Engine hunting?

[Cavey1638]

Hello All,

My 2010 35i had a slight hunt. When the engine was on tickover would vary by about 100rpm. I have just changed all the plugs and some did look a little on the black side.

See pics. Although what a nice engine to work on.

What should I be looking at next. This does not happen all the time. The car has good service history and is on 71k miles.

Also more good news no oil anywhere on top of the plugs.

Thanks in advance.

Cavey

[B21]

Hunting on N54s is often caused by inlet coking which can occur from around 35k miles onwards…

Fresh plugs correctly gapped is your next option

If yiu are unlucky it’s an injector or two..usually plugs are wet then..

[Cavey1638]

I have done the plugs and it seems better. On injectors my assumption if there is an issue would the ecu store a fault code? Also is nitrogen treatment any good for decoking?

[B21]

I have done the plugs and it seems better. On injectors my assumption if there is an issue would the ecu store a fault code? Also is nitrogen treatment any good for decoking?

Generally the injectors don’t generate many fault codes on this early design of direct injection..even later injectors are generally not very helpful in flagging faults..

I used walnut blasting for mine…I don’t have experience of any other inlet cleaning product…