2007 bmw 320 diesel - Sudden excessive fuel consumption

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Fri 13 Jan 2012 13:37
2007 bmw 320 diesel - Sudden excessive fuel consumption - bobap

My bmw 320d was unused for a month whilst I was recovering from surgery. Since starting to use it again the average fuel consumption over my typical mix of driving has increased by 10mpg from the figure it has been over the last 4 years. I've checked for binding brakes, no problems there and the performance is unaffected. Any ideas on the cause of the increase in fuel consumption most welcome please.

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Fri 13 Jan 2012 14:31
2007 bmw 320 diesel - Sudden excessive fuel consumption - Peter.N.

Any black smoke from the exhaust, auto or manual?

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Sat 14 Jan 2012 10:41
2007 bmw 320 diesel - Sudden excessive fuel consumption - dervdave
How

Edited by dervdave on 14/01/2012 at 10:44

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Sat 14 Jan 2012 10:45
2007 bmw 320 diesel - Sudden excessive fuel consumption - dervdave
How are you measuring the mpg ?

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Sun 15 Jan 2012 09:17
2007 bmw 320 diesel - Sudden excessive fuel consumption - bobap

Using the computer mpg readout.

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Sun 15 Jan 2012 12:47
2007 bmw 320 diesel - Sudden excessive fuel consumption - dervdave

Using the computer mpg readout.

Does it confirm your actual usage, because they can be way out for a variety of reasons.?

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Sun 15 Jan 2012 09:16
2007 bmw 320 diesel - Sudden excessive fuel consumption - bobap

Thanks. No black smoke. It is a manual.

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Sat 14 Jan 2012 12:06
2007 bmw 320 diesel - Sudden excessive fuel consumption - xtrailman

Maybe check the tyre pressures.

Does the car coast ok?

Also are you allowing for the colder weather, my xtrail gearbox was noticably affected by the cold temperatures yesterday.

Edited by xtrailman on 14/01/2012 at 12:09

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Sat 14 Jan 2012 15:17
2007 bmw 320 diesel - Sudden excessive fuel consumption - Peter D

You need some diagnostics and live data, you may have a failing MAF and the car is slightly overfueling. You also need to ensure the ECU is seeing the correct engine temperature. Regards Peter

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Sun 15 Jan 2012 09:18
2007 bmw 320 diesel - Sudden excessive fuel consumption - bobap

Thanks, I've tried coasting and it seems ok.

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Sun 15 Jan 2012 13:35
2007 bmw 320 diesel - Sudden excessive fuel consumption - dervdave

Does it confirm your actual usage, because they can be way out for a variety of reasons.?

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Sun 15 Jan 2012 14:22
2007 bmw 320 diesel - Sudden excessive fuel consumption - bobap

Amount of fuel to refill to full against miles covered since last filled seems to tie in with a signifcant drop in mpg. Looks like I'll have to visit my local independent bmw guru for some diagnostics. Cheers.

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