Fuel Economy bad

[Leebo]

hey guys i have a 1989 VN V6 standard motor right, It has such very poor fuel economy not that it worry's me to much it's a V6 i know that.

But it's very out of control like 180kmsor less to a tank. Not like a big motor using big amounts of fuel, that would be normal you would expect that but my car is drinking it like some sort of fuelaholic.

i have noticed the O2 sensor is broken do you think replacing this will bring it back.

any suggestions would be much appreciated thanks guys.

[Haydz]

if your oxygen (02) sensor is broken that would probably be the cause of most of your problems.


also people have found a new coolant temp sensor brings their fuel economy back into a manageable range.

hope you work it out mate

[TVR-190]

also try a new fuel filter, and a CAI / kn filter doesnt hurt.

[delcowizzid]

and new plugs gapped at 1.5mm and some good leads.dead O2 sensor will definatly make it drink the juice too

[pjdm1980]

If your O2 sensor is buggered it will tell your computer that your engine is running lean so the computer dumps max fuel to try to fix the lean problem.

[Leebo]

okay cheers guys that is a great help.

so in order of response: Where is the coolant temp sensor so i can check this?

I have a new fuel filter, VS supercharged cold air intake with K&N filter.

cheers guys

[leigh 7005]

also check your petrol tank for holes.my car was using heap of fuel i put $30 bucks in to go to work and on the way there it was in the red only just made it and it was like 20-25 km away.

[Leebo]

yeah when i last had the car up on the hoist i noticed the fuel hoses were wet and got some petrol on my hands and thought that's not right.

glad you reminded me I'll look into that.

[Leebo]

I just put on a new O2 sensor i got from the wreckers and no check engine light is showing that's a pleasing outcome for my car lol.

I will have to see now how she drinks fuel.

[anarklov3r]

Also, if your car isnt warming up, Id look into replacing your thermostat. If your thermostat is constantly open, water flows through the engine too fast for it to even warm up.

When your engine is cold, your engine will run rich to try and warm it up. So if it thinks its always cold, its always going to run rich.

That along with your leaky fuel pipes and dead O2 Sensor would appear to be the problem.

My 1991 VN Wagon with a VP motor in it is getting ~15Litres/100km and thats driving very heavy footed. Thats with new O2 sensor, new thermostat, full service (new oil, air and petrol filters).

[pjdm1980]

okay cheers guys that is a great help.

so in order of response: Where is the coolant temp sensor so i can check this?

I have a new fuel filter, VS supercharged cold air intake with K&N filter.

cheers guys

I tried to fit a vs CAI and the bonnet wouldn't close on my vp i think there different

[centy]

heat the ends of the cai and squash them down so the bonnet closes.

[Leebo]

yeah mine is a genuine one i ordered from Holden. those repco ones are a bit sketchy.

mine fits just fine but you cannot drop the hood on it i have to put it down the close it with my palms.

Thanks anarklov3r i will check those things you have recommended i new O2 sensor might not be the end of it.

however if there's no CEL anymore with it come on if any of those things you said are broken or not. Is this why you may have to check them separately?

[88GreenVN]

I just put on a new O2 sensor i got from the wreckers and no check engine light is showing that's a pleasing outcome for my car lol.

I will have to see now how she drinks fuel.

I'd say you will be very happy you did this Should drop it below 15L/100

A VN in top nic will get around 10-11l/100 around town.

[Leebo]

yeah i only on my L's so i obviously don't drive with a heavy foot so i will have to start the trial when i fill it up next and reset the clock.

[anarklov3r]

I'd say you will be very happy you did this Should drop it below 15L/100

A VN in top nic will get around 10-11l/100 around town.

I did everything i can think of (except CAI) and im getting 15L/100km hehe. Im assuming the 10-11 is daisy driving?

[tigervh]

I did everything i can think of (except CAI) and im getting 15L/100km hehe. Im assuming the 10-11 is daisy driving?

Nope I get about 12L/100km out of a manual 5ltr and that's smashing it everywhere. A V6 VN should do 10-11/100 easily.

[88GreenVN]

I did everything i can think of (except CAI) and im getting 15L/100km hehe. Im assuming the 10-11 is daisy driving?

No not at all. The Greenfoam tune and all the sensors replaced. The 88 wagon is 10.6 and the 89 sedan is 12. The 89 swdan has a miss in the engine - valve probably.

If you are not getting 12 - something is still off.