07, E70 3.0D MPG issue - Trouble shooting

[Twisty]

Hi All,

So I bought an 07 E70 3.0D a few weeks back. I have done some long drives, 4-5hr motorway cruises, usually a steady 65pmg.
When I first got the car, I reset the mpg readings etc, and after a long journey was getting about 31mpg, after a week of driving short distances to work it was about 30.2mpg. Another long journey through the welsh valleys, up hils, stop start etc it was still 30.2mpg - pretty happy with that.

As I was checking things were all ok - codes etc. I noticed the temp never got over 70C. Off I go and change the engine oil and filter, air filter and both thermostats. Car now runs at correct temp 90C or so. But now, the car has dropped MPG! I just did a long drive 65mph taking easy, and I was getting 25mpg, doing some short distances to work its around 27mpg now.

Have I done something when changing the thermostats to cause this? Items I removed was just the air intake, EGR cooler and turbo pipe. Obviously all back on now...

I should add, when I got the car, glow plugs 1 and 2 were showing codes 4212 and 4222.
Now I have a code for DPF - 425A - I am not sure if this is related in anyway, or has only just come up since changing the thermostats.
No other codes.

Should I just accept the sudden reduction in mpg or can I start troubleshooting by looking at parameters via protool?

[X5Sport]

I assume you mean a steady speed of 65mph?

If you have glowplug errors then the DPF will not regenerate as the system uses all 6 plus extra fuel to burn the soot off. You’ll need to replace them (probably best to do all 6) as well as the controller unit. Do not mix manufacturers, especially Bosch plugs with a BERU controller. They use different voltages! Members have changed plugs and not the controller only to have the controller itself fail shortly after.

Before you try to remove the glowplugs I really recommend spraying some form if anti-seize fluid onto them for a couple of days. They are known to snap easily. BMW also recommend doing so in the Service Manual. If one does snap then there are toolkits for extracting the bits, but best avoid that scenario if you can.

Once changed, the car should regenerate and that should clear the DPF error. You should do a good run at above 40mph for at least 20 minutes once fully warmed up. As you have the error, it might take a little longer to complete.

You mpg issue might be related as the car is now warming up but the exhaust is partially blocked.

[Leslie]

Is it code 452A not 425A ? which is dpf predicted life end , , a warning appears on the dash soon after startup.for a few secs. .It usually appears around 160k and doesn't cause any issues apart from being annoying.

[Twisty]

I assume you mean a steady speed of 65mph?

If you have glowplug errors then the DPF will not regenerate as the system uses all 6 plus extra fuel to burn the soot off. You’ll need to replace them (probably best to do all 6) as well as the controller unit. Do not mix manufacturers, especially Bosch plugs with a BERU controller. They use different voltages! Members have changed plugs and not the controller only to have the controller itself fail shortly after.

Before you try to remove the glowplugs I really recommend spraying some form if anti-seize fluid onto them for a couple of days. They are known to snap easily. BMW also recommend doing so in the Service Manual. If one does snap then there are toolkits for extracting the bits, but best avoid that scenario if you can.

Once changed, the car should regenerate and that should clear the DPF error. You should do a good run at above 40mph for at least 20 minutes once fully warmed up. As you have the error, it might take a little longer to complete.

You mpg issue might be related as the car is now warming up but the exhaust is partially blocked.

Ha yeah I meant 65mph!
I thought the DPF can run on 4 plugs working on 6 cylinder cars? Not sure how true that is to be fair.
Thanks for the heads up on the matching brands of glow plugs and module. Sounds a bit sketchy taking them out.. I’d be devastated if one snapped.
DPF is showing about 40g of soot and ash, so hopefully it’s not blocked.
The code is for end of life mileage readings too, so hopefully still good for a while

[Twisty]

Is it code 452A not 425A ? which is dpf predicted life end , , a warning appears on the dash soon after startup.for a few secs. .It usually appears around 160k and doesn't cause any issues apart from being annoying.

Yes you’re correct, I put it wrong - it’s for the end of life readings so just a number it reaches before it triggers. Hopefully it’s all good

[Leslie]

For what it's worth I don't have a single working heater plug now and my 2009 sd regens just fine. .The thermostats are important though so good you have changed those.I think it's too risky to try removing my heather plugs now when they are not causing any issues , they are possibly more an issue on newer models but ours can run fine without.I get 29 mpg average and 34 on a gentle 20 miles but once you go over 55 mph you can watch the mpg drop back.
I got the dpf life counter reset and that took care of the warning and it's still working as the exhaust pipes are clean.

[Twisty]

For what it's worth I don't have a single working heater plug now and my 2009 sd regens just fine. .The thermostats are important though so good you have changed those.I think it's too risky to try removing my heather plugs now when they are not causing any issues , they are possibly more an issue on newer models but ours can run fine without.I get 29 mpg average and 34 on a gentle 20 miles but once you go over 55 mph you can watch the mpg drop back.
I got the dpf life counter reset and that took care of the warning and it's still working as the exhaust pipes are clean.

Good to know about the glow plugs, thanks.
I had a 1 hr motorway drive today, before the drive soot and ash were about 40g. After the drive soot was about 3g, ash the same, so I am guessing it’s doing its thing all ok!
I just can’t work out what I’ve don’t to lose about 4mpg. Not the end of the world as it seems to be running well! Just frustrating.

[Leslie]

Its soot thats regeened, ash is there forever and slowly builds till its full .

[X5Sport]

Perhaps it’s the N57 (2010 onwards) engine that won’t. My X6 wasn’t until it got new plugs a few years back. Could be it’s another reason to stick with the older M57 engine!

[Twisty]

So, I found this was happening on the battery, the negative terminal was completely corroded stuck. Lots of bicarb paste later and it was dissolved off, cleaned up and put right. However the black plastic casing thing had completely melted - probably get one of those soon...

The car had no warnings related to battery or strange dash lights or anything, was starting fine that was until yesterday when I was cleaning it out for a few hours and then the battery went dead, which led me to look check it out.

Protool told me the car thought the battery was a 90ah AGM battery, not a 100ah lead. changed the battery type using the app.
strangely the codes for glow plugs 1 and 2 have now gone!? Coincidence?
Would the mess of corrosion be down to the car thinking it was an AGM not lead?

[X5Sport]

I haven’t seen a car battery in that state since the 1970s. Unlikely the setting had any effect as all that changes is the charging voltage and charging cycle monitoring by the Intelligent Battery System. A battery connection in that state implies a leak either with that or a previous battery. If the ‘fur’ wasn’t cleaned properly then you got what you have on your old one. It would probably have caused earthing troubles and that could well have thrown a code. Glowplugs are very low resistance to deck. A bad (high resistance) earth connection on the battery would have made the controller think there was an issue.

BMWs are fitted with AGM batteries by default and have been since the early 2000s. I don’t know what Protool are looking at for reference, but that isn’t what BMW put in.

90Ah AGM was the standard with an 019 format. In 2019 those were replaced by a 92Ah AGM as the 90Ah OEM stopped production.

Make sure the venting line is connected. There’s a pipe connected to one end of the battery to vent charging gases (mainly hydrogen) overboard. You can just see it at the bottom of your image (grey pipe).

[Leslie]

Wow that is nasty surprised it's been still running , when I did look at mine recently I found quite a bit of white oxidation but nothing like that, is there any water getting in although its that spare wheel has been put in there damp might have caused it .There are apparently some earth's on the floor, was mentioned by someone on here so worth a check too.Given the cost of Agm batteries most older x5s now are running a lead acid battery. Mine has been for at least 8 years .

[Twisty]

I haven’t seen a car battery in that state since the 1970s. Unlikely the setting had any effect as all that changes is the charging voltage and charging cycle monitoring by the Intelligent Battery System. A battery connection in that state implies a leak either with that or a previous battery. If the ‘fur’ wasn’t cleaned properly then you got what you have on your old one. It would probably have caused earthing troubles and that could well have thrown a code. Glowplugs are very low resistance to deck. A bad (high resistance) earth connection on the battery would have made the controller think there was an issue.

BMWs are fitted with AGM batteries by default and have been since the early 2000s. I don’t know what Protool are looking at for reference, but that isn’t what BMW put in.

90Ah AGM was the standard with an 019 format. In 2019 those were replaced by a 92Ah AGM as the 90Ah OEM stopped production.

Make sure the venting line is connected. There’s a pipe connected to one end of the battery to vent charging gases (mainly hydrogen) overboard. You can just see it at the bottom of your image (grey pipe).

The vent line is connected. And your probably right about coming from the old battery. Car is new to me, a month or so, looking thorugh receipts, there is a 2018 garage service which has a comment about corrosion on battery terminal, also in 2018 a new battery was purchased (the one that's in there now). I imagine previous owner replaced the AGM battery with the lead and never got the car coded.

[Twisty]

Wow that is nasty surprised it's been still running , when I did look at mine recently I found quite a bit of white oxidation but nothing like that, is there any water getting in although its that spare wheel has been put in there damp might have caused it .There are apparently some earth's on the floor, was mentioned by someone on here so worth a check too.Given the cost of Agm batteries most older x5s now are running a lead acid battery. Mine has been for at least 8 years .

Looking through receipts, this lead battery has been installed, most likely with corrosion on the clamp from previous battery and was never coded correctly. that was back in 2018, its done well for nearly 7 years with the wrong type of battery installed and not even coded!

[Leslie]

It clearly wasn't an issue either to last 7 years which is a very decent battery life