fuel consump. problem

[Scooter79]

Ive just got back from getting my car serviced 2day where I had both o2 sensors replaced as well as resetting the ECU. Before the service i was using around 14L/100k so im hoping that will go down by 1-2L.

Please let us know what sort of difference the o2 sensors make if any.

 

[LeFtBehinD]

Please let us know what sort of difference the o2 sensors make if any.

Will do, got just over half a tank left so I guess i should start measuring it again when i refill to really test it. Could be a bit of a wait

 

[mikemutlow]

This fuel consumption issue is real interesting; it is clear that actual consumption is very dependent on driving conditions but I find it hard to understand how your figures can be so bad - unless there is something funadamentally wrong with the engine management system (e.g. O2 sensors) or you are driving continuously in traffic and have a lead foot! My 98 VT (only 90000kms) is used daily to take me 75 kms each way to work and back. This involves 20km stop-start on the freeway, then about 5 km through town (lots of lights) then about 50km on the freeway which is relatively clear but still involves a fair bit of road works i.e. slowing down / speeding up. I get on average 8.5 L/100km and at least 800kms out of a tank. This is manually calculated each time I fill up and confirms (within a couple of %) that the computer readout for fuel consumption is correct. When cruising at 105kph with the cruise control on the readout is averaging 7.5L/100km; at 95kph this drops to about 6.5L/100km and at 85kph down to about 5.5L/100km. So speed and driving style are hugely significant, but this car is capable of delivering very economocal driving. It is actually better than my Subaru Liberty (2.2L) which I thought was good and delivered 8.8 L/100km over the same conditions. I reckon you must have a fault somewhere which should be fixed and would not waste any money on so called fuel saving devices as all my research (look at US Federal Trade Commission website ) shows they dont work. What does work and costs nothing is gentle accels, regular servicing, tyre pressures kept high, air con kept off, roof rack off, excess weight out (e.g. toolbox or golf clubs in the boot) etc, etc. These can easily deliver 20-25% improvement and this has been proven!

 

[pj]

If the car is running quite well, then the oxygen sensers are the most likely cause of bad fuel consumption.

 

[pj]

If the car is running quite well, then the oxygen sensers are the most likely cause of bad fuel consumption.

 

[LeFtBehinD]

Ok sorry for the late post but it seems it hasnt made too much of a difference. After i filled up im still using about 13.5L/100k

So i dunno... :S

 

[MTX_15inX2]

hey well i dunno why but my vr gets about 420km out of a tank that town driving and about 550 to 600 on the highway so iam guessing thats good and i was complaining about that now i wont complain about it now after your problems

 

[filtnineee]

only 300 kay thats way off, im doing alot of city driving and i get around 400 for 50 liters, so prob get at least 450 from a tank, but freeway get way over 600, get ya fuel injecotors cleaned.

 

[VrBerlinawgn]

maybe try not to floor it so much...LOL!!

Injectors won't cause it (if they're leaking your idle will be stumbly) I'd say buggered MAP sensor or manifold air temp sensor dead...

 

[cliffo78]

To those experiencing poor fuel economy in this post:

What is your temperature gauge showing after a normal drive. Does it rise to a bit under halfway (which is normal)? I had a VR some years back that was giving me 300km to a tank with conservative driving. I also noticed that the engine was running cold (ie the temp gauge hardly left the "C" mark) and the heater wasn't very effective. I solved the problem by replacing the thermostat. The reason for the poor economy was that the ECU was running the engine on a rich fuel/air mixture, which it does until normal operating temperature is reached.