XSeries-forum

Needs a longer run to do a regen that is why your oil is looking like it is going up but it is diesel in it from failed regen's
I used to go down the duel carriageway with the wifes Leon once a month in sport mode and cruise turned on when it got to about 3k revs only 18/20 miles but it did the trick kept the dpf happy.

I have checked the temp when getting back in from a 7.6 mile dive and the temp in the hidden menu said 93c.

Also i have checked my diagnostic again defo says that the last regen was completed fine but doesn't tell me about any pervious regens so couldn't say if they completed fine or not.

Doesn't sound like the stats are the problem then on this one and good its done a regen .

So fitted the new turbo to intercooler pipe and ive done another mpg calculation and its at 26.37 so still not where it was before the issue started and that strange noise seams so be getting slightly louder so i got a day off tomorrow. Going to get it jacked up and get the stethoscope out and have a listen around to see if i can pinpoint it.

Another update for everyone ive looked everywhere and just cant find anything obvious. I did find a few things that are concerning.

1. There seams to be a patch of black soot on the exhaust flex pipe that comes of the DPF so possibly a hole inside as the out side of the flex piece doesn't have a obvious hole in it.

2. While i was underneath i noticed it had a fuel filter on it that was a unknown brand so changed it to a BMW one and when draining the old filter there was a very small amount of metal partials in the fuel out of the filter. I used a magnet to collect the metal from the drained fuel and was in total about 5mm square patch of particles.

So maybe the hole in the flex piece could be causing the reduced MPG and the strange noise but don't know if it would have that much of a effect as its after the dpf and all the sensors. The big down side to this is that as far as i know the flex piece is welded onto the dpf and is not a replaceable part except for a whole new dpf.

Metal particles in the fuel is bad news there shouldn't be any possibly the in tank pump is on the way out but if any has got further than the filter it will cause major damage to injectors and main pump.
I'm sure you could get a new flexi welded on of needed instead og a whole new dpf we got one welded on our focus cat last month when it snapped.

The flexi-device (called a ‘decoupling unit’) is very definitely available separately (but possibly not from BMW themselves). Anywhere from £25 to £75 depending upon quality of replacement and whether or not there’s a bit longer pipe on each end. I’d be surprised if it caused that big a drop in mpg though.

We are on winter diesel now (which has some effect) and it takes longer for diesels to go from ‘cold’ to ‘warm’ as far as the DDE is concerned (which also has some effect). Other things are worn injectors allowing more fuel through, dirty MAF causing incorrect air/fuel mixture data into the DDE, possibly a bad O2 sensor giving bad data to the DDE. Even a bad (cheap & nasty) or blocked air filter.

Checking fuel flow needs a dynamic test system that can read the injector numbers and would show one being ‘high’ compared to others. Again it’s a big difference and for that ‘bad’ an injector I would expect smoke (even with a DPF). Are the tailpipes clean?

You definitely shouldn’t see metal in the fuel filter (inlet side I hope?) but it may be debris from the filter itself (poor manufacture) as well as something upstream.

Ive been to my local dealer today and yes i can get the the flex part for £116 but needs to be welded on. I have found a kit on ebay that doesn't need welding just waiting on a reply to confirm fitment. https://www.ebay.co.uk/itm/124341525363 ... %7Ciid%3A1

Clean tailpipe and no smoke under light or heavy acceleration.

Yeh the metal partials where in the inlet side of the filter it could be from the old in tank pump that failed a few weeks ago but i arnt ruling out the hpfp or a poor quality fuel filter.

Will also get the diagnostic on it tomorrow and check the o2 sensor number to make sure they are reacting as they should from the live data.

Get ready all this is going to be a long one.

The o2 sensors are reacting correctly on idle and under acceleration according to the live data.

I have finally got the flex replaced the one i linked before was the wrong one but i finally found the correct part https://www.ebay.co.uk/itm/353820141046 ... SwuIxhwHcp fitted it today and there was a small hole in the flex.

While i was under the car with it running to set the exhaust paste i could hear the noise i have been hunting for and after a good look around i think i have found it. In the gearbox / transition bell housing there is a rectangle hole and with a torch i could see the torque converter spinning. Putting my ear close to the hole and finally i think ive found the noise.

I've had a look around and a bit of googling and found out that there should be a cover that acts like a sound deadening plug but its listed as a vacuum cap. So back down BMW tomorrow to get one ordered. (Item 5)

I'm slightly concerned that the torque converted looked covered in rust but going to ask at BMW when i order the part if this is something to be concerned about.

Now for the mpg the latest calculation is at 28.53 its still short of the 31.12 that i use to get but from what ive found online and what some of you have said i am starting to think it is normal. As a rough in the head calculation its about a 9 ish % drop and considering its cold with winter diesel it could be about right. Ive always had petrol cars and never really noticed a winter drop in mpg but maybe diesels are more effected you all might know more about that than i do.

A rusty TC isn’t anything to worry about as all the clever stuff goes on inside it. If it’s just the cover then that’s a simple and hopefully cheap result. Winter diesel does make a difference. My X6 is a little down at present (2-3mpg) and was noticeable on a run to Wales at Xmas (300 miles each way). As suggested, a Diesel engine takes much longer to warm up than its petrol brethren so will stay in ‘cold’ mode for longer too.

I wonder why the cover fell off? Just one of those things I suppose, or knocked during a service maybe and kept quiet!

FWIW Last weekend I did a 300+ mile door-to-door run, during which the outside temp. varied between -1 and +3 deg c. It's a run I've done many times, but rarely in winter. I would usually expect to get somewhere around 40mpg, but this time it was only 35. As mentioned, winter has that effect on diesels.

Coincidently, the best fuel consumption I ever got with this car was on virtually the same run with an ambient temp. of c.30 deg c. and that was 44mpg.

X5Sport wrote: ↑Fri Jan 21, 2022 10:39 pm I wonder why the cover fell off? Just one of those things I suppose, or knocked during a service maybe and kept quiet!

Well when this noise started it went back to the people i bought it from to investigate a judder it had in the mornings just before the warranty ran out and the next day i picked it back up it had this noise so i am thinking the same that they removed the cover to check the converter and just not put it back on or maybe they broke it when removing or just couldn't be arsed to put it back on.

Either way i wont be buying a car from them again.

(Thought i would mention they said there was no judder but it turned out to be a failing in tank fuel pump)

StyBeeDoo thanks for the figures from yours i am thinking the mpg drop is just a normal winter thing for these cars. The problem ive been having is that i have been trying to link both the problems together ie low mpg and a new noise when they might actually be separate things. If that makes sense.

And that's the reason its been a pain to get it sorted because ive been chasing a symptom that might not actually be a symptom.

Got the part today was 5 mins to install but still no luck the noise is still there.

UPDATE

The noise is still there and now it seams to have started whining when accelerating but quietens down when you hear the turbo spool up.

Had to pick my brother up yesterday from Manchester so a 105 mile round trip and the fuel just disappeared the car said it was doing 51 MPG but filled back up and calculated and it actually did 38.92 that was at 70 with the cruise on and light traffic all the way and back. So with that big of a discrepancy with the numbers there has got to be something big going on.

Also it seamed to have no power at the top end it would go from 0-40 fine but anything after it just seams like its bogging down and don't even try to overtake as with the foot to the floor it just sits there.
And about 5 miles from home it did a strange judder as if you where pressing and releasing the brakes for a few seconds and then stopped.

Still no codes at all, i have just hit a dead end and not sure where to go from here.