X5 e53 3.0d - Fuel Range suddenly dropped.

[Salty_Dog]

Originally Posted by wpoll

All good then. My 2005 was "born" in February and they didn't make the breather change until August. The "loo roll" was utterly buggered when I pulled it...

Yes, I've seen some horrible photos of them....

[wpoll]

Originally Posted by nice1guv

... Glow plugs only affect starting, so nothing in that one.

I'm pretty sure that the glow plugs are used during running, if the cylinder temps drop too much, as least on later cars/engine - but likely not on our older M57/M57N versions - more likely on the variants with a DPF, i.e. E70 with the M57N2 etc.

Keeping the cylinders up to full temps helps with emissions, something BMW worked hard to bring down on the E70 and newer.

[wpoll]

Originally Posted by Salty_Dog

The old style pcv was never in the 2006 model.
But I did change it 4 years ago anyway.

Yes... I'm well used to the X5 normal range behavior in relation to driving conditions....
We have never seen 999 range for a year or more now...

First I thought it was foaming in the diesel when filling up.
But it can't be that this many times in a row

Well, clearly something has changed. As already stated, check the obvious and easy items first; air filter element (did I say easy!?) and then look at the EGR valve on the intake - if this get clogged, it'll kill your performance.

[Salty_Dog]

Yes.... I've had a feeling it could be EGR and/or inlet related.

[andrewwynn]

Originally Posted by chrisfuture8;

@Andrewwynn, is this the thread you're talking about:

Close, the topic is covered there but this is the specific thread:

https://r.tapatalk.com/shareLink?sha...8&share_type=t


Sent from my iPhone using Tapatalk Pro

[andrewwynn]

Originally Posted by Salty_Dog;

We are speaking about a Diesel here

*You* were I clearly was not. Totally missed the "d" in the thread name!

Have you done and actual range and fill measurement to see what your true range is? I'm wondering if the computer is just getting an incorrect reading of remaining fuel from the fuel senders.

Also was there a dramatic change like just one day suddenly 1/4 less range or did it work up to that?

Pull up the hidden menu for liters of gas in the tank/s and see what it says. The value should get pinned to the top for the first 10L or so of consumption before it starts to drop.

I've always wondered how on Earth the computer decides to guess the range since it has no idea how much fuel is so maybe that guessing finally isn't working so well.

A couple things to try:

1) fill up completely and measure the actual range and gallons of fuel. See how it compares to the estimate (you may have done already)
2) fill less than full so the tank gauges actually report the correct amount of fuel, then do your own math on range compared to the computer.

What is your avg fuel consumption reported by the computer and how has that changed from before?

[wpoll]

Salty, you didn't accidentally switch the display from KMs to Miles did you?

[andrewwynn]

Best laugh in a week! Awesome.

Fun story related to the concept:

In a rental car as a passenger, the driver gunned the gas to get onto the freeway. As he turned his head left to check his blind spot, I happened to notice the E/M button in the dash and hit it.

Suddenly the "64" in the middle of the dash read "105" and quickly climbing.

The car had a decent motor and the driver was unfamiliar with the power and was entirely convinced it was that much more powerful than his own rickety car.

Funny coincidence that the ratio is just about that amount.

[Fifty150hs]

One other thing to check which I came across by accident. The transmission cooler thermostat, if you have an automatic. My fuel mileage recently dropped quite noticeably and I couldn't figure out why. Plugs are almost new, air filter gets changed every 10,000 miles, coils are almost new and the thermostat is almost new. I confirmed the thermostat was working by looking at live data coolant temps and they were as they should be.

So, my expansion tank cracked and when I pulled it to replace it the thermostat for the transmission cooler came apart. So, I put a new one in and my fuel mileage has jumped back up to where it was. It may not be the cause, but it's certainly an interesting correlation. Might be worth checking.

[andrewwynn]

A couple thoughts:

1) did you use the hidden menu test 21 to reset your mpg?
2) have you looked at the mpg calibration in test 20?

You need to determine actual vs indicated mpg/range and determine if your computer is reading wrong or the car is actually consuming much more fuel.

I would probably preemptively strike on the reset mpg calculation in test 21 then see if it goes back to normal. It seems test 20 is for calibrating the fuel consumption of it's inaccurate.