Can't understand it???

Running in a new STi7, filled up first two times with 95 ron (had a fuel card. Produced 33mpg, and no problems with the smoothness. However, I recently filled up with optimax for the last two tankfuls. This has resulted in no better performance and 24mpg?????? The driving style and speeds have been exactly the same, any answers??

 

Either way, DO NOT use 95RON fuel in an STI unless you wan't to see it det and die. Luckily if you are running in and keeping below 4K and not labouring the engine you most likely haven't done any long term damage.
Even UK model STIs have to be reprogrammed to run 95RON reliably.

Isn't there are warning on the fuel cap saying use 97RON or higher?

 

you see this is why dealers need shooting sometimes!! You ask specifically about it, and your told the ECU resets itself to cope with 95, or 97, or optimax. Thanx for the advice, I'll stick to the full caffeine version!!

 

newer ECUs are more adept at adjusting engine for lower grade fuel.

95ron should be okay if it's a uk spec sti 7, having said that I would still run super unleaded.

paul

 

I thought the type UK could run on 95 RON - the uk car only produces 265 bhp is this not because Prodrive have re-programmed the ECU's ? If it an import STi7 then yes if SUL is available I'd use that. I've run my STi3 on 95 RON for the last 3 years and 20k miles as 97 isn't available where I live and contrary to popular belief it hasn't expired - and I don't take it that easy.

Kevin.

 

Ok guys

You all sound like you know what your talking about...

yes its a Type UK , but can anyone tell me why the mpg difference is so huge?

 

How did you know it produced 33 mpg?

Most convenient way to check is to fill up tank until first click of nozzle, run tank down and refill same way. Then calculate mpg.

Difference between filling up and *completely* filling up can be quite a few litres.

A

 

Me thinks you got ya maths wrong first time of asking. 33mpg sounds way too good. Just for the record, i gained an average of about 2.5 mpg when i changed to using super from 95 ron.