High fuel consumption w212 e350 cdi estate

[b21playa]

Hi all

Started to notice excessive fuel consumption on my car recently, it’s getting bad. A full tank will only do 400miles mixed driving.

I took the car out yesterday for a 60mile drive in the motorway with a steady speed of 60-70mph, no traffic and cluster should 39.8mpg. Thermostat was changed last year and car gets to temp fine and stays there. My mpg over last 5000 miles is 26, which is bad for a diesel.

Any ideas or advise welcomed

 

[DSM10000]

Have you measured it with a brim to brim tank calculation?

You say "mixed driving"

Diesels are not good in slow or city driving so this can impact on overall economy, also the cooler temperatures we are experiencing will mean the engine takes longer to reach full operating temperature. It can also affect tyre pressure, have you checked yours are all correct?

In addition, most filling stations have moved to winter diesel fuel which can also have an effect on economy.

 

[philnewmerc]

Short runs in a diesel will produce very poor MPG. Petrols get up to temperature quicker so can be better for short trips in town. However once a diesel is up to temperature it's actually quite good around town, hence all the professional drivers used to use diesels. The MPG your cluster showed on the motorway sounds good (even if it's more like 35, still fairly typical for a very big diesel car with a big engine). So maybe you just do lots of short runs that lower the average?

 

[b21playa]

Have you measured it with a brim to brim tank calculation?

You say "mixed driving"

Diesels are not good in slow or city driving so this can impact on overall economy, also the cooler temperatures we are experiencing will mean the engine takes longer to reach full operating temperature. It can also affect tyre pressure, have you checked yours are all correct?

In addition, most filling stations have moved to winter diesel fuel which can also have an effect on economy.

Hi

Yes brim to brim calculation. Mixed driving meaning 50/50 split between local and then motorway driving. Yes winter mpg has always dropped

This is been happening for a while to be honest, over summer as well, just haven’t got around to looking into it as I brought another car and been using that more.

I’ll check tyre pressures thanks

 

[b21playa]

Short runs in a diesel will produce very poor MPG. Petrols get up to temperature quicker so can be better for short trips in town. However once a diesel is up to temperature it's actually quite good around town, hence all the professional drivers used to use diesels. The MPG your cluster showed on the motorway sounds good (even if it's more like 35, still fairly typical for a very big diesel car with a big engine). So maybe you just do lots of short runs that lower the average?

Quite possibly doing lots of shorter journeys and not realising. I’ll have to remember my journeys, can be 6-7weeks before I brim it again as it’s not used as much.

 

[b21playa]

Just checked and tyre pressures were a bit low and scanned for codes and had “13AE00 the heater for the crankcase ventilation system has a fault in the output stage”

 

[toteimerced]

Has it been serviced properly, new air filters, oil filter, fuel filter, I personally wouldn’t push oil changes more than 5k, recommend oil changes by manufacturers is ridiculous, oil will break down long before then, transmission service will improve fuel consumption, believe it or not, sport mode is generally better for fuel consumption, if driven normally (check YouTube for videos on that subject), another usually forgotten maintenance, is differential oil change, also, make sure none of the brakes are dragging, if one wheel is hotter, that could point to sticking brakes.

 

[b21playa]

Has it been serviced properly, new air filters, oil filter, fuel filter, I personally wouldn’t push oil changes more than 5k, recommend oil changes by manufacturers is ridiculous, oil will break down long before then, transmission service will improve fuel consumption, believe it or not, sport mode is generally better for fuel consumption, if driven normally (check YouTube for videos on that subject), another usually forgotten maintenance, is differential oil change, also, make sure none of the brakes are dragging, if one wheel is hotter, that could point to sticking brakes.

Serviced every year, regardless of mileage…but this is usually every 4-5000 miles. Last change was oil & oil filter, previous year was same plus fuel filter, air filter, pollen filter.

I’m planning transmission service, have got the parts just waiting for garage to open in new year to change. I checked the wheels after driving and both were fine, I’ll be changing front pads soon so will clean & grease everything up

Is there a way to put in sport and for the car to remember the setting?

 

[toteimerced]

No, just make a point of pressing the sport button when you start the car, myself, I press eco, to turn of start stop, sport and sport settings on the suspension, as part of the startup procedure, which now becomes natural for me.

 

[ALFAitalia]

Which horsepower versions is your 350 CDI?.. and what do you usually get?
I'd be more than happy with near 40mpg! Mine is the saloon in the 231hp flavour.

 

[Gazwould]

I don't understand these diesel slow short run mpg issues

 

[mersum1es]

see it is not regenrating DPF too frequently... Or injectors are good.

 

[b21playa]

Which horsepower versions is your 350 CDI?.. and what do you usually get?
I'd be more than happy with near 40mpg! Mine is the saloon in the 231hp flavour.

I’m not 100% sure, it’s a 2010.

I’d expect more than 40mpg just sat on the motorway for 60miles. Average over tank on brim to brim calculation is 26mpg.

 

[b21playa]

see it is not regenrating DPF too frequently... Or injectors are good.

Thanks. How can I check too frequent regents and injectors?

 

[b21playa]

Just had a Quick Look at the car and looks like the o-ring for the metal boost hose (green I think) is deformed, the Y intake has a crack at the join to the turbo as well as the orange seal not looking so good. I will order new parts for this.

I also checked dpf values but not sure if they are within spec or too high, picture attached for those that may know more

Thanks

 

[b21playa]

this is the mess the boost leak has created

 

[geoffus]

I’m no expert by those DPF levels seem very high, that is if mine are accurate.

 

[mersum1es]

never understood grams in DPF filling, SDS shows percentage too.
Somewhere saw screenshot where 14g was limit in xentry. They are all calculated values, only pressures are real,

 

[b21playa]

Thanks. I have ordered some dpf cleaner which I’ll do once I’ve changed seals etc

 

[MrGreedy]

Ash content (which should be a small fraction of the ash content) is enormous.

Also, 82,000km since last regen!?
These cars regen every circa 400 miles/600km on my experience, or at least my 2011 w212 does.

My guess would be either you've had the DPF mapped out (and possibly gutted), or you bought this car used and the previous owner did this.

I hope I'm proved wrong.
With those wonky readings, I'd personally be getting this to a Merc or remapping specialist with a rolling road who can make sense of the data being presented.