1.33 Vvti Fuel

[avensis57tr]

Whilst waiting for the Yaris to arrive have been reading that the 1.33 vvti has the highest compression ratio of a stock petrol engine as a resuult I wondered if it benefits from using super unleaded 97+ ron instead of standard fuel? Or if it is designed to use premium unleaded. My Fabia 1.2 TSI certainly benefits from premium unleaded as running on 95 ron has apparently cause problems for others and have noticed causes running to be rough, the petrol flap also says 95 premium as a min but don't know if this is due to it being direct injection and turbo charged. Any opinions?

Thanks :)

[alfiejts]

You'll only get any bnefit out of higher octane fuel if you have a sophisticated engine managment system that detects pre-ignition via knock sensors in the cylinder block and adjusts the ignition timing to get the best out of the fuel used (or some sort of switch you can set under the bonnet as on some old Vauxhalls...)

I don't know for sure, but I can't believe that the Yaris ECU will be so sophisticated - it'll just be optimised for regular 95 RON fuel in the UK and so won't gain any benefit from a higher octane.

I've certainly tried it on both our 1.0 and 1.3 Yarii and it made no difference to the fuel consumption.

I do put a tank of Shell Optimax through approx once a year - becuase even if the extra octane isn't any use, it has more sophisticated detergents in it and I have the idea that the engine and injectors will benefit from a "spring clean" once a year.

What a lot of people do say, is that you shouldn't use "supermarket fuel" all the time. By all means use it now and then but use a branded fuel regularly.

My brother runs a motorsport tuning company and he gets loads of cars coming in with rough running issues caused by using nothing but supermarket fuels. The basic fuel they use is the same, but the supermarkets cut down on costs by using fewer "additives" in the fuel than you get in branded fuels, so the engine and injectors get more clogged up inside...

Fortunately, I have a Shell garage nearby that price-matches my local supermarket, so I can always use "Shell".

Their new better standard fuels seem to have made an improvement in fuel consumption too. Worth trying out...

[avensis57tr]

Thanks, think we will just stick with 95 ron, my mum wouldn't be too happy about paying extra for super unleaded anyway lol. Agree with you about the supermarket fuel run my cars on the bigger branded fuel which have the other additives currently using Shell v-power. Will try and keep the Yaris on Shell fuel as well and stop my mum using morrisons like she does at the moment suspect this is why the diesel Avensis she is trading in only gets about 43 mpg plus she drives it like a petrol.

[Raeman]

I do as Alf says, once a year treat it to some "Posh Petrol"

You could allways throw in a bottle of redex injector cleaner every now & then. I use it on all my vehicles, never had any issues and allways get good MPG.