Is the EJ20K 6S ECU ok on 91 octane Gas

nicbinc · 11-11-2010, 09:42 PM

I have a 97 EJ20K STI with the 6S ecu. I am currently in the middle of a rebuild due to a failed rod bearing on #2 piston. (Big Surprise right an ej20k with a bad rod bearing) Hopefully the rest of the parts get here Monday and I will start a build thread. But first I have some questions.

Background: I bought the car as an unfinished swap for an unreasonably low price. I finished the wiring and drove the car for about two weeks while trying to figure out why it didn't rev past 4K. Turns out it was a bad maf $350 later idles revs and pulls perfectly. Well it did for like a half hour after which it developed a terrible rod knock. We tore the engine apart and found the #2 rod bearing nearly obliterated and maybe a quarter inch of slop.

So after I get this back together will i be able to run the car on my 6S ecu. As far as I know the best pump gas you can get readily around here is 91. So did our gas kill my engine or is there something that is just worse about the 20K. I literally only did 4 1st and 2nd gear pulls after installing the maf.

Options: 1: Run the car on the 6S (Which I plan to do for the break in as i wont be boosting.)
2: Get a power fc. Super cheap for full standalone, but no tuners nearby and I could be worse than a stock ECU
3: Emanage Ultimate. Cheaper seems to be good.
4: smt6 cheap good piggyback that does what I need retard and fuel.
5: SDS engine management. $1500 installed and dyno tuned locally. But pretty basic.

So what should I do? At this point I don't want to run any crazy mods or boost, even though I'm building the block for the option to. Won't the stock ecu sense knock pull timing and be fine? I like the idea of the stock ecu but I don't want to do this again, and I would like to autox. What if I replace the boost controller and run less boost? What about revs with a 11mm oil pump can I take it past 7K now and again.

Thanks for the help all you subie gurus.

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Poppie · 11-12-2010, 11:03 AM

The standard ecu needs 97 RON minimum but i understand in the US you work out fuel ratings slightly differently (average of the RON and MON?) or AKI?

The knock sensor can only tell the ecu to pull timing to a certain degree if it still detects knock after that point the engine will start detonating and you'll need to rebuild it.

Power FC has no knock correction and is quite old now.
In the UK most people shy away from piggyback ecus perhaps becuase we may have more option.

11-11-2010, 09:42 PM	#1
nicbinc Scooby Newbie Member#: 262698 Join Date: Nov 2010	Is the EJ20K 6S ECU ok on 91 octane Gas I have a 97 EJ20K STI with the 6S ecu. I am currently in the middle of a rebuild due to a failed rod bearing on #2 piston. (Big Surprise right an ej20k with a bad rod bearing) Hopefully the rest of the parts get here Monday and I will start a build thread. But first I have some questions. Background: I bought the car as an unfinished swap for an unreasonably low price. I finished the wiring and drove the car for about two weeks while trying to figure out why it didn't rev past 4K. Turns out it was a bad maf $350 later idles revs and pulls perfectly. Well it did for like a half hour after which it developed a terrible rod knock. We tore the engine apart and found the #2 rod bearing nearly obliterated and maybe a quarter inch of slop. So after I get this back together will i be able to run the car on my 6S ecu. As far as I know the best pump gas you can get readily around here is 91. So did our gas kill my engine or is there something that is just worse about the 20K. I literally only did 4 1st and 2nd gear pulls after installing the maf. Options: 1: Run the car on the 6S (Which I plan to do for the break in as i wont be boosting.) 2: Get a power fc. Super cheap for full standalone, but no tuners nearby and I could be worse than a stock ECU 3: Emanage Ultimate. Cheaper seems to be good. 4: smt6 cheap good piggyback that does what I need retard and fuel. 5: SDS engine management. $1500 installed and dyno tuned locally. But pretty basic. So what should I do? At this point I don't want to run any crazy mods or boost, even though I'm building the block for the option to. Won't the stock ecu sense knock pull timing and be fine? I like the idea of the stock ecu but I don't want to do this again, and I would like to autox. What if I replace the boost controller and run less boost? What about revs with a 11mm oil pump can I take it past 7K now and again. Thanks for the help all you subie gurus. * Registered users of the site do not see these ads.

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11-12-2010, 11:03 AM	#2
Poppie Scooby Newbie Member#: 262422 Join Date: Oct 2010 Chapter/Region: International Location: Dorset,England Vehicle: 1998 V4 Type R Feather White	The standard ecu needs 97 RON minimum but i understand in the US you work out fuel ratings slightly differently (average of the RON and MON?) or AKI? The knock sensor can only tell the ecu to pull timing to a certain degree if it still detects knock after that point the engine will start detonating and you'll need to rebuild it. Power FC has no knock correction and is quite old now. In the UK most people shy away from piggyback ecus perhaps becuase we may have more option.