Poor mpg for c270 diesel?

[psmart]

psmart, thats interesting. If there is a problem with the MAF, is that something that you will find out if you connect the car to a computer. Don't want to spend for new MAF if it dosen't do anything...

I have new air filter in mine so it will be the MAF, Injectors (hope not as it is really expensive), intercooler or choked up exhaust ( How do I find out?)

It should show me better MPG than 35 to 41 as 41 as max for long range, highway driving on 56 - 60 mph all the time.

Unfortunately not, I found a lot out about the MAF characteristics plugged into CarSoft whilst driving to diagnose a gearbox problem through trial and error (as CarSoft showed no useable data regarding the MAF). I had the MAF disconnected and the fuel consumption rose, power was down, albeit Torque was similar, which I found interesting as I would have assumed that no MAF would mean lower torque to protect the gearbox.

When I changed the MAF on the ML there was a difference, especially as I drive at high speeds over 260miles each weekend, I noticed the tank not dropping as quickly (no computer in the ML, you had to use tank-tank checking). On another fault, I drove with the Turbo disabled and got just short of 40mpg (~39mpg) over 800miles driving around 50-60.

After changing the Turbo and cleaned out the intercooler and all associated pipes a lot of gunge came out of the intercooler (the engine crankcase breather vents into the air stream before the intercooler), difficult to know if the gunge was lodged in a place preventing air-air cooling, but sounds logical.

 

[The Pan Man]

Since Service

Since Monday I have done 250 or so miles all traffic work shopping visit to mothers trip to golf club type of journeys, since reset the figure is now 39.8 mpg. My driving style has been described as "Progressive making good use of presented opportunities" Read "He dont hang about" I would expect this figure to rise to over 40mpg as it was covering the previous x000's of miles.

I will put this comment in and you can all analize your situations.

If I leave home and turn right I'm immediatley in traffic, Roundabout within 200 yards 2 traffic lights 4 pedestrian crossings, however if I start my journey by turning left my first stop or not is 7 miles away. These two types of journey greatly affect the shown current mpg first one is in the high teens whilst the other will show 30 mpg within a couple of miles including a half mile straight climb with overtaking oportunities.

 

[GCLTuning]

tony2311 - If you havn't already...It would be a good idea to run a diagnostic test through the car just to make sure there are no problems. In our experience with economy on the 270 CDI engines that does seem very low compared to what it should be. We did some work on the C270 engine a few days ago, it was averaging 40 MPG as standard.
The MAF could be causing a problem, we very often come across faulty MAF's that are reducing performance and economy. If you unplug it, it will go into a pre-set mode, if the car improves with it unplugged then this could be your problem.

Kind Regards,

GCL

 

[maggragg]

I was coming from a trip to Reykjavik and after 150 miles, there of 120 miles on highway at 56-60 mph and 30 miles in Reykjavik, still avarge speed 50 mph the car shows 36 MPG that I find to low.

I just unplugged the MAF and found no diffrence other than the car was maybe little more powerful but it´s hard to tell.

So it must be the MAF that is faulty...

 

[psmart]

My MAF wasnt faulty per-se, when I changed the Turbo I cleaned the MAF out (I think its Parrot of Doom who has an article doing this), but 35K later when the gearbox went faulty and I was fault finding, I changed the MAF and there was a noticeable difference in response, acceleration and top speed from the old MAF and a big difference between no MAF and the new MAF.

The engine has multiple sensors, such as the boost pressure sensor and temperature sensor, but the MAF is needed to know the density of the air, its incoming temperature etc to evaluate the correct combustion charge. People only really tend to know there is a MAF problem when the engine ECU detects something out of kinter and goes into emergency mode, it strikes me as being wierd why they dont have it as a serviceable item.

I bought the MAF complete from Merc, but there are a number of threads where people by the Bosch internals for far less money, would be worth doing a search, or perhaps cleaning your MAF first (see the DIY section).

 

[maggragg]

I will try to clean it first otherwise I´ll buy new one. I found out that the car seems to have a little better MPG without the MAF connected so at the moment the next thing is to see what changing the MAF will do with the MPG and hope to get it down to where it should be.

 

[maggragg]

I was looking at the MAF and just aside of it is another sensor with part nr "A 004 143 32 28". What is that sensor as I can't find it online. Also what is normal temerature for the cooling water. It seldom rises to or abowe 80 degrees celsius and normally is one notch under it. Is that normal? Also is there an easy way to accses and clean the intercooler?

 

[Mounis]

E220cdi (W210), Manual - 58 mpg, E220cdi (W211) - 49mpg

I have two E220's, both are used on the fleet, daily drivers, both running 200k miles and both return averages of 39mpg ish in town (London) and the max as stated above...

I have noticed that they tend not to be anywhere as good when needing a service...

Having said that when I service them I do change everything - all filters, Mobil 1 oil, use injector cleaner and I tend to strip all the hoses up front and wash and clean them before refit...

Perhaps its placebo effect here... but they both def seem to have plenty of power and torque... I'm also a firm believer of not nursing engines too much so on the mway they do get given some stick...good to clean them out...

Also I tend to change where I'm buying fuel from on a tank to tank basis... The way I see it, if its good to change your shampoo and toothpaste then it's gotta be the same for the girls... ;-)

 

[tony2311]

tony2311 - If you havn't already...It would be a good idea to run a diagnostic test through the car just to make sure there are no problems. In our experience with economy on the 270 CDI engines that does seem very low compared to what it should be. We did some work on the C270 engine a few days ago, it was averaging 40 MPG as standard.
The MAF could be causing a problem, we very often come across faulty MAF's that are reducing performance and economy. If you unplug it, it will go into a pre-set mode, if the car improves with it unplugged then this could be your problem.

Kind Regards,

GCL

i unplug the MAF and the car runs sluggish but the mpg gone up by 5mpg, Does this point to a new MAF? saw a pierburg maf on ebay for £68 is that any good?
my last tankful , i got 350miles from it average 30mpg which i think is not good for diesel

 

[maggragg]

http://www.maf-shop.com/product_info.php/info/p64_BOSCH-Luftmassenmesser-Mercedes-Benz-0281002535--6460940048.html/XTCsid/8c72d1d8f1aeb84f7ba24ec22752ee96 I found this unit that has two sensors in it and comes only complete. What is the other sensor and should I replace the whole unit or try to buy only the MAF sensor from Pierburg? This is really expensive here in Iceland

 

[psmart]

I found this unit that has two sensors in it and comes only complete. What is the other sensor and should I replace the whole unit or try to buy only the MAF sensor from Pierburg? This is really expensive here in Iceland

Article on the MAF :- http://forums.mercedesclub.org.uk/showthread.php?t=25775

Basically, the unit has a temperature sensor and from what Ive seen, its a wheatstone bridge with one element heated. Basically, 5 connectors from memory.

 

[anisamy1]

got a 02 c270cdi. had a secondhand engine in recently, i am averaging 30mpg at average speed of 29mph. my journey is mainly 24miles of motorway/aroad twice a day (school run) and i drive to work 2 miles most days small roads but no jams. i get 50mpg on the same journeys on a scenic.
i know c class are heavry and its auto but 30mph average doesnt look good. is this about right or is there something wrong with my car?
i see others on here get regular mid 40s so it looks a big difference

Check it again after changing the engine oil.

 

[tony2311]

I have just Brought a new MAF from local mercedes dealer in sheffield, The cost with 10% discount was under £54. Just going to see if it improve things before i get the car to a specialist.
If you are after a new MAF for diesel. your dealer might be cheaper

 

[maggragg]

Tony.

Does it look like this one with the two sensors in it http://www.maf-shop.com/product_info.php/info/p64_BOSCH-Luftmassenmesser-Mercedes-Benz-0281002535--6460940048.html
This one is the I can buy but they tell me that Bosch only sells the unit complet. They at www.Maf-shop.com tell me that Pierburg wont work in this unit.

 

[tony2311]

on my car it has only one sensor on that bit, Was told diesel sensors are much cheaper then petrol.

 

[The Pan Man]

Deliberate experiment yesterday

Yesterday Morning I had to go to Beeston just outside of Nottingham the journey was about 70 mile in total with 45 Motorway and 25 A & B roads departed aprox 09.00 hrs.

I sat at the posted limits all the way until there was a shunt just south of J25 M1 Northbound and up unil that point I had averaged 58MPH at 53 MPG. Obviously as I sat in the jam the averages all started to fall, I reckon with a bit of luck I would have got 59 MPH and possibly 55MPG. Not too shabby for a 270 CDi with 94,000 on the clock.