Was doing average 15l / 100km but now doing 21l / 100km

[Puffwagon]

The comments point to the o2 sensor/s or a fark up in calculating.

 

Instant fuel consumption can get very high. 1000cc or so injectors x 6 is 6 litres a minute at 80 to 100%dc. 99.9 L/H is tame. It's closer to 300 L/H which is where the gs34x runs out on our cars.

[Rab]

99.9 instant on the screen isn't unusual.

[k31th]

^^

[El Andrew]

To explain o2 sensor cause (if that what it is) they sit in your exhaust and measure the o2 levels to make sure that the AFR going into combustion chamber are correct. Ie if the car measures x going into the engine, the o2 measures y on the way out to make sure they correlate.

 

When the sensors get bad (which just happens over time) they may give a false lean reading and tell the car to add fuel, hence the increased consumption.

 

Someone with more knowledge might be able to confirm this, but I'm pretty sure this adjustment shows up in the long term fuel trim. If you check this and it isn't close to zero you might have an o2 sensor issue.  Only about $100 and easy to fit.

 

I also reckon its the front one that could be the issue, which is what compares what went in to the engine with what came out. I think the rear o2 sensor is more about whether the cat is working properly. I've got a BA which doesn't have a post-cat sensor so don't quote me on that.

[OZYWALKER]

9/10 times the tuner will disable the rear o2 sensor as it will throw codes if you have a high flow cat.

[EvilDaifu]

Okay thanks for that info El Andrew - that helps my understanding alot   

 

I'm pretty sure the exhaust manifold bolts were checked and tightend during the service.  I remember reading somewhere about checking for exhaust leaks.

 

Also - I'm thinking giving the K&N air filter pod a good thorough clean (it looks off-white now rather than mostly black) will actually help now as that's where the air is coming in.

 

I'm not sure if F6 have high flow cats so not sure about that OZYWALKER.

 

Starting to think it is 02 sensor related now or if its operating okay - something affecting the air hitting it.

[Rab]

28 minutes ago, EvilDaifu said:

I'm not sure if F6 have high flow cats so not sure about that OZYWALKER.

You won't have if you're able to flash back to stock and still drive (or at least you shouldn't drive with stock tune with a cat)

 

Any chance the average included country miles from the original owner and your stop/start city driving is only now catching up?

 

Only real way to be accurate is to keep a log of kms/fuel. Go back to your full tank and filling after 1/3rd gone etc (will cost the same and any "dodgy fuel" is diluted by the rest of the full tank, rather than concentrated in the almost empty tank.

 

Any real issues should have been picked up last week by Mick??

 

Reset before the weekend and see how it reads after a while. Should be closer to or under 10l/100 for the trip over.

 

That said - 21l/100 is way high for your car.

[Box stock T.]

45 minutes ago, Rab said:

That said - 21l/100 is way high for your car.

Especially for the fact its pretty well unmodded. Just a flash tune done.

[masda74]

would unplugging the battery for 10 mins to reset the computer also help?

I also think it is an 02 sensor, but only filling to 1/3 of the tank, might be contributing too.

[Rab]

Flash tune probably gets better economy than stock tune