a horrible valve rattle (That is what is sounds like to my dumb ear) at around 4k revs, any gear. It is worse under load but is there even cruising on the motorway. Have had it at a Ford Dealer twice. First time they loaded the latest Ignition software - no effect. The second time they say that reprogrammed the fuel system - no effect. Now they say that I need a "liquid de-coke"

I think that they are clutching at straws but would be interested in other's views.

There does not appear to be any loss of performance or economy but I am worried that it may be something serious and is not a true pinking at very low revs.

Any ideas?

Cheers

Wayne

Answer 1

You won't say Cheers after this answer. Mechanic Wolf licking his lips. Misfire causes the cat converter to over heat that causes the ceramic elements inside to break and rattle. Try hitting the exhaust with a soft mallet hear if you can rattle the converter nearest the engine. Or some times heat shields on the exhaust get cracked or loose. If the converter is broken do not drive the car hard because some times bits and pieces get blown back into the engine. Replace converter right a way.

Answer 2

I have had trouble with Ford before.
We dont get mechanics any more we get technitions who can only plug the car into a computer in the hope it will tell them whats wrong.
If your car has been running on a missfire for a while then there is a possibility that it has damaged the catalist, mainly because unburnt fuel get to the cat and destroys the element.
It could also be the oxygen sensor being damaged at the same time.
I would say its possibly a mixture of both.
I have had what is called pinking on cars before and it is usually caused by the fuel mixture and not mechanical.
Ford can be pretty much clueless so I would take it to a performace centre to get it rolling road tested.
Having a faulty cat and or oxygen sensor will cause the car to readjust the fuel/air mixture.

Answer 3

Running for a while with a misfire could have allowed a carbon build up on the valves/plug on cyl 2

The old cures are often best

Give it a hard run on the motorway (a good thrashing normally blows away soft build up).

Liquid decoking is little more than pouring red-ex or equivalent into the air intake on a hot and high reving motor.
Clouds of smoke but cleans the cylinders.

PS
Your description does not sound like pinking (normally only under heavy load in high gear)

Other possible sources include dry cam follower (normally hydraulic type)

Does it go away if you remove plug cap 2 ?

Answer 4

Funnily enough I'm having the same problem.
My local dealer ran a diagnostics check, but couldn't find anything wrong.
They did tell me the old mondeo's used to suffer from " under bonnet heating " which made them engines pink. But weren't aware of the focus's doing the same.

As no fault was found I was told there was no need for concern ?????
I'm still not convinced though !!!!!