How do I increase fuel economy in stock VS-II

[lawrencel]

I was getting the same (last week 400kms to a tank) I made the following changes............. now looking at around the 700 to 800kms a tank (really very simple changes)

First issue was the thermostat, it had seized. evident by the very low temp on the gauge, now runs just over 1/4.

Second was the earthing issue with the 02 sensors, see here: https://forums.justcommodores.com.a...nsor-earth-problem-known-holden-problem.98628.

Replaced 02 Sensors

Next change is the high flow SS air intake over the radiator..........

possible next is spark plugs and leads ............. still looking into that one. ie what is worth the expense

then tyres.

am chasing the economy as planning to drive the VS from Perth to Sydney at Christmas and back again..........so every bit will count............. fairly unlikely I will go to extractors, just cant see them making the total difference I want for the price. (ie, not chasing power)

I dont think any one thing will make dramatic changes (once the things that need to be right are right) to fuel economy.......... however some sensible small changes will add up...

gases in, gasses out...........improve that, you will improve fuel economy, cold air induction is the way


Mine is dead stock except for a stage 2 shift kit etc in the auto.

Lawrence

 

[slayer208]

Yeah, first thing I done when I replaced the water pump and all 3 idler pulleys and the belt about a month ago. Also flushed out the radiator and added new coolant. Problem is down here in tasmania that at this time of the year the ambient air temperature will range from 8-12 degrees celsius. The car is very slow to warm up. Nowadays instead of just starting the car and taking off I let it idle for 10-15 minutes first. This gives the car it's necessary time to warm up so I can then proceed to drive, and I think that may increase economy as opposed to driving on cold start or choke. I was getting a real bad unburnt fuel smell out of the exhaust, but have since changed the intake to a GM supercharged-type one, added a new hi-flow filter "original filter was extremely blocked", cleaned out the throttle body and updated the PCM memcal which includes apparent 10 GM software updates to make the engine run smoother, idle better with more economy and power. Also replaced near totally dead ACDelco battery with a 710CCA Yuassa 4x4 battery. With what i've done so far i've totally lost that unburnt fuel smell from the exhaust and the car drives like the engine is more refined. The plugs were last done something like 40,000K's ago from memory and are well overdue. Also, my leads are still the original OEM ones so I might replace them next week also. I reckon this will get the slight miss out of the car as i've got one plug lead that's burnt through a bit. And who knows the state or condition of the original spark plugs. They were only standard cheapies, not like the iridium ones of which I heard will last a good 700,000K's before needing replacement.

Regards!

 

[wortus]

Even with the standard tune theres a heap of difference.If someone runs 98 octane fuel and doesnt notice any difference,then theres probably something elso wrong with the car to start off with.It makes a big difference in mine.I can easily feel the difference in power between the two fuels in my V6,and the economy is way better on 98..As mentioned above,the computer adjusts the ignition timing to suit the fuel.

I've got a VY Ecotech with about 140,000km, it is completely stock and has a factory exhaust and intake and there's nothing wrong with the engine at all and it it runs well on all the fuels I have tried, even with E10 I can't notice any drop in power around town.
I'd hazard to guess there may well be slight power improvements to be had using higher octane fuel but the increases would be slight if the motor is stock. I agree the engine management may be able to advance the spark more using a higher octane fuel but for that alone it's probably not going to contribute greatly to power or fuel use. There are 95 octane E10 fuels around as well. The only time I have noticed my car having noticably more power is on a cold winters night when the air is a lot denser and that's on any of the fuels I have tried including E10.
I drove it to Temora on Caltex Vortex 95 and back home on normal 91 and it got better milage on the 91 octane. Economy is not just L/100km it is the cost to travel a certain distance given the price of 95 and more so 98 the improvement in fuel consumption will still result in a higher operating cost hence worse economy.
My car has a 75 litre fuel tank and it will go well over 900km on a tank of 91 octane fuel on the highway. Last trip it averaged around 7.5L/100km which is what it usually gets on the Hume Freeway.

My local garage has just stopped selling 91 Unleaded so there is just E10 or the premium fuels. Given the extra cost of the premium fuels and increased fuel consumption using E10 at the price difference my first guess is it would still be more economical to use the E10 especially for day to day running around.
Before using any E10 my trip computer was reading about 9.91 L/100km around town and after adding E10 95 Octane 3 or 4 times (mostly aboue 1/2 a tank) it is now at 10.41 L/100km I have not had a chance to compare it's highway economy with E10 yet.

 

[wortus]

It will run just fine on GM plugs and leads which at my local dealership wil cost you about $60 to $65 for the lot. I wouldn't spend the money on the Irridium ones or any other brand of leads. I took my spark plugs out of my VY last service, they were genuine and had been in there about 45,000km and were hardly worn and could have been left in there but I changed them when it recommended. Save your money, same goes with the air cleaner element I get genuine ones for less than $10 and they last 45,000km even at half that distanc eit is cheaper and easier to chuck them away and get a new one than have to worry about cleaning and oiling filters etc.

 

[Autonomous]

Premium fuel is actually 3-8% denser than regular fuels + the very slight benefit of higher grade detergents, so you theoretically will get better economy per litre with premium but the cost negates the benefit.
Also a good tip, fill up when its cold (early morning / late night) as petrol pumps measure volume not density, so the cooler the fuel at the pump the more you get in a tank. Realistically you will get 2-4% better fuel economy, well not really you just get more juice
Use a litres/100km's gauge and keep it low, i try to never go above 12l/100k's and cruising at 90 it runs at around 4-5L/100k's

 

[wraith]

Premium fuel is actually 3-8% denser than regular fuels + the very slight benefit of higher grade detergents, so you theoretically will get better economy per litre with premium but the cost negates the benefit.
Also a good tip, fill up when its cold (early morning / late night) as petrol pumps measure volume not density, so the cooler the fuel at the pump the more you get in a tank. Realistically you will get 2-4% better fuel economy, well not really you just get more juice
Use a litres/100km's gauge and keep it low, i try to never go above 12l/100k's and cruising at 90 it runs at around 4-5L/100k's

Watch out we got a miner here.

 

[Jxfwsf]