Hey,

So I've been running my 1993 Australian delivered SW20 on 98RON for about a year now (previous owner has been using 95RON). It's been running fine, just wondering if the ECU is properly tuned for it stock? Does anyone know anything about this? 
98 will have a different burn characteristic to 91, not just the "knock point" that everyone is aware of. Am I wasting money on 98 and actually *losing* power? Is it worth getting it retuned?

Also, at 3000+rpm, or when the engine is ice cold (some early mornings) I do hear a slight fluttering noise, kind of like a fan belt or something, but it sounds like it's from the engine. Any ideas on that?

As for the ABS, after a track day not all that long ago, I noticed that after the ABS engages and I've come to a stop, something ABS related spools up, then slows back down to a stop. Does anybody know exactly what that is? I'm hoping it's nothing bad, but I can't work out why it could possibly be making that noise.

Any help would be awesome.

Thanks guys.

"Am I wasting money on 98 and actually *losing* power? Is it worth getting it retuned?"
 
For several years I've used 95 RON in my stock gen2 3SGE NA, and it's always run fine.
 
But the owner's manual actually says 95 RON or higher, so if you want to use the more expensive 98 RON the ECU should handle it ok, but could be a waste of money with a stock gen2 3SGE.
 
However I have seen posts on this forum about 98 RON being preferred for the later model Gen3 3SGE's to eliminate pinging.
 
 
 

First ice cold engines shouldnt be revved that high. just let it warm up a bit, like start the car a minute before you plan to drive it..
i would use the better fuel, and probably time to bleed the brakes

Ah right, thought it was tuned on 91 from factory, but yeah, manual says 95. It's a May '93 model, so gen2 engine, yeah?

purple5ive: I mean I hear the flutter at idle when it's ice cold. I *never* push an engine without warming it up first!

As for the brakes, the car stops fine. It's the ABS system spooling up. Not 100% sure how ABS works, does it run off the same reservoir as the brakes? Might be worth a bleed...