Poor Fuel Economy 2004 C220 CDI Avantgarde

[Toseef]

Hi

I have recently purchased 2004 C220 Cdi Auto with 84k miles on the clock and full Merc Service History. I purchased it on Boxing day based on my successful experience of 2001 C220 cdi coupe. I travel almost 90 miles a day and my previous car 2001 was very good on fuel and used to give 49mpg average to and from work.
Since I bought 2004 C220, it had thermostat issue which has been sorted now and temperature gauge does show correct temperate i.e. around 90, however fuel economy has not improved at all, on long run on motorway it is hardly going upto 39mpg.

Having read several threads, I am of mixed mind that whether this is due to MAF sensors, or Pre Catalytic covertor or something else.

Car overall runs absolutely fine and has got no issue. Gear box is smooth, ad there is a lot of power in engine. No issues with Revs.

I will really appreciate if anyone could give me advice, that should I change or clear MAF and whether this is the real issue??

Many thanks

Toseef

 

[Toseef]

Hi, I am still waiting for experts opinion to my query I raised yesterday. I will be grateful if anyone could look into it plz.

many thanks

 

[geraldrobins]

How long are your journeys? My car averages around 50 but only 40 for the first 10 miles as warming up, this cold time of year.

 

[paul73mt]

have you had it plugged it to get live data from your sensors???? You will also see a lower MPG this time of year with the added winter additives in the fuel but you car should be doing more than that anyway

 

[Toseef]

geraldrobins: My round trip to and from work is 82 miles (30miles motorway, 20 miles dual carriage, and the rest is single carriage). Yesterday with very steady speed and gentle foot on gas, I managed to get 43 average which far below than my previous C220 (parked on 31 December for sale), I used to get 52-54 average for round trip on the same route. Today I was in town and this has given the worst average of 21mpg, again compared to old c220 of 29-31 average in town.

paul73mt: No I have not retrieved any data, however my previous C220 of same engine size and hp I was getting better mpg. I filled the tank from Shell day before yesterday and its going down like anything compared to mileage I have covered so far.

I am thinking of using Injector cleaner? what do you suggest would it make any difference, and which one is best in the market??

Thanks

 

[HollowPoint]

Is this newer car considerably heavier by any chance? A convertible or estate model, where your old one was a coupe? Vehicle weight plays a huge part in efficiency, which is why the brand new W205 C220 is incredibly cheap to tax, because its emissions are insanely low and efficiency is incredibly high and one of the main reasons for this, is because the chassis is considerably lighter than the W204 car.

 

[wemorgan]

If you're 20% down on mpg then something significant is wrong. You can try some injector cleaner, but you're shooting in the dark somewhat. A garage should be able to test injectors, compression etc for you. Frustrating for sure, but a certain amount of trial and error is on the horizon.

ps. you don't have a flat tyre do you?

 

[HollowPoint]

Another possibility is that EGR has clogged up, causes all sorts of issues, including high consumption in some cars.

 

[Toseef]

HollowPoint: It is considerably old car
C220 CDI Avantagrde 4 Door Saloon - Registered in Feb 2004
84000 miles on the clock
1 Owner with full Service History
No issue with Gearbox, or Engine
Revs are fine
17" Alloys
Changed thermostat on 29 December (temperature gauge shows 90).
Agree that weight could be an issue, however average mpg for 4 door Saloon is normally 50+ and in town 30+.

EGR could be an issue, however this has been recently replaced.

wemorgan: U r right, that I will need to visit workshop, but I want to leave that to the last option, bcz I strongly believe that Garage people would cost me fortune. On my previous C220 i had air leak from fuel pipe (from Fuel filter to Ijectors), and was causing problem in start up. 2 garages could not figure out anything, and I managed to fix it myself by simply observing it closely and noticing that where is the leak, honestly it took little push to one of seal, that's it. since then car never had any issue.

 

[Toseef]

Guys, I have retrieved following post from Amazon in review of Redex Injector cleaner. This is based on real experience, so I am thinking to apply this tomorrow as test.

"By JayAhmed on 12 Dec 2014
Verified Purchase
My brothers mercedes c220d which is approximately 8 years old was returning 32mpg in Central london and 41mpg on dual carriageways and motorways. Based on my excellent experience with redex for petrol, i decided to buy this for him along with STP diesel fuel injector cleaner. I used the redex first. I didn't follow instructions, i followed my own knowledge, poured half the bottle in when he had a quarter tank and kept it on D3 (its an automatic transmission) and blasted it on the motorway for 15 mins to give it a boost clean. Then poured the rest in and filled the tank. Admittedly the tank drained faster than usual, but it was expected due to the lubricant of redex. Then, a further tank later, he is now getting 43-46mpg in london!!! WOW! And 54mpg on the motorway and dual carriageways! This is an absolutely awesome product as redex always is."

 

[grumpyoldgit]

Check out Millers Diesel Power Ecomax. They say you can use double dose, which may clean the injectors. Fuel Additive | Performance Additive | DIESEL POWER ECOMAX

I use it in every fill up, as do a lot of others on here.

One other thing, are you going by the OBC mpg or brim to brim tank full and calculating it yourself? The OBC isn't really accurate.

 

[Mercedes man]

Hi was your old car a manaul or auto and what's new one my first 203 manaul c220 cdi y 2001 done 50mpg second 2006 mercedes 203 c220 cdi estate auto done 41 mpg I have a 204 c200 sport estate does about 44.00 mpg hope this helps stew

 

[c220cdi2010]

+1 millers for long term use, plus it is worth also doing a good old fashioned italian tuneup once in a while
also, when you do accelerate hard, do you get any black smoke out the exhaust?

how do you measure your mpg?
should do a full fill up, note miles, drive full fill up note miles and then calculate - onboard should only be used as bodge guide
i have a spreadsheet i update after every fill up so can see over course of many months how it actually fairs

 

[JimBR]

Your MPG sounds very similar to mine - a 2006 C220 cdi estate (manual), I previously had a W210 E220 cdi and that gave fantastic MPG figures on the trip computer ~ 57MPG on the motorway and 35+ around town.

I do not feel that I am putting any more fuel in the C class, I take the read out's with a pinch of salt.

 

[E270 Owner]

Hi
Have you checked your tyre pressures are correct ?

 

[Toseef]

Hi All,

Tyre pressure checked, all are ok and were on 32.
NO smoke whatsoever.
Yes I do have 17inch Alloys but I doubt that they would make this much difference.
I am calculating mileage on actual journey rather than relying on trip computer, but I can see that my car is drinking the fuel like any thing.

I have added Redex ijector cleaner in full tank today, and I got 42 mpg to work and 44 mpg from work back home, but with VERY GENTLE foot on gas. Drove my car on 60-65 mph like old granny. It has done 90 miles in total so far since I filled the tank and I already can see that 1 qtr is almost gone. which means I am estimating that in 62 litre tank I would be lucky to get even 400 miles compared to my old car 525 mils per full tank easy.


I poured 250ml of Redex into full tank, instructions says to use for 2 tanks, however I have added in 1 tank, not sure it was right thing to do, but i am getting irritated when I think of my old car with so much poor mpg.

Will keep you posted with the progress.