Milanche

Hello!
I have a EUDM 5th gen prelude with a F20A4 engine, it has an OBD2 ECU, i plan on using the SAFC only at Hi-thrtl setting (over 35%) and i have read that the ECU will learn the correction of the SAFC and i will be able to enjoy it only for a short amount of time... Do i need to do the OBD2 workaround mod, or does the ecu learn the corection only in closed loop (under 35% thrtl) i cant find the article for OBD2 workaround anywhere so could use some help and if someone could explain the learning of the ecu a bit?

Thank you!

 

alphajesse

It will only do it at part throttle running in closed loop.

If you only tune the SAFC at high throttle, you'll be fine.

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Milanche

Thank you for a very clear answer!

Milanche

Oh one more question, will there be any problems if i set the hi thrtl settings at lets say 50%, and the ecu goes to open loop at 33%? So at normal driving the ECU will do its job normaly, but if i decide to go heavy on the gas the SAFC will do its job...

alphajesse

That is the proper way to do a SAFC/VAFC.

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marcucci

Keep in mind, unless I don't know the OE code well enough, the ECU goes open loop at a set MAP value, not at a set TPS value. 100% throttle may throw it into open loop, but I know at lower RPMs it doesn't seem to be TPS specific but rather MAP specific.

What I've derived at is around 30-40% throttle is where it will go open loop (pretty much any RPM/load). I generally set VAFCs to 33%/34% for the lo/hi values. Only tune for the Hi setting as you note, any Lo settings are bound to be corrected for VERY quickly.

I've also found that at least the H22 ECU barfs all over itself when you add fuel. With as little as 4% added mine stumbles all over itself, but with as much as 18% pulled out it does OK. Be careful, though, as high values may throw off the timing map. IIRC on the H22 the number is somewhere around 18% of a MAP shift will put you on a different timing number.

Of course, your F20 is probably mapped a little different, so your mileage may vary.