I have just learned that my car has got normal lower ron petrol in it after my brother borrowed my car off me. Now there's not much left in there but has he(or have I, as I gave it some stick earlier) caused any damage to the engine? Obviously my unichip is mapped over GTEC2 therefore I am slightly worried but I'm gonna crawl around until it completely finishes rather than mix it with optimax but have I got anything to worry about?

Can't answer your question Easy, but have one of my own, can the Gtech II only run on optimax or any high ron rated fuel such as ultimate, tescos 99, etc?

Yes that is correct as in simple terms, it has a miminum ron rating that it will only run on (without causing damage hehe) and that is 97 I think so therefore anything above it is fine. The only difference between the actual fuels is that some are apparently cleaner ie. the optimax but how true that is I'm not sure.

Cool, fitting mine on monday so i need to know these things <img src="/forum/images/graemlins/crazy.gif" alt="" /> <img src="/forum/images/graemlins/laugh.gif" alt="" />

Which fuel do you normally use out of interest?

ultimate or optimax <img src="/forum/images/graemlins/laugh.gif" alt="" />

If your Unichip has been mapped with the G-Tec II using Optimax then it is likely that the ignition has been advanced just a couple of degrees shy of detonation. Now this may run throughout the rev range but the biggest danger is when on full boost at the top end due to the increased charge temps. If you subsequently run pikey fuel then you run a much greater risk of detonation so the smart move is to drop the boost to lower charge temps. You could always dump a bit of octane booster into the tank but I would get as much 97-98 ron fuel in there as possible. If detonation takes place then the knock sensors should tell the ecu to back off the ignition until it is safe but you can't rely on this 100%

I would put 10 litres in now and run it as low as you can and then top up with optimax to fuly dilute it and use as much of the cheap frud as possible <img src="/forum/images/graemlins/smile.gif" alt="" />

Any coupe should always be run on higher octane fuel, esp those with chips or ones that have been mapped based on optimax etc.

If *ever* having to use 95RON in an emergency I would always then take it nice and easy and more or less stay off boost.

Basically I'd be having words with your brother <img src="/forum/images/graemlins/wink.gif" alt="" />

Better to completely fill the tank with optimax etc or chuck in some octane booster. Running it dry could create other problems.

Agree, you should run your car at the minimum RON your car was mapped at, sounds like it was BP/Ultimate.
If you're stuck in the outer Hebrides <img src="/forum/images/graemlins/wink.gif" alt="" />, and all you can get is 95 RON then all you do is run on minimum boost then fill up with the other when you can.

joe