Fuel economy drop on my 3 Series - why?
I have owned an 07 BMW 320D Sport Tourer Auto from new. Until last Autumn, I was averaging 37mpg. This has fallen over the winter to 24mpg in town and 34mpg on open road. There are no significant indications on the fault management system. The BMW agents have suggested replacing the heater plugs and control unit, but cannot be sure this is the problem. Any ideas please?
Asked on 1 May 2013 by DASman
Answered by
Alan Ross
Well having checked the air intake/filter system then the dealership should have carried out a diagnostic check, which should then show up a fault code.
This code should then relate to the problem area. If the dealership are saying there are no codes, then we would have checked the following:
1. FRP (fuel rail pressure sensor)
2. FRP control valve
3. Fuel quality adjuster
4. Injectors
5. Turbocharger(TC) boost pressure sensor
6. TC wastegate regulating valve
7. TC wastegate
8. Exhaust/catalytic converter- restriction
9. ECU programmimg
Rather than just changing the heater plugs (unless they are sure that they are at fault) then we would suggest that the above checks would be carried out in the first instance to establish the reason for excess fuel consumption.
This code should then relate to the problem area. If the dealership are saying there are no codes, then we would have checked the following:
1. FRP (fuel rail pressure sensor)
2. FRP control valve
3. Fuel quality adjuster
4. Injectors
5. Turbocharger(TC) boost pressure sensor
6. TC wastegate regulating valve
7. TC wastegate
8. Exhaust/catalytic converter- restriction
9. ECU programmimg
Rather than just changing the heater plugs (unless they are sure that they are at fault) then we would suggest that the above checks would be carried out in the first instance to establish the reason for excess fuel consumption.
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