spence7

Hi

Is it true that there's a difference in the ECU's between the MY93 cars and the MY95s ?

Such that it's more capable of taking 95RON fuel without problems ?

Or is this a myth !?

Alex

jonny gav

iTrader: (1)

both ECU's are mapped for 100 ron fuel so i myself wouldn't use anything less than super.

i use optimax and NF octane booster in my MY95 wrx

Dave R

All 92 cars and some 93 cars had a map that gave 220 ps, while most like to think all 92-94 cars were 240ps, but hey ho..

95/96 saloon WRX's are 260ps (Z4) EcU. Yess all mapped for 100 RON for best performance,

BUT I ran my 94 WRX on 95 for 3 years and not a whimper, so although 97/98/Optimax is best, don't worry too much.

Chris.Palmer

The Prodrive PPP ECU for Pre MY97s is based on the WRX 95 ECU, it recommends SUL as a minimum.

There is very little differences in the Fuel & Ignition maps for 93 & 95 wrxs.

I'd always recommend SUL as a minimum - even better Optimax or SUL + booster.

Chris

spence7

thanks chaps. Much appreciated.

I guess I should strive for an absolute minimum of SUL then.

OK here's a question, if I use 98 for a few weeks so that the ECU has fully adjusted the iginition timing to the correct degree, and I then stick 97 in it, will it think oh **** and back it right off such that it has to slowly slowly advance the timing until it hits the correct settings for 97 ? Or will it back off slightly and not take so long ?

Wonder how long it actually takes to fully adjust from scratch to say 98. Cos this means if it does back the timing off, then whilst it's still in learn mode, one should take it easy !

Chris.Palmer

The early ECUs tend to retard fairly quicky, but re-advance very very slowly. Hence, the frequentlty reported performance gains after an ECU reset.

Having said that, it does requre quite extreme conditions to trigger a permanent drop in boost or retard of ignition etc.

My personal recommendation is, better safe than sorry, I always carry some octane booster just in case I can't get Optimax (98 RON - my chosen minimum), SUL (when I can add a small shot of booster), OR 95 RON (where more booster is required).

Having said that I run my car pretty much on the limit of boost & knock, and there are occasions where I know I I've over stepped the mark slightly & the ECU has protected the engine, by reducing boost or advance. After these minor lapses I perform an ECU Reset as a matter of course & try not to make the same mistake again.

It is worth stating that I try to run to the max, take the gamble & are fully aware of the consequencies.

Chris

RiSKy

my car's a my95wrx with the 240ecu, would the 260ecu fit on mine, would it be a straight swap, or was there any other modifications made by Subaru to make the 260 model?

Mine's only boosting to .8/.85 bar at the moment, someone on here mentioned that some of the 240's had an ecu glitch? So i'm thinking of changing to the later ecu as a fix, would this work?

Roy

Dave R

Yep. The 95 saloon ecu is a Z4. STI's of the same era are 6K and 7K. You can pick 'em up for around a ton and they plug straight in. More power and smoother delivery. Might be a bit lumpy for the first 5 miles but fine after it's 'learnt'...