I have had my 3.8 for about six months now and put about 9000 kilometers on the car. In this time, I have an average mileage of about 12mpg. This is mostly city miles and the occasional trip.
Firstly is this normal? If it is, what then will account for a consistent deposit of soot at the ends of the exhaust. I know that this should mean that the car is running rich. This is why I want to change the oxygen sensor. So secondly, where would I find one in the U.K. It is the easiest place for me to look. I tried europarts online but I do not know the part number so it was no use.
So if anyone has the part number for the oxygen sensor and idea of how much it is. Please let me know.
I have had my 3.8 Touring for about the same time and can say that I have about the same milage as you, but a fair bit better on longer trips. My exhaust is also sooty, so i suspected a damaged O2 sensor, but after testing it (Bently procedure) it seemed OK.
I think the city driving milage for this car is terrible (observed throught watching the on board computer).
I get about 21 mpg overall from my 1995 6 speed 3.8, per tank. (Normally around 310 miles per fill). On a long journey, I have seen 28 mpg on the computer, and had done over 400 miles on a tank before the low fuel light came on..........the 6 speed with 70,000miles on it does more to the gallon than my previous 1992 5 speed with 164,000 miles on it. Makes sense really.
Hope this helps.
Mark
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1995 3.8 6 speed - gone, but not forgotten.
1999 Land Rover Discovery Td5 ES
I doubt your oxigen sensor is faulty, fuel consumption in slow moving traffic with the aircon is terrible on an m5, especially if you accelerate hard in stop start traffic ( the weighs a lot remember )
When the oxigen is faulty usually your engine runs like a pile of ****e, especially on idle, and none too clever the rest of the time.
its also quite likely that it would bring up a warning to check engine as the engine management wouild revert to limp home mode on fixed values.
With the introduction of lead free petrol all cars that run on it will have a sooty black exhaust regardles of wether they run lean or rich. this something I have confirmed on one of my previous cars that could run on both fuels.
its very important (in order to improve the life of your engine)
that you take some time out of the city and give the engine
a chance to "breath" properly.
Hell, it even says in the owners manual to allow the engine to breath "above 3000rpm" for some time after running around in
traffic.
I agree with everyone else...around town the pipes are sooty,
but i avoid it !!
On a fast motorway they revert to a better grey colour.
So will that then be that I need a new oxygen sensor? Seeing I get 12 mpg or about 18 kilometers per liter. P.S. I have no visible air leaks. :confused
My fuel consumption driving dring to work and back in traffic is 17 or 18 litres per 100 kmh, when i do long journeys I can get better fuel consumption i had it down to 11 litres per 100 kms if i drive like and old lady, but usually travell at 200 km/h on motorways and dual carriegeways its back up to 16 or 17 litres per 100 km
. Not sure about town driving as I try to avoid it.
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