R34 Gt25 auto terrible fuel economy

[Hobbs]

Hi guys, this is my first post so hopefully I can find some answers. My automatic r34 gt25 is giving me terrible fuel economy and my petrol tank seems too small. A full tank from empty only takes 30L, and from what I’ve read a full tank should be from 50-65L. 25L got me 150km with regular driving. I don’t know what the problem is since I know the tank shouldn’t be that low, faulty gauge maybe?

[GTSBoy]

Obviously the gauge is faulty.

Hi fuel consumption is most probably borked O2 sensor. Could be damaged exhaust (crushed), blocked cat (unlikely), dirty air filter (highly likely).

You should be able to get 10s driving around in the suburbs in an NA auto.

[niZmO_Man]

i'm guessing intake leak + sensors like AFM not working properly + some sort of fuel leak, like the hose coming out of the tank is not fully sealed.

[Hobbs]

Ok I’ve since replaced the oxygen sensor, installed a high flow cat. Fuel efficiency is much better but still somewhat inefficient, a full tank from a quarter above empty is around 40 (wasn’t filling up all the way last time) and I’m getting about 350km.

[GTSBoy]

Check fuel hose under car near tank, near filter in engine bay, etc, for cracks that could be letting the fuel out.

[joshuaho96]

On 5/19/2022 at 11:54 PM, GTSBoy said:

Check fuel hose under car near tank, near filter in engine bay, etc, for cracks that could be letting the fuel out.

Not a bad idea at this point, here's what mine looked like:

[Hobbs]

Ok cheers, will have a good look tomorrow