Well the car went into the dealer for a lumpy idle, they changed the plugs and all was good for a few weeks.

Sat at some traffic lights in N and the revs raise and drop and shudder through the car, it drives smooth though.

Went back in today and try have changed the plugs.....again.

Anyone know what the cause is?, first time one of the plugs was 'deteriorated' this time

I don't know yet.

Cheers

How old and how many miles on the car.

Has it been plugged in and checked, has it had any ECU update?

Maybe it needs Coils.

Maybe it needs checked by someone that knows about Twinchargers.

You would hope that is a Skoda Dealership,

can you try going to another one and get your Warranty work done if required?

george

If the wrong plugs are fitted to a Twincharger engine, then will show signs of overheating and last upto 1000 miles. Took several sets and a half-engine rebuild for VW to realise they were specifying the wrong ones for the Scirocco (until mine..then the VW parts system was updated to issue the right plugs, as per other twincharger engines). VW lost a few engines to that mistake.

In your case, it does sound like coil packs though? Could possibly be injectors though causing a weak mixture.

Nearlly 15 thousand in running on 95 the whole time the orginal plugs are still going well, there's slight build up but nothing major

18k it's 16months old. I would hope I don't have to tell them to change the coils/injectors but they haven't said they're going to.

Apparently they have done an Ecu update today. Don't know why it wasn't done last plug change.

Ill see what they say tomorrow and ask them to do coils see what they say

They can not just do them, they need approval, Skoda will be paying, it is a Warranty Claim..

That means it needs a diagnosis.

They seem a bit 'trial and error' in their approach.

I take it you have not paid for these plugs?

What has the car had done, a 12 month/10,000 mile service?

The Upgrade should possibly have been done then/

** Ask tomorrow what plugs they fitted/removed, & what plugs they fitted now.**

Get the number from them.

(i would not accept the answer, 'the correct ones'.

i would want the Tech that did them to tell me)

george

Yer I'm pretty sure it was diag'd but not positive. It seems mad that a set of plugs can need changing after 3 weeks, can't be the right ones.

And sorry no, haven't paid for the plugs. Don't intend to either

And it had an oil change at 9751, then one 7 months later at 14686.

plugs you want are : 03C 905 601 A (VW part number)

Just keep driving it... It will blow a cylinder soon Nd you will have a new engine

I did.

Thought I'd update the situation for people comming across this thread. As above its blown cylinder 2.......no compression in 2 compression leaks in all 4 cylinders and oil comsumption issues.

New engine being fitted tues.

Hopefully problem solved

So much for the ability to diagnose the simplest of problems... better to wait for the engine to disintegrate :(.

No problems with diagnosis then I suppose...

Spark Plugs could be very effectively used to diagnose and understand combustion conditions within a cylinder.

When plugs are virtually eaten away within few weeks and all they can do is to put in new ones they have to have no fecking clue what they are doing sadly...

The problem arises, Jab, when it's warranty work and VAG HQ are involved as the techs have a look, tell VAG what they find and wait for VAG to say what they'll pay for next. Even if the guy/gal working on it does know their stuff, their hands are tied by those holding the purse strings.

In defence of the plug issues I had, VW Stoke were only allowed to fit what VW UK would pay for. Only after the random replacement of the injectors, coils, ECU, a piston and a cylinder head did they let the tech offer his suggestions - and that was that the plugs fitted at service time were overheating, causing the misfire (and subsequent engine damage). Turned out the wrong plugs were spec'd to be fitted..

If Skoda say "fit another new set of plugs" several times, that's all the garage CAN do AND get paid for it.. Now they get an engine change out of the deal.

Phil, that sounds like well made argument. Form SUK's financial point of view however it holds no water. They have no reason whatsoever to stubbornly keep telling service techs to do the same pointless replacement and ignore their on the ground advice, assuming that's what's happening. But then again they have to do it by the book as you said...

In your case plugs were overheating as they were too cold thus preventing over rich mixture deposits to be fully burned away. As they started to accumulate they were causing pre-ignition leading to detonation when two flame fronts collided causing destruction of piston/rings. I wonder what plugs my car has?

Pretty sure that for 99% of faults on the cars, they have a flowchart (based on the list of fault codes...but we won't go there). When mine "went", as the fault codes said "multiple misfires" the "book" answer is to replace plugs and/or coil packs. Won't help with a lack of compression...

There's no fault code for red deposits on the ceramic of the plug..with implies too hot a plug, surely? Or am I getting the terminology wrong?

Back to the old issue of "techs" being parts swappers, not fault finders. Too much reliance is put on fault codes; they sometimes only show the symptom, not the cause.

I know I'm sounding like a broken record with the plugs but it was a shocking coincidence that Scirocco twincharger engines started dying as soon as they hit 40k (plugs changed at 38k-ish as they were virtually all on variable servicing ) - or in the case of a couple of cars, bought used with a "full service, sir".. New (factory) engines didn't have the issue, funnily enough.

I have a feeling that the plugs were for either the 1.4 FSI engine or the 1.2TSI that were specc'd, rather than twincharger ones.

Light brown or black is fine. Whether your red is that light brown I do not know, would have to see at lesast a very good photo of the plug, still one needs 4x magnifier and very good natural light to read plugs, They also have to taken from an engine which reached operating oil temps, was revved to max revs and ignition cut there. only then you can read the plug correctly. If plug has boiled ceramic centre lectrode holder, white, powdery deposits on it it is running too hot. I always get confused with terminology as it counterintuitive .

From the description I had from VW, they looked a bit like this (left hand plug);

From here: http://www.ngk-sparkplugs.jp/english/techinfo/qa/q15/images/photo1.jpg