2002 W203 220CDI Fuel consumption problem

[dchantry]

Hi guys,

Still having a few issues with my car
I had poor acceleration problems which were discussed in a previous thread that ended up going to the stealership for new injectors which made my pocket considerably (£1200) lighter.
Dealers told me that the car had also been in a bump.
Since the injectors were changed the car runs a lot better, but the fuel consumption figures seem to be quite poor.
I'm getting about 40MPG from the car and 75% of my driving is motorway and I do drive more like miss daisy than Jenson Button.
I think I'm getting about 30 around town and 45 on the motorway.
I reset the computer on motorway today and then drove home at an average speed of 60MPH. Fuel consumption figures were 47. I went in a similar car last week and they had 58 doing the same.
Last week I tried filling up, driving until the tank was almost empty and then filling up again and I worked out about 39mpg. This is the same as my father in laws 2007 E220CDI
To a tank I'm lucky to get 500 miles.
Any ideas out there what figures I should be getting and if there is anything obvious to check before I go back and pay another £100 per hour at the stealership

 

[dchantry]

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[Mark A]

I'm getting similar fuel consumption figures out of my C220. On an 86 mile round trip I average about 41mpg. When I bought it, I had a good look at claimed fuel consumption figures, and I'm not a million miles away from that.

Mark

 

[alec2]

I have a 2002 auto 220cdi estate and have averaged 41.6 over 44k miles of mixed driving.

On the motorway I seem to do better at about 47.

On a good day of non motorway driving on a long distance trip I can just about get 50!

Around town it is much worse.

If it is hot and the aircon is on then the mpg is lower.

This is based on the car's mpg indicator. But I know from my GPS that the speedo reads 3% fast

Alec

 

[alec2]

Also remember that the 2007 E class has a different more efficient and more powerful engine.

Alec

 

[W203-C220]

If you were used to excellent MPG when you had a couple of duff injectors then maybe they were saving you fuel by metering less?

I found driving my own 2001 C220 CDI without the turbo assistance for about 4 months would achieve up to 60 MPG motorway, seldom less than 50 on a 15 mile trip unless crawling through town.
With the MAF replaced my car revs higher in most gears than before so unless I make an effort to keep revs low it obviously uses more fuel.

Also noticed (now it's keen to rev) it can get too fond of 4th gear and a quick tap to the right will often force an upchange thereby saving you revs & fuel.

My 'overall 'average was 47.7 mpg after 4 months non-turbo use. A month later it's under 45 mpg and drops drastically if the wife drives it! We still get over 50 mpg on motorways with no effort though.

I agree the speedo (and probably the computer figures) are optimistic too. SatNav confirms a 3mph error at 35-40 rising to about 7 mph at 80+ and I seldom get much more than 550 miles from a full tank in general use. The previous owner got 700 miles from one fill, constant motorway use and no turbo though!

Yours sounds a fairly acceptable to me, habitual use of the cruise control helps a great deal I've found, even at 40 mph it seems to save fuel by dropping revs on downhill sections. It all adds up ;-)

 

[W203-C220]

Just occurred to me... you said it's previously been in a prang? And you have a lopsided rear spring problem too? Look at getting a 4 wheel alignment check, especially if you see any odd or uneven wear on any tyres. This is so easily overlooked but poor wheel alignment will increase drag and waste fuel. You may not be able to feel anything wrong, but consider getting it checked. NOT at £100 per hour though... GASP!

I changed my glow plugs recently, had a look at the injectors in case of weeping seals while the covers were off. Heard it's common for the seal/washer where they clamp into the head to starp weeping. Mine were fine and I recall thinking I could probably replace all 4 injector seals in about an hour. £1200 sounds like the injectors were mega-money? How much each?

Kevin
2001 C220 CDI Classic

 

[BlackC55]

Ask the dealer if the injectors were coded properly as the injection quantity is important to be coded into the engine control unit when replaced,

 

[dchantry]

Thanks for help guys.
Injectors were £178.56 each + Accessories. 2 were faulty but they recommended changing all 4 (which someone independant actually backed up).

I asked about coding the injectors and their response was of course we did, (spoken in a who do you think we are voice)

Have since been making enquiries and apparently 40 to 45mpg is what is expected from the car, so I guess I'll have to live with it.

Have since posted a new thread for something else, which thinking about it, I should probably carried on this one.
details below.
http://forums.mercedesclub.org.uk/showthread.php?t=30231

 

[Nuclear Bob]

Hi, my C220 coupe is manual, so probably unlike most others, but I regularly get between 51 and 55 mpg, (indicted up to 62mpg) and over 700 miles to the tank, Unless I'm in a hurry I usually change up at around 1800 rpm, quite smooth and no hunting. However, this mpg has increased from last year at the same time, I was getting 2 or 3 mpg less. Any clues as to why? My driving habits haven't changed much in 40 years.

 

[Legoman]

probably the drag factor of the rain effect we have had this year lol

 

[W203-C220]

Hi, my C220 coupe is manual, so probably unlike most others, but I regularly get between 51 and 55 mpg, (indicted up to 62mpg) and over 700 miles to the tank, Unless I'm in a hurry I usually change up at around 1800 rpm, quite smooth and no hunting. However, this mpg has increased from last year at the same time, I was getting 2 or 3 mpg less. Any clues as to why? My driving habits haven't changed much in 40 years.

Is this still the case Bob?
I have a theory that as the MAF ages it gets dirty, works less efficiently, losing oyu the turbo boost that means the car tends to rev less freely, change up sooner etc. But I would love to suffer your extra few mpg - as would many others ;-)

 

[djb]

However, this mpg has increased from last year at the same time, I was getting 2 or 3 mpg less. Any clues as to why? My driving habits haven't changed much in 40 years.

maybe still on last years tyres, now more worn,so less flexing tread loss?

engine more bedded in ?

high fuel costs leading to unconcious less use of the loud pedel?