really bad fuel mileage

joe_keefer · Post by **joe_keefer** » Sat Feb 19, 2011 10:24 pm

well i guess i have a little work to do. if my math is even close i`m getting about 8 mpg. i know the valves need to be adjusted, i`m pretty sure the timing is still off. i guess i know what i`m doing tomorrow.

what`s a normal, ball park mpg. for a stock 528i? 20-25mpg?

thanks, joe

T.Hanson · Post by **T.Hanson** » Sun Feb 20, 2011 10:46 am

I want to say yes, 20 - 24 on a controlled road trip, but that would be with a total super tune. The truth is, the car runs good. No leaks, oil, coolant smoke, timed right, accelerates well.

Put in gas. Drive. When needle is low, put in gas.

Keith · Post by **Keith** » Sun Feb 20, 2011 7:34 pm

A few things to consider:
1)If you have a colder than stock thermostat, this can often cause the ecu to stay in warm up mode, increasing your fuel consumption. You can test the stat, or just the water temp with a thermometer to see if your getting 80 Celsius.
2) Your temperature sensor for the ecu may be malfunctioning, causing the ecu to again stay in warm up mode
3) After the car has been running for a while, take out the cold start valve and see if it's still on/leaking fuel. A faulty thermo time valve can cause this, or a bad cold start injector.
4) Double check your timing, making sure you're checking it at 2200 rpm.
5) A bad fuel pressure accumulator can create higher than normal pressure in the fuel system, increasing fuel consumption. If you detach the vacuum line and see fuel leaking from there, this can indicate it is faulty. Best bet, though, is to get a fuel pressure gauge hooked up and see where you're at.

That's all I can think of off the top of my head.

Mike W. · Post by **Mike W.** » Mon Feb 21, 2011 4:37 pm

Driven moderately a 528i should get 19-22 or so. If it's far off that something's very wrong. Anything from FPR to FI temp sensor to AFM or even a plugged cat.

socalfiver · Post by **socalfiver** » Thu Mar 03, 2011 8:59 pm

My '80 Automatic turns in 15mpg consistently, regardless of driving style. I would love to get 20, but have adjusted everything I know to adjust.

garyinwestoz · Post by **garyinwestoz** » Fri Mar 11, 2011 9:36 am

city driving i get about 300 km from 45 ltres @ 0- 80 km/hr speed

country trips I can get upto 500 km @ constant 110 km/hr

Troy · Post by **Troy** » Fri Mar 18, 2011 2:13 am

FWIW, I chased a fuel consumption problem for about year. Did a lot of work -- plugs, wires, vacuum hoses, AFM recalibration. I finally discovered that the real problem was the trip meter (and odometer). It was registering about half the miles.

So, if I were you I'd go out on the interstate and count mile posts and compare that to the recorded mileage.

On the plus side, the car ran really well after all that work.

Blaise · Post by **Blaise** » Fri Mar 18, 2011 10:54 am

Troy wrote:FWIW, I chased a fuel consumption problem for about year. Did a lot of work -- plugs, wires, vacuum hoses, AFM recalibration. I finally discovered that the real problem was the trip meter (and odometer). It was registering about half the miles.

So, if I were you I'd go out on the interstate and count mile posts and compare that to the recorded mileage.

On the plus side, the car ran really well after all that work.

Good point. Mine did the same thing. Another way check you mileage is to use google maps.