R56 MCS - N18 engine erratic idle

[Craig_P]

Have a 2011 MCS with the later N18 engine, however it has started to develop a few issues in the last few days.

Firstly I get a rattle from the engine between 2500 - 3000 rpm particularly when cold but then disappears when the car is warmed up. Noise only occurs when the car is driven and not when you rev it when stationary.

Second problem that has now occurred is the erractic idle which happens both when the car is stationary and under load. Strange when driving as it is as if the accelerator has a mind of its own. I have taken a video of the car when stationary and the engine warmed up after a 25mim drive;

https://www.youtube.com/watch?v=bPSdBNlAqDU

https://www.youtube.com/watch?v=bPSdBNlAqDU

Has anyone had any experience of this or can suggest the potential issue?

Thanks,

Craig

[DigitalLemming]

Not sure what could be causing it, sorry, somebody who's more technical will be along in a bit.

I've fixed the video embed though, I knew what was causing that problem at least!

[Mon the fish]

I'd guess at MAP sensor but get a code reader on the OBDII port and you'll know better

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[Craig_P]

Thanks both.

I should have also mentioned that the car has not yet thrown a fault code which may make it more difficult to pinpoint the issue at this stage.

[Mon the fish]

You won't get a fault code for the noise I would suspect, but should do for the erratic idle.

It may not trigger a warning light, but there should be a code logged in the ECU

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[Craig_P]

You won't get a fault code for the noise I would suspect, but should do for the erratic idle.

It may not trigger a warning light, but there should be a code logged in the ECU

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That's good to know, I was assuming the EML would have to trigger before the codes were logged.

Thanks