Help! Fuel Economy

[sweefu]

Hi,
i have a manual VS series 2. Mods are s/c cai, K&N panel filter, 2.5inch catback mandrel bend with 1 muffler. I am getting around 350k's to a tank on premium, and thats driving 'nicely' changing around 2-2.5 thousand revs. I have just bought a new fuel filter, i'll put that in, i plan to do plugs/leads and new o2sensors. Oil/filter/air filter are about 4000k's old. Could someone please help me by telling me which things to do first to get the most efficiency, and anything else that might help.
Thanks guys.

[PanthaVS]

im driving an auto which should drink more than a manual (if you drive like a granny) and im getting about 450km out of the tank on average. that works out to about 12ltrs/100km.

Also, thats on BP 91. and i do a lot of freeway driving, cruising at 100km and revs about 2100rpm i think? cant remember...

[sweefu]

thanks for your input mate, i live in canberra so its there is alot of 80-60 km/h driving so its not as bad as sydney or anything, any ideas what i should do first or check to try and increase my efficiency?

[PanthaVS]

well the 80-100km/hr is the "cruise" speed for best fuel ecomomy. so driving at 60-80... youd be surprised how your economy goes out the window.

If you do a LOT of stop starting... kiss your economy good bye.

Here's another point... and yes... im opening a can of worms here... but you put premium in it, (98oct i assume) ... yes... it burns cleaner... and yes, its better for the condition of your engine internals... but i have heard it burns slower than 91oct... hence, you should only use 98 if you have the engine tuned for it.

Perhaps your economy will come back with different fuels...? i find my economy can change from different retailers... ie. BP, Caltex, Mobil, etc.... try running consistantly (at least 3 tanks FULL per retailer) and do some note taking...

What i do... when i fill up... i dont fill till the fuel light comes on, then, i fill till i cant put any more in. I reset my speedo, and when i fill up the next time, i get a reciept, write the speedo reading on it, and the economy (ltrs / kms driven x 100) and after 2-3 tanks... you get an average... then try a different retailer...

you get my drift...

[maldotcom2]

If the O2 sensors don't fix it, try some injector cleaner. Aside from that i've heard talk of the fuel pressure regulator being the cause of bad economy.

[sweefu]

If the O2 sensors don't fix it, try some injector cleaner. Aside from that i've heard talk of the fuel pressure regulator being the cause of bad economy.

thanks mate, i'll run injector cleaner next tank, also do you have any idea how much o2 sensors are?
Cheers.

[maldotcom2]

Ebay is your best bet for O2 sensors, just make sure they're 4 wire ones. They're around $50 each. If you go to holden be prepared to bend over.

[Chris E]

Also have got completely shot fuel economy, I would love to get 350ks out of a tank.

My car was an auto (pretty stuffed), O2 sensor was shot, MAP sensor was playing up and just found the knock sensor wasn't even hooked up. I'd be lucky to see 250ks out of a tank, thats just cruising around. Fair enough the car has a cam and a few other bits, but still shocking fuel economy.

I've fixed all the problems with it and have gone manual now, so hopefully will see better fuel economy...

And I was quoted just over 100$ for a new O2 sensor from autobarn. And I'll agree with maldot, holden are just a rip off. Fuel rail O rings - $8 a piece. Couldn't believe it.

[sweefu]

Also have got completely shot fuel economy, I would love to get 350ks out of a tank.

My car was an auto (pretty stuffed), O2 sensor was shot, MAP sensor was playing up and just found the knock sensor wasn't even hooked up. I'd be lucky to see 250ks out of a tank, thats just cruising around. Fair enough the car has a cam and a few other bits, but still shocking fuel economy.

I've fixed all the problems with it and have gone manual now, so hopefully will see better fuel economy...

And I was quoted just over 100$ for a new O2 sensor from autobarn. And I'll agree with maldot, holden are just a rip off. Fuel rail O rings - $8 a piece. Couldn't believe it.

Cheers for the input mate, i found o2sensors for $58each on ebay, so i'll go with a couple of those. After changing my fuel filter yesterday the car is running much smoother and i just filled up, so i'll see how it goes.