carlhelv

Hi

My E300TD does an average of 20mpg when it should be doing aleast 30-35
I have had it fully serviced with the air filters changed , only change is the bigger wheels that have not altered the poor mpg on this car , I love the car (7 seater wagon) as I have 4 kids but I was hoping for at least 30mpg on a motorway run.It has done 115 miles and is immaculate , no black smoke on kick down and it runs very smooth (full MBSH)
I dont rev the car hard and find that motorway driving doesnt seem to make a difference , I have booked the car into a Merc delarship this Saturday to see if the ECU is showing irregularities point to the MAF or the car running too rich, tyre pressures are good as they are new wheels with low profile tryes.

any ideas even after drive like "Miss Daisy" as I only get 340miles on a 62 lite take fill up (£58.00) ?
for a deisel this is very poor

Lightman

If I were you I'd first do some real testing...maybe you have..but fill a tank completely to the brim (fuel visible in the filler neck by the cap) and make your runs...when you calculate, use a calculator and be sure to fill to the exact same spot in the neck. Otherwise you can't be accurate. With that said, do a few tankfuls to get a consistent baseline. There is no way to judge by watching your fuel gauge.

How does the car idle - does it knock a lot at idle like a semi truck or is it pretty much smooth and muted? If your mpg is truly off you could have a few different issues - you could have a bad injector or injectors, you could have badly clogged fuel filter or prefilter, or you could have a boost leak somewhere (although you'd typically see more smoke with that). Maf is a good thing to check - they were replaced on both of our E300's around 30-35k miles. It was pretty obvious when the maf went bad though - the car stumbled.. Good luck, and try the 'other' forum in the diesel discussion section....there really aren't any diesel experts here - no offense guys.

carlhelv

Hi

I have checked, double checked and trippled checked !!!!
the filling is definately up to the brim , but alas she is running fuel economy like a E55 AMG

I will ask the Merceds stealership to change the MAF's after the ECU has been reset or diagnosed to a possible fault
I have good clean fule filters with no smell or performance issues with the fule intake and no black smoke, its almost like the car is running to rich, will keep you posted , thanks a million

carlhelv

Hi

I have checked, double checked and trippled checked !!!!
the filling is definately up to the brim , but alas she is running fuel economy like a E55 AMG

I will ask the Merceds stealership to change the MAF's after the ECU has been reset or diagnosed to a possible fault
I have good clean fule filters with no smell or performance issues with the fuel intake and no black smoke, its almost like the car is running to rich, will keep you posted , thanks a million

Lightman

How about injector noise?

I wouldn't replace the maf (just one) unless there is a check engine light or there is a code saying it's bad...

I think at this point scanning codes is probably the best next step..

carlhelv

thanks lightman, will let you know what they find. can any other e300td owners give me some idea on mpg per tank full ?
much appreciated

Harlista

Summerville SC to Little Elm TX (approx 1,200 mi) in 17 hr with average 30 Mph .
Not happy

EdzBenz

Lightman,
What do you mean by injector noise? What type of sound is this? Thanks,

lkchris

You understand of course that this means your odometer is inaccurate and you have no idea the miles you're traveliing.