W211 E320cdi 7G poor consumption

[gIzzE]

It doesn't matter how it was cleaned 3 months ago, if it is not regenerating it will be blocked again.

You need to find out why it is not doing a regen?

How many miles a month do you do? If you do 1000 it should have done 10 more regens by now, if it hasn't it will be gobbling fuel.


Still not clear on the gearbox issue?
You said...

...I recently had to change the gearbox on my car. Ever since the mpg has been poor.

This was the gearbox on this car?

It was getting good MPG before you changed the gearbox?

If so what was changed? The whole thing? Torque converter?
Definitely a gearbox from another E320cdi pre facelift?
Gearing is correct?

 

[Deleted member 6183]

Combined MPG for these cars is 37.4 and over the last 20,000 miles this is what mine shows.

Have done a few brim-to-brim calcs and the dash is showing a little low, my calcs are nearer 39/40 MPG.

This will be for 80% motorway and fairly heavy footed driving style.

In my view you should measure over longer distances to assess whether all is OK as it's too easy to show very high or low MPG over short sample sizes. Crikey, coming across all LEAN/Six Sigma here!

 

[BlackC55]

How about doing a Terraclean?

 

[jon_viola]

Thanks All.

DPF and catalyst had a chemical clean and furnace burnout 2k miles ago. Car did lots of sitting in London traffic before me so suspect it's rather bunged up. Am now doing more m'way miles in it so hopefully it will loosen up.

I'll try the 2t oil and report back.

New gearbox from Merc incl torque converter and fitted by specialist.

Only had the car a short time so don't know if the gearbox has changed the mpg but it's certainly low.

Will try all of your suggestions over the next few days and report back.

Thanks so much!

 

[jon_viola]

Interestingly the stated tyre pressures are not stated as high....

 

[jon_viola]

 

[automaniaman]

Its a 2005 (55 plate) V6 with full AMG kit including exhaust tips. "Looks like an E55 Estate".

And now appears to be running like one...

 

[gIzzE]

Well it states between 33 and 38 front and 33 and 46psi rears on cold tyres, 4psi more if they are already warm.

I found mine at 33 all round used to average about 33mpg, on 225 wide 17s, so if you're on 245 fronts and 265 rears and 18s I would think about 31mpg would be a bout right.

When I upped the pressures to 36 front and 38 rear my average crept up almost 10% to 36mpg. Any more than that and I lost comfort so didn't try for a prolonged period.
When I upped them to 38 front and 44 rear I was on my way to Ipswich, so reset the OBC and got great results, I even took a picture, however, I found it crashy over ironworks and speedbumps etc. so dropped them back to 36f and 38r.

 

[gIzzE]

Here is the pic...

That was sat at between 45 and 60mph most of the way, so not really pushing on, but still the best I had ever seen by quite some margin.

 

[Deleted member 6183]

Here is the pic...

That was sat at between 45 and 60mph most of the way, so not really pushing on, but still the best I had ever seen by quite some margin.

I always find that my MPG increases when I visit your part of the country from Wales - wonder why?

 

[gIzzE]

I always find that my MPG increases when I visit your part of the country from Wales - wonder why?

You're not slowing down looking for sheep?

 

[gIzzE]

Sorry, couldn't resist.


I always find that my MPG increases when going to teh highlands, so not sure if it being so flat actually makes a difference?

I think it might be because when there I stay of the main roads and trundle round everywhere on slower roads not knowing where I am going.

 

[jon_viola]

Is that ok?

Thanks!

 

[Deleted member 6183]

Sorry, couldn't resist.


I always find that my MPG increases when going to teh highlands, so not sure if it being so flat actually makes a difference?

I think it might be because when there I stay of the main roads and trundle round everywhere on slower roads not knowing where I am going.

On reflection I'd probably put it down to the lack of hills and slower speeds due to less motorways.

 

[davidjpowell]

Don't forget now it's getting colder that at some point anti-thickening chemicals will be added to fuel that will reduce mpg...

 

[gIzzE]

Yeah when do they swap, this is the first tankful in a months where I am not hitting 500 miles in the ML, so think they may have swapped to winter derv this week.

 

[gIzzE]

View attachment 46353

Is that ok?

Thanks!

Yeah that looks ok.

I take it that it gets there in 10mins or so and doesn't fluctuate?

 

[Bellow]

Yamaha Fan who started that discussion runs a 3 litre Mercedes E Class diesel with a DPF, and it was Mercedes that used 2 stroke in their Paris to Bejing run back in 2007 as they were not certain of the fuel quality of the fuels they would be able to get hold of in certain countries.

Presumably they were using it as the lubricity of the fuel obtainable was questionable. That is the only reason you would use 2 stroke oil in a Diesel - added protection for the high pressure fuel pump.

The notion that it acts as a detergent is fanciful at best. Has no one noticed the mess a 2 stroke exhaust gets into? Or the exhaust port solid with carbon solely because of the oils presence?

2-stroke oils are all about wear protection and little else other than avoiding spark plug fouling. All about the quality of the base oil and the anti-wear additives. That is what 2 stroke oil is. And all the other stuff that a 4-stroke oil has to make it last 6k miles+ is left out as unnecessary for an oil that passes through an engine in 7.5 millieseconds even when the engine is turning at a lowly 6000rpm. Its 'detergency' is in the absence of additives a 4-stroke oil would have that create ash when burned. Not in any ability to clean.

Mixed at a ratio of 2.5% of fuel tasked with preventing piston to cylinder siezure, crankshaft lubrication, and cooling, there just isn't the volume of oil to permit detergent additives - it's all oil and anti-wear additives.

Use it for it's superb lubricating properties by all means, but if detergency is sought - use a detergent.

 

[Rory]

Yeah when do they swap, this is the first tankful in a months where I am not hitting 500 miles in the ML, so think they may have swapped to winter derv this week.

It is around about now, but it's also been quite a lot colder this week.

 

[gIzzE]

Presumably they were using it as the lubricity of the fuel obtainable was questionable.

Yeah of course.