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| new2vn |
Posted - 10 Aug 2011 : 01:09:30 AM
Hi guys, I have a stock 9/1991 S2 VN V6 Auto.
I have been reading about using different octane fuels in this engine.
The workshop manual says stick to 91 octane, but I believe this engine has the capability to run 95 or 98 octane due to the knock sensor.
I am not looking to make my gas-guzzler any more expensive by running premium 98 octane (in SA we are paying around $1.40 per litre for 91 octane), but when working with engines any horsepower or efficiency gains will get you more Ks out of a tank of fuel if you are no heavier on the right foot.
I used to use 98 octane in a different engine I built.
It would get an average 50kms further on 98 octane than on 91 octane (30L tank), which made it no cheaper to run overall. But when I wanted plenty of power I always had my custom jets in a mechanically operated secondary throat of my carb setup. Just tap the accelerator and smokin wheelspin would result, it was outta control, too powerful so I sold it. This engine was much smoother and easier to tune to 98 octane than 91 too.
Does anyone run different fuels in a 1991 S2 V6?
Anybody tried E85 or methanol blends yet?
Cheers, Ben. |
| 10 L A T E S T R E P L I E S (Newest First) |
| Antman |
Posted - 20 Aug 2011 : 09:19:46 AM
That orange engine light should come on with the ignition and go out when started everytime.
If it doesn't show at all you should probably check the bulb.
After a quick google search 12.5l/100km is rated figures (wether that's true or not is another question) of a brand new VN auto V6 around town. So 14 isn't too bad considering the age of these bad boys now.
Don't be afraid to clean the injectors, it really isn't that bad a job.
Way easier then kitting a carby. |
| new2vn |
Posted - 16 Aug 2011 : 10:22:31 AM
Thanks for the tips mate. I have never cleaned injectors before, but I have carried out all my own mechanical work.
(If I want to be charged good money for the privelege of making my car worse I take it to a "mechanic". If I want the job done right, I always do it myself. I am sure there are some good honest mechanics out there, probably on the dole...)
I have experience with all sorts of carbies and jets, I will look into the procedure for injector cleaning.
Strangely, I used to make fuel tanks for Commodores and I know the fuel senders are average at best. My gauge is ridiculous.
I can fit $20 worth of fuel in above the full line.
The top half of the gauge disappears slowly ($25 worth)
The needle gets to the bottom half, swings around everywhere and fuel disappears in minutes! The gauges are sticky too, they suck.
I never really go below 1/4 tank, so its hard to get to the 400k mark on 1 tank.
I just did this instead:
I marked the position of the fuel needle. (about 1/3 tank)
I put 15 litres of fuel in.
I reset the odometer.
I drove for just over 100kms.
The needle has returned approximately to where it was.
So roughly, I am getting 14L/100kms around town BEFORE I get into stuff like O2 sensors. The orange lght did come on twice when I first got the car, only in the ign "ON" position, before starting the engine. When I started it the light went off - I have not seen it since. I assume the ECU will have recorded that as a fault code since the appearance of the orange light, but I have not touched the diagnostic connector yet to find out.
I will pull up the fault codes and see...
Thanks, Ben. |
| MrNutter |
Posted - 14 Aug 2011 : 3:28:43 PM
You should be getting around 500km per tank around town if your not thrashing it. With consumption like yours the most likely culprit is an old O2 sensor. They are located on the exhaust manifold (look for a plug type thing with a wire coming out of it) & help the ecu decide how much petrol to push into the engine. You can get a multifit O2 sensor for about $75 from places like Autone, Repco etc or you can get a genuine AC Delco O2 sensor from Coventrys for just under $100 (paid $98 for mine last month). Replacement is simple though it can be a difficult spot to get leverage in to remove the old one. Spray some WD40 on the old one when the engine is cold & let it soak in before you try to get it out. Don't over tighten the new one or you will have a hell of a time trying to get it out again when it next needs replacing. While your at it I would also replace the air filter & throw in a new set of spark plugs if you havn't replaced them recently. That will make sure you are getting a good air supply & have good spark. It would also pay to remove the injectors & clean them or take it somewhere to get it done if your not confident enough to do the job yourself.
Your fuel gauge sounds off to me, at least compared to mine. When mine says empty I have about 5lt of fuel left in the tank. Possible the sender unit is knackered. Next time it gets low give the gauge a belt & see if it comes up a bit, might just be a sticky gauge. Also try not to go under 1/4 of a tank anyway. Running around with low fuel can cause damage & increases wear to the internal pump so it's always best to make sure there is plenty of fuel to offer it lubrication.
Hope some of that helps you. |
| new2vn |
Posted - 13 Aug 2011 : 10:41:35 PM
Hi guys, I have only ever got about 330-350k tops out of a tank of fuel in my auto V6 VN. It seems to run OK though, maybe the slight miss or whatever it is has become costly in fuel.
The fuel guage reads near bottom, then I manage to fit about $60 or 46L of 91 octane in, then its full. I think I have a 65 litre tank from memory. There must be a pretty large amount of fuel left in the tank when the gauge is reading below the empty line. Is this using too much fuel?
I thought the VN was 12-13L per 100km around town
and 7L per 100km @ 110 km/h highway speeds once the torque converter has locked.
I am not thrashing it either, just smooth take-offs and cruising at 60 km/h. Economy improves a lot on long straight drives with no hills.
Looks like I have to finally get in there and find that diagnostic connector, pull up the codes and go from there... |
| MrNutter |
Posted - 13 Aug 2011 : 12:48:17 PM
Not surprised that there were no noticealbe performance gains. Stock engines (like mine) can't really take any performance advantages out of higher octanes. Need to have a fair bit of performance modifications done before higher octane makes any noticeable difference. I did notice that after a couple of months on 98 my engine started to run cleaner & smoother though. I switched back to 91 to confirm this & the difference in engine smoothness (especially at idle) was noticeable within a week. |
| Antman |
Posted - 13 Aug 2011 : 09:32:57 AM
I used to only use premium.
My odometer doesn't work so can't really state for sure if milage changed at all.
Just didn't notice any change in engine performance when I dropped my standards to 91. |
| MrNutter |
Posted - 12 Aug 2011 : 7:51:48 PM
There's not much to servicing a VN. About all you need to do is oil & filter, plugs, air filter, fuel filter, trans fluid & filter & change the diff oil at the correct intervals. You can reset the ECU if you like but there shouldn't be any need to.
As for the injectors I havn't done a set as yet (like you Ive always been points & dizzy) so I can't offer any advice on performing the job. I have read a couple of tutorials on it though & it seems fairly straight forward so long as you don't rush & do things in order.
Antman, how long did you trial the higher octanes for? The reason I ask is that many people only try one tank full, don't see a difference & revert back to 91. It actually takes a few tankfulls of higher octane before you start seeing a mileage increase. Took about 2 months (bout 15 full tanks) before I saw a real difference in my economy. I went from 550km per tank up to 680km per tank. I didn't change plugs, air filters or do anything else that could contribute to added economy over that period, just the different fuel.
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| Antman |
Posted - 10 Aug 2011 : 10:09:42 PM
I didn't notice any real difference using higher octane fuels in my VG
You can buy "service" kits for the injectors.
Just has the O-rings and a filter. Mine came in kits of 2, so needed 3 kits at $10 or so per kit.
If you have a ultrasonic jewellery cleaner, that'd clean them nicely otherwise make sure squirting holes are clear with wire or something thin and give em a bit of a blow with compressed air
It is a good idea to check fault codes every now and again (some codes don't trigger the check engine light) especially if you're having problems
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| new2vn |
Posted - 10 Aug 2011 : 10:28:14 AM
Thanks MrNutter,
What exactly do you do for a DIY service on a VN? I am used to old cars where there are points and timing to adjust. I have done the obvious things in the VN workshop manual maintenance shedule - changed the filters, lubricants, fluids, plugs, filters etc.
What else do you do during a service?
Do you pull up the fault codes with the orange dash light?
Do you reset the ECU?
There just doesn't seem to be much to do, I can't "Tune it up" like I did with older Holdens. This is good I suppose, I was tired of adjusting points gaps anyway...
I am running on 5 and a half cylinders, checked plugs, leads, coil pack - all OK.
I think I may be dropping a valve, if you put your hand near the exhaust outlet you can feel the exhaust air suck back into the exhaust pipe when it misses.
Maybe I do need to look at injectors, anyone know how to inspect or clean them?
Or do we just replace them these days?
Cheers, Ben. |
| MrNutter |
Posted - 10 Aug 2011 : 08:36:53 AM
You will have no problems running 95 or 98 in your S2. If you are like me & do all your services when you should (plugs, oil change, air filter etc) then you should get increased mileage from using 95 or 98. You will also find the fuel burns cleaner so you get less build up on things like injectors. |
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