Benzdom

I just had service D done - SBC brake flush, fuel and air filters, oil change.

And a transmission service.

I noticed a drop in fuel economy - the opposite of what should happen after servicing.

The drop on longer distances isn't much - possibly 1 mpg.

On short trips it's 3 mpg.

After one mile I still see 10 mpg on my display - a low number I actually have never seen before on my car.

The exhaust seems to smell more at startup now.

The engine heats up nicely, so it's not a thermostat problem.

Is there a chance the fuel mix is too rich - higher consumption and more smell at startup? Would this be something the mechanic would affect by providing a service D?

Thanks!

Benzdom

No reply?

I'm only getting about 13.5 - 14.5 miles/gallon in town (before service it was 17 mpg).

fuel filter was not changed, but the air filters.

Transmission was serviced - seems to downshift a bit too much.

Questions to the mechanic did not give any results.

What could be the reason for a sudden drop in fuel efficiency?

vettdvr

big leak

Benzdom

You mean a gasoline leak?

How could it connect to a service D or a transmission service?

The thing is, driving on the freeway I get to 24 mpg after 15 miles.

It's in the city where the mileage got so horrible, 14.5 to 15 mpg instead of 17 I got before.

Could it be the adjustment of the transmission is bad, so the car uses more gas through shifting at bad points? I noticed the car has now a tendency to shift down a lot.

rodneypierce

Do you by chance have the trans in sport mode instead of comfort?

Benzdom

I don't think I have a sport mode. I have w/s winter summer, and it's on S, just like it was before.

But the shifting of the transmission is probably not great. It had a transmission service, and a change of transmission mount.

Upshifting when you step on it works well.

But generally it seems to upshift too much, resulting in low rpms, and when you step on the gas it either has to downshift, you have to step on the gas more as it's in a higher gear with lower rpm (less torque).

When I roll to slower speeds, it often seems to be in too high a gear, so when it's just rolling I sometimes get jerking movements at low speeds, until you tip on the gas pedal.

Some of the downshifts are not as smooth as before the service.

So I suspect the shifting points aren't well set, and it could explain the poor gas mileage (which is much worse in regular street traffic with lots of shifting, but as soon as I'm driving the freeway (little shifting) the gas mileage goes up to 24 mpg after about 15 miles of driving.

Honcho

Try resetting the the transmission shift points:

1. get into the drivers seat with all doors and windows closed.
2. insert the key on the ignition and turn it into "ON" position. (NOT STARTING THE CAR)
3. press the gas pedal all the way down and hold for AT LEAST 5 SECONDS.
4. while the gas pedal is depressed, turn the ignition key OFF WITHOUT REMOVING THE KEY FROM THE IGNITION.
5. wait inside the car AT LEAST 2 MINUTES WITHOUT opening the doors or windows. then start the car

Benzdom

Thanks for this!

In point 4. did you mean "while the gas pedal is PRESSED DOWN" I suppose?

So I understand the transmission shift points are programmed into the car, and the mechanic actually doesn't have any influence with it...

Honcho

RE: "Depressed" see http://dictionary.reference.com/

RE: "...transmission shift points..." search these forums or Google "Mercedes Adaptive Transmission"

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pinebaron

Depressed could also mean "sad and gloomy; dejected; downcast" though agreeably hard to associate it with a pedal. Can a pedal (and the owner) feel depressed while the pedal is fully depressed? Just not making enough power.

Honcho

I was partially depressed when I wrote that follow up, and considered going "Full Plutoe" on his a$$, but I figured everyone already saw the humor in it.

.

Benzdom

Looks like everybody is pressed for depression.

Let's undepress the gas pedal to depress the depress depression.

boardboy330

Check the air in your tires. If you are like me and run over-inflated tires for better MPG, the dealership mech most likely let air out to be within spec. I always have to inflate after visting anyone.