Will the ECU not automatically compensate for UK fuel?
Aitch
Not in a position to be absolute here, but having discussed this with a lot of people including Japanese from tuning-related fields the answer seems to be a resounding no.
The standard ECU in most mass-produced cars ( eg most Toyotas) will be set for the spread of fuels within the target country.
My local Toyota here in Japan dealer assured me that the engines in my Celica GT4, Soarer etc will handle all available fuel RONs in Japan, ie +/- 98-100.
With certain more highly-sensitive cars (Subaru turbos etc) there is less flexibility even within that spread. A Japanese Subaru dealer here in Japan told me the other day that if I buy an Impreza or Legacy turbo here they recommend using only 100 octane fuel. The ECU will not compensate, they were saying, even within Japan. The Subaru dealer in London said they recommend remapping, but it would be alright if I didn't intend to push the car.
Many aftermarket Japanese-mapped drift machines have been sent to the UK and blown up. The tolerances at the upper end would therefore seem to be much finer. The Japanese guy I use to tune my engines here in Japan is absolutely clear on this issue about the danger of fuel purity/volatility? between countries.
Whether this is a simple RON gap problem, or whether it is also to do with fluctuations in the absolute guaranteed purity of the pump fuel at any stated RON, is an on-going debate.
Either way, if I wanted to do silly things with the engine, then a remap would have to be a serious consideration.
There is a current theory that without a remap you can keep topping up the octane with boosters. I was told, however, that if you have the lower re-map done, then it doesn't matter so much if you subsequently put higher octane fuel in. I would be interested in any comments on this!
All of the information above is opinions I have collected over the years, and you are free to use, correct, or discard as necessary! :thumbsup:
