How do I increase fuel economy in stock VS-II

[slayer208]

Hey fellas,
I'm trying to figure if I can increase my fuel economy in my VS-II. It's totally stock and now has near 240,000K's on the clock. I've had it since new, but over the last few years i've been unable to spend the big bucks on it to keep up the maintenence as well as I should "due to major health problems and 2 totalled knees!". On average she clocks around 550K's per tank but as we're using it a lot more now because we're trying to cut down the usage on the poor old honda i'm finding the fuel bill is around 30% more on the commodore that what it is in the honda. 550K's per tank on a massively undersericed motor is probably pretty good, but I generally drive it like an old person unless iv'e gotta overtake someone that's going slower than me along the highways which happens on most days. Although the honda is an 05' model, we've clocked near 160,000K's on it already and it's already starting to fall apart not to mention the roads here are quite bad, narrow and full of pott-holes. I've just done my first major upgrade to the car by doing the VT big brake upgrade on the front and that has worked out nicely.

I know she's due for a major service so I might start there. I have just installed one of those supercharged-type GM intake systems with a hi-flow pannel filter and have cleaned out the entire throttle body and intake system with throttle body cleaner. I have also just brought a new memcal with the 10 GM updates. Apparently this will cause my car to run more responsive, smoother and should increase the fuel mileage by around 50K's per tank. I haven't noticed any major economy difference from running straight unleaded compared to premium but it does seem better on premium.

I haven't been able to do any real servicing on the motor except for the engine oil and oil filter change which I had done around 3,000Ks ago. The plug leads are original since new, the battery's got a dead cell and if left for 5-7 days the car won't start. I haven't had a chance to change the plugs and trans fluid for around 70,000km's and have never had the injectors cleaned since the last major service my holden in around 2002 at 90,000Km's. Car has been hard to start the last 40,000k's but i'm certain that's due to the old bad spark plugs. Also noticed that one of my plug leads has touched the exhaust manifold and that may be causing her to run slightly rough.

I'm hoping to get the old girl back to where she was originally where I was able to clock 700-800K's on the one tank of juice.

Hopefully replacing what i've mentioned will make a difference. If you've got any other tips to help the efficiency of my engine i'd be happy to know!

Cheers Fellas!

 

[IBLOWN]

550 kays to a tank? Jeez your going well! What is that highway driving? City driving will only see around 380 kays to a tank. 65L that is.

 

[slayer208]

Yeah, I guess 550 isn't too bad but no-where near what she was when she was new. Most of my mileage is sort of country highways, although the roads are quite terrible and there are some very slight inclines. My driving conditions are a little mixed as the forst 30K's are windy narrow dodgey roads followed by about 40 k's of highways with some slight bends, another 10K's of windy roads followed by a clean run of about 70K's of reasonably good highway. Our roads here in Tas are really shocking in some places and recently some world class engineers came to rate tassie on its infrastructire. Our roads got an 'F' rating. Guessing the F means F*&^ed! lol. Where I live i've got probably the worst roads in the entire state from what i've seen.

 

[slayer208]

Wonder how she'll react on fuel economy now, now that it has the GM CAI, Hi-flow pannel filter and new updated memcal. Doesn't seem to run excessively rich on cold starts now and has lost that fuel smell. Driving it around it seems to run better and more refined. Idling has improved a lot also.

 

[bandidoben]

change all fluids.
coolant engine oil trans oil.
change spark pulgs spark leads
with premium there isnt any point running your car on it as your car is tuned from factory so the only bennefit of using premium is to the oil companys.
make sure your battery levels are up aswell. if it has a dead cell might not hurt to get a new one.
check wheel bearings if they are causeing rolling resistance that will add to the fuel consumpion as well (not heaps but every little bit counts)
clean the maf out aswell
and also would hurt to replace the oxy sensors as i guess they are still the originals to..

i have no trouble getting 7-750 out of a tank of fuel highway driving in my vs.

 

[BottleFedVS]

as for using premium fuels, The computer will adjust the spark to get the best out of the fuel your using.
The only thing is it takes 2-3 tanks of fuel for the computer to realise it has better fuel & over the 2-3 tanks if you keep using it your milage will improve.
i have actually proven this for myself on a 100km road trip when I was commuting to and from my work in the city.
I used the trip computer on my wifes VR 5.0lt Calais.
I would put 3 tanks of Fuel through the car then the test tank.
with 91ron (regular unleaded) i used 15L/100km
with 95ron (Premium Unleaded) i used 13.8L/100km
with 98ron (BP Ultimate Unleaded) i used 12.2L/100km

The only only fuel I use now days especially when I'm chasing economy is 98ron.
as I said, I done those tests for my self & thats how my mind was made up.
I hope that helps in some way.

 

[Brett_jjj]

I get heaps better economy when using 98 octane fuel.My VSV6 runs like crap on 91 octane fuel and it uses a lot more of it too,which in the long run ends up costing me more than when I use the 98 stuff.

 

[bandidoben]

if your car is tuned to run 98 ron then of corse it will run better on it.
stock VS from factory is designed for 91ron.


this has been argued 1000s of times.

 

[Brett_jjj]

if your car is tuned to run 98 ron then of corse it will run better on it.
stock VS from factory is designed for 91ron.


this has been argued 1000s of times.

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.

 

[BottleFedVS]

Well fyi my wifes VR 5.0lt Calais is stock from factory.
The computer does self adjust on its own to a small extent.
"From factory" 98ron was not available until after LRP (lead replacement petrol) was canned in 2000.
so unless my wife went and got an aftermarket tune when I was driving the car constantly & was broke I am wrong.
Read about the tunning of the PCM/ECU & it will tell you that the computer adjusts itself to a small extent when it comes to the spark.
The car used fror the test was & still is 1995 VR Calais 5.0lt 165kw auto (NO Modifications whatso ever!) that was purchased in January 1998.
at the time it had 195,000km on the odometer.
It now has 288,000km on the odometer.
This is just stating the facts.

not meaning to sound grumpy or upset.
I appologise if this has come across as agressive, it is not meant to.