[WillLowe]

So I had my car recalled and had the EGR change, I got the car back almost 3 weeks ago. Since then my MPG has dropped from 42 to 35 and seemingly still dropping daily. I'm driving in the same roads I'm similar conditions if anything warmer weather should make the car more efficient I'd think. I was expecting the diesel consumption to drop not increase. Has anyone else noticed this? And should I contact BMW

[HighlandPete]

Originally Posted by WillLowe335d

So I had my car recalled and had the EGR change, I got the car back almost 3 weeks ago. Since then my MPG has dropped from 42 to 35 and seemingly still dropping daily. I'm driving in the same roads I'm similar conditions if anything warmer weather should make the car more efficient I'd think. I was expecting the diesel consumption to drop not increase. Has anyone else noticed this? And should I contact BMW

Could be several factors involved, like running with less EGR before the recall (and getting a higher mpg figure) than present EGR values.

Is the mpg from the OBC, or calculated mpg? If it is only from the OBC, I wonder if any software update has changed the correction factor for the OBC and it is now reading at a different calibration. Has been known to happen, even with unrelated software updates.

I'd be looking to see if you are really using more fuel, before too much dealer involvement, although no issue raising it with your garage. They may ask you to get a calculated figure, see if has really dropped off.

[WillLowe]

Both the indicated mpg and the actually tank to tank I'm having to refill a day earlier than normal so somewhere between 50 - 100 miles less from the tank which is somewhat substantial on my 600 - 800 mile a week commute

[SkyJawa]

If the software was updated then quick likely.... not the first time it’s effected mpg.

[smorg99]

Did anyone get any paperwork stating what work they actually did when in for the recall? I never. I had my brake fluid done at same time so assumed it was on there but didn't notice until I was back home. Couldn't be arsed to go back and ask. EGR was replaced but would have been nice to have known if software was updated etc.

[Terryk]

just received a letter for EGR check and if needed replaced.
I have been reading a lot that after the EGR replacement most of drivers had poor mpg in same road conditions etc.
I would say that a software update should make things better, even in engine's economy with a decrease in fuel consumption instead of an increase...
I have booked an appointment to have the egr checked but I am sceptical for the results.

[northern monkey]

Unsure about mpg loss but I swear my car's running so much hotter. Short or long distance, I get to my destination and the front wings and bonnet are so bloody warm. Been like this since I got the car back on Xmas eve (5000 miles ago).

Anyone else finding this?

[Watsey]

I had a similar experience (reduced mpg), but related to the dealer software updating my car without my permission when it was being serviced.

Around a 4mpg drop, equating to ~50 miles per tank.

My strong hunch is that it was a covert dieselgate adjustment, "a quality enhancement, sir", causing the car to run a lot more EGR. Correcting the emissions by burning more fuel - go figure.

No matter - I had it corrected by coding-out the EGR altogether when the remap was reapplied.

[Becbois]

This exact same thing has happened to my 5 series. Really poor performance but BMW 1 Hindhead refuse to take responsibility for it even though the difference was immediately after the work was carried out!

[Mr Whippy]

Just had mine done.

Hard to gauge the change as I had a 320d courtesy car to drive home and back in.

335Xd felt a bit noisier (could be NVH between G and F series?), and not quite as fast till really on it (could easily be top end throttle on 320d making it feel perky down low but flat up top)

No idea on economy.


Since I’ve been in for two EGR recalls I can’t imagine anything too nefarious as they’d have made the biggest changes previously?


The good BMW tuners should know what’s what because they’ll see the maps before/after and know what’s changing.

I highly suspect it’s EGR calibrations for the operation of the cooler and EGR itself, but they react to driver torque demand (throttle)
At full throttle no EGR will be requested as it’s not needed.

All EGR is really doing is throttling out excess oxygen by using exhaust gas.

I can’t imagine there is too much there in calibrations to make a car that much cleaner on NOx vs economy.
EGR is there to tidy up NOx, economy was tuned for type approval and CO2 ratings.
I don’t know enough about it, but I can’t imagine BMW could have calibrated NOx and CO2 to ‘cheat’ anything that’d be noticeable to normal use.

From what I gather the VW cheat stuff was a specific software device to detect the mpg test and run a specific software to give crazy mpg while giving poor NOx?!

[TurboWeasel]

I thought exactly the same thing when I had a 2021 420d on loan whilst my F30 330d was in for service, but it's just the B47/B57 in the G series is noticeably smoother and quieter than the N47/N57. Better noise insulation and engine mounts in the Gs as well.

The B47 is also punchier low down than the N57 30/35d in any case, it's just a turbo sizing thing. As you say though, no where near the same clout from 3000rpm upwards as the 30/35d though!

My 30d's recall was done 11 months ago, just prior to my ownership, so I don't know if it's performing as it should but I've done 14K miles in it since and the long term average over that distance is currently sitting at 49.8mpg. Seems reasonable to me, so I have no reason to suspect the recall buggered something up. I wish it was punchier low down though as it feels pretty lethargic in comfort mode below 2500 rpm, unless that is the issue folk are complaining about?

I can hear a lot of boost control chuffing and whooshing on medium throttle, so maybe the boost maps were altered as part of the recall? Hmmmm. Or if they are simply opening the EGR valve more often as part of a stealthy "dieselgate" retrospective fix as already mentioned, which could also impact performance, in theory. Dumping soot into fresh intake charge is never going to be good for performance. It 'should' only switch on under light load conditions.

Yeah the VW's detected the rear wheels not spinning, therefore altered the map. It was when in 'normal' mode their emissions were way off the quoted numbers.

[Kermit]

Just returned from having the EGR cooler recall done and happily none of the software has been touched, including the remap, which is still large as life. Apparently all that needed to be done was to tell the car the new part number...? Very happy that I don't need to treck to Luton to have the map put back on!