SPARK PLUGS!!

[Dragos Nedu]

‘Afternoon fellas, bumped into this topic while searching for possible reasons for a rough idle that my rs is experiencing (no matter if cold or hot). This is my first post, so I apologize in advance if this is not the right topic for my post.

The car is stock, i have changed the spark plugs with OEM ones about 4k miles ago, in a Ford dealer service, as the car was still under warranty. The old ones (or at least the one from cylinder 4) was very dirty, covered in soot. This triggered several misfires, resulting in CEL on. After changing the plugs, everything was smooth for about 2k miles, and now the issue re-appeared (without any noticeable misfires shown on IDS). Went to the dealer 2 times, they cannot find any possible issue with my engine.

I will remove the plugs in the next days, to see if they are (again) dirty, but in the meantime do you have any idea what could trigger this?

2 things to mention:

• I only use high octane petrol (99, in Ro)
• cylinder head was entirely changed during recall (about 2 years ago)

Many thanks in advance! Cheers!

[bobcat]

@Dragos, just a suggestion replace the fuel filter and make sure the plugs are clean. Then see if you get rough idling.

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Honorary Member

 

[Dragos Nedu]

@bobcat, Many thanks for your quick reply – will do that, was going to change the fuel filter soon anyways. Just ordering one now 🙂

Cheers!

[GM]

Check the BOV if i adjust the spring pressure incorrect of my turbosmart one it affects idle… if yours is standard it could be on its way out??

[Defoe18]

Brembo, your plugs look a lot better than mine 🙁

[frenk]

@Brembo: I experienced a strange phenomenon starting last November or so. After every full refuel (Shell V-Power 100) the engine wouldn’t ignite. It took several long attempts (10 sec) and a good boot to start her and have her finally spluttering on.

I mentioned this to the master mechanic before the 6th service (120,000). He said the spark plugs were completely black and he replaced them. He argued that possibly I would drive the car to often like a diesel at 2000 rpm while commuting. However, the fuel mix from the Revo Stage 1 map was too fat and required harder driving.

Don’t know if this is a good explanation, but the strange behaviour after refuel has disappeared.

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Revo Stage 1 – JCR super low seating frame – Mishimoto gas pedal spacer – DSC sport controller

[Defoe18]

That sounds like mine, covered in black soot

[Author]

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