Broken Diff?/Bad Gas Mileage?

First off, I have a 91’ Silvia with a Sr (redtop). I recently have been getting horrid gas mileage (200-250kms/tank without hitting boost at all). I’ve changed the fuel filter (last year aka, so maybe 500kms on it), changed the spark plugs, and recently did the O2 sensor (87’ 300zx turbo) hoping it would solve my problem. So far nothing, it still is eating gas. Any other ideas?

Also I have been having this clunking noises when turning slowly either left or right. Its always when I’m under 20km/h and happens more often when I am at a tighter angle. Turning to the right seem to make this noise happen a lot more then the left… It also feels like something is binding, you can feel a very strong vibration when starting off (only when turning left or right). The noise ONLY comes from the rear end as well. I don’t have a 2 way/1.5 way, I have a VLSD.

Any help would be appreciated.

ty befor you post check the shit out i told you to check out trouble shoot for gods sake remove the drive shaft and check your ujoints check shake the yoke on your diff after that then remove your wheels and check axel/ hub play, if you didnt find anything remove diff cover and take a better look .

Already checked everything but diff yoke and diff cover. lol

do you have hicas?

I just want to confirm that you rewired the o2 sensor when you put it in. The 300z o2 sensor plug will connect, but the wire order is different.

Still sounds like o2 to me.

Darek

yes, and there is a lock bar in there.

I rewired it by color, since the two plugs were different.

you sure the lockbar is tight ???, sometimes they can back off

I know its tight, I checked it the other day.