205/215/246 - how do they handle lower octane?

underscore

Well-known member
For those of you with any of those engines/guys with 205 electronics, how well do they handle lower-grade fuel like 91 or 89 octane? Not for doing WOT pulls to redline but just for normal driving around, does it still run smoothly in a pinch or is it completely gutless?
 

lalojamesliz1

New member
I'm running a 205 and it runs great with the pee pee 91. I don't go easy on my cars either. that's why I always try to get it running 100%
I've been pushing 17-18 psi and it deffinetly pulls much harder than the low setting of 11-12 psi on my ebc. I have a large H/E and my bosch pump and fan are always on though. Ever since I replaced my KS wire all my code 52 issues went away.
 

CMS-GT4

Active member
I know the uk 205 ecu is tuned to run on lower octane. The jdm ecu is set for 94 ron if I remember correctly.
I use a 205 ecu with sheel 93 octane and the car runs fine. I have not seen how it runs with higher octane fuel. Some mr2 guys claim they run 91 in California with 3rd gen swaps.

There was a dyno shootout in the UK at one point and I think they claimed the UK versions 205 made more power because they were tuned for the proper fuel, where the jdm version was making less power due to the lesser fuel.

I am curious if the st246 was de-octaned for Malaysia. The bulk of them went to Malaysia.
 

underscore

Well-known member
That's good to know, I'm guessing a UK/JDM ECU swap is plug and play? If nothing else someone could swap to the UK ECU when they know they won't be getting the best fuel.
 
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