I am not trying to rename this place BrisHyundai (It really doesent have the same ring:D ) but theres a little something concerning me with me new car.

I posted a while ago about the fact that I was benefiting loads from using high octane fuel (The higher the better). Only thing is I have noticed is when I'm using it, the engine idles from cold very roughly and vibrates hard. Once warmed up or on the move, all is well. MPG is actally down on high octane fuel, but the performance increase is very noticable.

If I switch back to 95, the idle becomes normal, and the other one we have (same engine) allways uses 95 and idles smoothly

Is it safe to keep using it or will this vibration be harmful?

I am not trying to rename this place BrisHyundai (It really doesent have the same ring:D ) but theres a little something concerning me with me new car.

I posted a while ago about the fact that I was benefiting loads from using high octane fuel (The higher the better). Only thing is I have noticed is when I'm using it, the engine idles from cold very roughly and vibrates hard. Once warmed up or on the move, all is well. MPG is actally down on high octane fuel, but the performance increase is very noticable.

If I switch back to 95, the idle becomes normal, and the other one we have (same engine) allways uses 95 and idles smoothly

Is it safe to keep using it or will this vibration be harmful?

Can't resist.

Just don't tell the ladies or there won't be any high octane fuel left.

How high octane fuel should work - The higher octane rating allows you to run more vacumn advance (presumes the engine has a knock sensor on it), which will allow the engine to run more efficiently by completing combustion closer to Top Dead Centre, and thus increase Brake Mean Efective Pressure, hence increasing torque, and allowing you to run slightly lower throttle settings for a given speed, improving fuel economy unless you make a habit of using the extra power.

Unless the Getz actually has a knock sensor, then 99octane petrol is just "snake oil".

Reports I've read conclude high octane fuel is a waste of time and money in smaller engined cars as the ECU's can't adapt to it... in some tests it actualy reduced bhp in 1.2 & 1.4 engined cars

Reports I've read conclude high octane fuel is a waste of time and money in smaller engined cars as the ECU's can't adapt to it... in some tests it actualy reduced bhp in 1.2 & 1.4 engined cars

If you check here

Hyundai | Choose | Getz | Technical

It says my car does 0-60 in 13.9 Seconds, and with 95 octane fuel this is about right,

This video is when it was running on Tesco 99RON, 11 secs, 2.9 Seconds off the 0-60 time

If I go back to regular stuff, back to about 15 seconds

This was one on a perfectly flat road on my way up to my work which is PRIVATE road

Video of Getz 1.4CDX Automatic - Photobucket - Video and Image Hosting

as allreay stated by KenO, it's a matted of iginition timing at idle, high octane fuel 'burns' more quickly so the ignition timing needs to be retarded a little to compensate, but the amount of adjustment available is very limited, so i guess that it cant adjust it's own settings enough for the higher octane fuel hence the rough running at idle

as allreay stated by KenO, it's a matted of iginition timing at idle, high octane fuel 'burns' more quickly so the ignition timing needs to be retarded a little to compensate, but the amount of adjustment available is very limited, so i guess that it cant adjust it's own settings enough for the higher octane fuel hence the rough running at idle

That makes sence, but will the extra vibration cause damage, thats what Im getting to

Your ECU probably can't advance the timing to get a benefit from premium fuel. Like I've posted on here a hundred times, if it says use 95, use 95! You WILL get LESS power and poorer economy using 97/98/99/102/whatever if your car is not designed to run on it, which yours is not.

That makes sence, but will the extra vibration cause damage, thats what Im getting to

if it does it a lot i would stay away from using premium fuel..... the vibration you can feel is probably the onset of pinking (pre-ignition) and this will cause a lot of damage to psiton rings/valves/ and can possibly in some cases cause the head gasket to blow

if it does it a lot i would stay away from using premium fuel..... the vibration you can feel is probably the onset of pinking (pre-ignition) and this will cause a lot of damage to psiton rings/valves/ and can possibly in some cases cause the head gasket to blow

Yeah, it goes right through the steering wheel,

Advice taken, thanks for your help:thumbup:

I get more MPG on the regular anyway