unleaded or premium unleaded

[EXCESSV]

yeah each to there own champ. i use it too every now and then as a cheap injector cleaner but hey it probably doesnt do that either :bop:

 

[vlv8vic]

Finally! Someone talking some sense!

I tried premium and logged several tanks back to back on my spreadsheet I maintain for my expenses and it didn't show any significant gain in mileage. In the current climate I am not dishing out an extra 10 cents/litre for nothing.

lots of people aren't noticing an increase in power or mileage. what they don't realise is the long term benefits to the cleaner running engine.I've noticed a massive difference in the condition of the engine since using premium fuel. since everything is running much cleaner i have noticed a slight increase in mileage. (that might be after 12 months of use at 2 tanks a week for most of it...)few extra cents doesn't worry me if it ensures my engine runs cleaner, smoother, longer.

 

[jc58nc]

Up until now I've ran ULP because with my own economy tests I found no difference running ULP or PULP, both gave 10 ltrs / 100km on 2000km runs.

But what I did find was with Ecotecs with the blue injectors (02801155777) although you may have had them ultrasonically cleaned and flow tested it may not last long and the problem returns, I had a "code 76" STFT Delta High. A few web sites including onlineinjectors quote to just replace them, not to bother trying to clean them.

I have now changed to running PULP purely for the injector/engine cleaning ability and have also replaced my injectors with a new set, the economy has come up to 8 ltrs / 100km on a short test, but I believe this is to the new injectors, not the PULP fuel. I think the PULP is good insurance for me to try and stop deposits forming in the injectors and get a longer life from them where most of my trips are short and stop/start.

 

[vtsuperchargedboy]

my mate borrowed my car twice and filled it up twice, first time was with 91 ulp and second was 98 ultimate (he didnt tell me until after the 98 ultimate was finished) and the only thing i noticed was that with 91 my fuel needle dropped too quick, with the 98 it dropped much slower.

 

[pablo]

I have read that the engines with 'knock sensors' are many times a second advanced up by the ignition control computer to the point it starts to 'ping' through being over advance, when the sensors detect this the computer retards back the ignitionto the point of no 'ping'. There for the engine is constantly changing its ignition timing every second to be in tune with load, fuel octane, temperature etc. So, by that the donk tunes itself to whatever fuel it is given....What say somebody in the know??

 

[jc58nc]

I have read that the engines with 'knock sensors' are many times a second advanced up by the ignition control computer to the point it starts to 'ping' through being over advance, when the sensors detect this the computer retards back the ignitionto the point of no 'ping'. There for the engine is constantly changing its ignition timing every second to be in tune with load, fuel octane, temperature etc. So, by that the donk tunes itself to whatever fuel it is given....What say somebody in the know??

Close but not quite right.
There's an ignition advance map in the memcal that the timing is normaly set to, if the knock sensors detect a ping then the timing is retarded by a predetermined set amount and will advance slowly until it detects another ping.
If the car does not ping on the current ignition advance map it will not advance any further. When you change from ULP to PULP the ignition advance map can be modified to take extra timing and that becomes the maximum advance point.

 

[pablo]

Thanks for putting that matter straight jc, I remember reading about it some time ago, but forgot exact details. What can be done to change memcal map to tune for prem fuel? does the memcal have to come out of the vehicle to be re-programed by a specialist tuners computer?
Pablo

 

[Torquative]

I think it works in reverse too

for instance Ive used Ultimate in the VX Ecotec for the past 12 months since I brought the car second hand, just to give it a good clean out and so on.

But Ive noticed on the odd week there (I get a week out of a tank) where Ive had to fill up with normal ULP because of price or because Ultimate has run out and I need fuel, the needle goes down super quick.

I'm told its because the engine is burning the fuel too quick because its mapped itself for the higher octane 98. It also runs like a dog, hard to believe the difference.

Is this true??

 

[jc58nc]

Thanks for putting that matter straight jc, I remember reading about it some time ago, but forgot exact details. What can be done to change memcal map to tune for prem fuel? does the memcal have to come out of the vehicle to be re-programed by a specialist tuners computer?
Pablo

Correct, this is where Dr Bob works his black magic on the timing map and the gearbox change points if you are an auto:thumbsup: