VZ fuel consumption 18.0L /100 help

[jack.higgins]

My 05' VZ SV6 is showing 18.0L/100. out of a nearly full tank i have tripped 250kms. This is not normal, does anybody have any suggestion to as what the problem is? I have had it checked at a mechanics and nothing was found?

 

[Nut Kracker]

The o2 (Oxygen) sensors are usually associated with poor fuel economy.

 

[jack.higgins]

so the o2 sensor can cause your fuel economy to cut in half?

 

[jack.higgins]

so the o2 sensor can cause your fuel economy to cut in half?

 

[XioiX1983]

+1 for O2 sensors, they don't always throw codes either, well mine didn't, iit went form 22 ltr per 100 km, down to 15 ltr.

Also check plugs,coils, fuel/air filter, clean maf/throttle body and check for manifold leaks.

 

[vzwagon]

I had my plugs, fuel and air filter changed and it helped improve my fuel economy it wasn't a drastic change though

 

[Mattde]

another +1 for the O2 sensors. give them a good clean out, couldn't hurt to give your MAF a good clean too.
Clean oil counts for a lot too, not sure about it helping with fuel economy but it will certainly help with performance in general.
If you can afford a new Manifold gasket it couldn't hurt to pull it off and clean it out with some carby cleaner and give your throttle body a good cleaning too.
Might not help heaps but its worth a shot?
What kind of fuel are you using?

 

[TAILS83]

I find my vz is in closed loop a lot(using a Bluetooth obd2 adaptor to see its in closed loop). Even under moderate accelerator meaning it's using all the sensors including O2 sensor to control fuel/timing.
If your O2 sensors are buggered then so will your fuel economy. Depending on which model vz you have you may have 4 O2 sensors.

Other than that try cleaning maf, clean air filter, spark plugs, or worse case blocked cats/exhaust.