Very Bad Fuel Economy VT V6 Problem.

[Z2TT]

Hi.

I've got a VT and have been getting very bad economy, there is no error codes.
The car chews up petrol like crazy even for just light highway driving.

The Engine is in very good condition, starts in one crank and has very good compression,
no smoke or anything like that. O2 Sensors are new.

in 50km of mostly highway driving, it used 1/4 of a tank up. The car was at 1/2 way when i began driving,
and then the gauge was at 1/4 when I traveled 50km.

Does the VT Fuel Guage normally begin going down much faster once it's reached a certain point? Other than that I'm not sure what could be causing it.

There is no misfiring or anything like that. Before I take it to an Auto Elec or EFI Specialist I just thought I'd ask if anybody else has had an issue like that.

Only other thing i could think of is a Fuel leak, can't smell anything but perhaps there may be some areas that are common faults?

It's a 1997 VT Wagon 3.8L V6

Cheers.

 

[accentstencil]

Which brand of O2 sensor are they? Some of the cheapies are not much chop.

 

[Cheap6]

Accurately recording the fuel use would be a start. "1/4 tank" to go "X" distance isn't at all precise. Fill the tank (to cut off), record the odometer reading or zero the trip meter, drive for a few hundred km's refill, and make note of the fuel volume added to refill the tank . It's best to do that a few times because there can be quite significant increases due to heavy traffic, A/C use, short trips from a cold start and differences in the fill cut off point between different fuel bowsers.

If there is found to be high fuel consumption and the O2 sensors are OK: Look for stains around the injector 'O' rings and fuel hoses. Also consider the fuel vapour venting hoses. When were the spark plugs and leads checked/replaced? Tyre pressures OK (~32psi - higher is OK up to the pressure limit on the tyre sidewall)?