Need Help Sudden Increase Fuel consumption e38 740i

[ETATD]

Dear all,

Bit of a first time user I'm 24 love bmw e38s this is my second one and I want it to last for ever. Driving across Europe next week and whilst driving it today I noticed a sudden drop in indicated fuel economy. I usually get 17-18mpg as it's a 2001 740i M SPORT but recently intercity I am getting below 12. I don't know what it could be, it drives fine starts fine and sounds fine but something must be wrong? Anyone have any ideas?

Car has just been serviced full oil change and filter inspection 1 at 118000miles Last service was inspection 2 at 108000miles.

[ben4bama]

Pcv or ccv (whichever your car has) valve gone bad

[pizzaman09]

A drop in fuel economy on an M62 engine is often a sign of a bad MAF or pre cat O2 sensor.

[BimmerBreaker]

Yeah my money would be on MAF. I'd imagine a bad CCV/PCV would cause an increase in oil consumption

[ETATD]

Dear all,

Thanks alot for all your help, thats great will look into getting it fixed before setting off. Will try pcv/ccv first then clean Maf and if all goes Pete tong, I'll change the oxygen sensors.

Thanks again for the quick replies.

[ben4bama]

Dear all, Thanks alot for all your help, thats great will look into getting it fixed before setting off. Will try pcv/ccv first then clean Maf and if all goes Pete tong, I'll change the oxygen sensors. Thanks again for the quick replies.

If O2 were bad it should throw a code. Just search for symptoms of bad Pcv and ccv and you'll see that besides it consuming more oil it will also dramatically increase fuel consumption. I just replaced the Pcv on my wife's car and it fixed both of these symptoms. Good luck.

[BimmerBreaker]

O2's and MAF's dont always immediately throw a code. I'd start with the MAF/O2's personally, as PCV/CCV usually has other symptoms but do what you will. You can diagnose the MAF for free, but it sounds like you are about to start just throwing parts at the car...