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Hey fox, hope you are doing well.

I have a question for you about coil ignitir because it's a well know part that could fail on some engine from VAG.

I'm running my 6C for now almost 3 years and it has 125600 km or 78000 miles.

Spark plugs have been change two months ago but some time engine is jerking on idle. It's completely random (hot/cold engine).

This is the coil igniter model I currently have: Original ones because VW change for an other Part Number: 04E905110P

My OBDeleven record some few missfire on all pistons but nothing to worry about because on full throttle and daily drive the car feels nice.

My engine is a 1.2 TSI 90hp CJZC.

If you have some kind of tips, recomandation etc...I'm open.

Hmm... install Original spark plugs purchased from a VAG group dealer or high quality spark plugs in high prestige stores.


Never buy them at low cost where we ali know... jerks or misfires are guaranteed.

Yup, but at 60 euros the coil ignition: it's quite expensive :v

If I buy it will be ELDOR (original brand put on my car) or BERU.

I heard that NGK had many issue.

Bosh could be a good option, they are OEM on BMW.

My advice/tip is more directed to the 'spark plugs', since after the replacement of the spark plugs the symptoms and the diagnosis that you mention began, right?
, as you already know, there can be many other causes for these symptoms (coils, coil connectors, wiring, fuel, etc).

Another tip is that you check the correct/perfect installation of the coil connectors and clean the coil connectors with zero residue contact cleaner.

ciclo wrote: Fri Mar 31, 2023 7:19 am My advice/tip is more directed to the 'spark plugs', since after the replacement of the spark plugs the symptoms and the diagnosis that you mention began, right?
, as you already know, there can be many other causes for these symptoms (coils, coil connectors, wiring, fuel, etc).

Another tip is that you check the correct/perfect installation of the coil connectors and clean the coil connectors with zero residue contact cleaner.

Since I have the car (for almost 3 years) she always did that. Sometimes engine is jerking slitly.

But performance are good, I did againt today a full throttle acceleration and not issue at all.
It's just sometimes at idle.

I will see to clean contactor with a dedicated product.

Connector on both side cleaned with a contactor cleaner. Little bit of dust.

Start the car, running smooth but the engine was hot

I would hope that if this was a coil issue, then a proper scan tool would provide details as to which cylinder coil or cylinders coils were causing a spark plug firing to be missed.
These coils do not have a recommended service life, so they only need replacing when they or one of them has failed and this is getting recorded by the engine controller.
Also, I seem to prefer Eldor as a coil manufacturer.
As said already, this could be spark plug failing to fire, they need replacing every 4 years or maybe 60k miles.
Finally there can be other reasons why a cylinder misfires at light load or lower throttle openings, for instance failing injectors or failing Lambda sensor, the control one is the one nearest the engine end of the exhaust system.

RUM4MO wrote: Fri Mar 31, 2023 5:02 pm I would hope it this was a coil issue, then a proper scan tool would provide details as to which cylinder coil or cylinders coils were causing a spark plug firing to be missed.
These coils do not have a recommended service life, so they only need replacing when they or one of them has failed and this is getting recorded by the engine controller.
Also, I seem to prefer Eldor as a coil manufacturer.
As said already, this could be spark plug failing to fire, they need replacing every 4 years or maybe 60k miles.
Finally there can be other reasons why a cylinder misfires at light load or lower throttle openings, for instance failing injectors or failing Lambda sensor, the control one is the one nearest the engine end of the exhaust system.

On OBDEleven you can see all cylinders missfire. It's like a counter.

Car is daily drived at 90% on highway. Only weekend few kilometers on city but over 400 on highway each week.
So I don't think engine is dirty.
The gap for the spark plug (brand new) is about 0.7mm.

However, injectors have been never cleaned (ultrasonic for exemple).

Missfire count on OBDElven since the begening of the life of the car:

I'd still think that something else is causing these missfires, but I can't say what exactly.

The only thing that I can think of that might cause these coils to missfire, could be the earthing lead that is associated with the coil firing cableform, I seem to remember that there is a heavy brown lead connected to the cylinder head, if I am correct, is it still looking okay?

This is the Wiring Diagramm od my car:
So yes, I have to check the wire "15", at least, the state of the ground connector.