E91 320D Mpg Why So Poor

[Gaz.s76]

I brought the bmw thinking be good a fuel not getting above 40mpg and a use to get 34mph out of my Ford Focus ST 2.5 turbo on a run why is it so low bmw has full service history last service 2 months ago

[Guest jeffthro]

You're quite right, Gareth, that does seem on the low side. Last service definitely done OK? Suggest an engine management check see if any messages come up.

[Gaz.s76]

I've done a check says all clear plus last few morning runs really rough till give it some throttle then is fine it's a auto but should get more mpg than I am plus having problem with heating only can get red hot

[Gaz.s76]

I've done a check says all clear plus last few morning runs really rough till give it some throttle then is fine it's a auto but should get more mpg than I am plus having problem with heating only can get red hot

[Guest jeffthro]

Heating only red hot? Is the engine running at normal temperature, needle vertical on the gauge? If the engine is running hot your thermostat is stuck, if running normal, theres something in the heater unit, name of which escapes me, another thermostat type control gubbins which has packed up. Sorry, bit vague there!

I've got the opposite at the moment, my thermostat is jammed open so engine runs cool all the time and heater only blows warm at best.

[Gaz.s76]

No temp gauge on my dash don't know why I don't like that it hasn't. Heating seems ok again now must me a itamitant fault. But fuel economy very poor

[Guest jeffthro]

Just read the other thread you've got running, Gareth, yes, I reckon its that hedgehog resistor thing. Do a PM to DIZRAN as he seems to have had experience of the same thing?

You see, my description of another thermostat type control gubbins was quite good, compared to telling you that you needed a hedgehog! :rolleyes:

[mikesmith2939]

The hedgehog only controls the fan speed, when it fails the fan continues to run even with the ignition off.

You'll know when it fails because you will constantly get a flat battery.

Try a few bottles of injector cleaner to clear some of the crud, also a good hard blast down some fast roads will also help clear some of the soot especially if it's only been driven around town most of it's life.

As for the heating do you have the digital control or dial control?

[Guest jeffthro]

Oo Er! Mikes' taken it on to another level there, so I guess that means..................I'm out. :wacko:

[Gaz.s76]

I have the digital control on mine. Heating seems to be working again at the moment but it's all very annoying

[mikesmith2939]

Have you tried a hard reset of the electrics?

Disconnect the battery touch the two battery cables together for a couple of seconds, this resets all the computers on the vehicle except the security system.

It could be some electrical glitch that will right itself after this.

[xxXxx]

My previous E90 had a poor MPG when I first had it, low mileage and full service history, changed both thermostats and it improved greatly. There is a hidden menu you can access to check the temperature whilst driving, if you google it you should find a guide.

[iain1969]

Hi, I have an e46 320d 2005 over 40 mpg round town, short shift it will take it and lift foot off the gas a bit this makes no difference to the performance otherwise clean the DPF valve turn off the EGR if you have the money get an ecotune front pipe this will improve the mpg a lot.

good luck.

iain1969

[iain1969]

try a ecotune front pipe, turn off the EGR valve short shift it will take it and don't use so much loud peddle check all filters and get a remap the difference is great.