Thread: aem ems using o2 feedback in boost

i was curious if anyone does this, like tune the map to pretty close then uses the o2 feedback to fill in the gaps in boost over 0.93psi- say 20psi

the off boost is pretty straight forward but the aem ems pda guide says that its possible to use the o2 feedback in boost with a wideband becuase it reads the afrs quicker than the factory o2 sensor but was wondering if it were safe to do or if it worked

it should work no problem. its recommneded on the ems forum to use o2 feedback to actually tune the car. figure out what afr you want make a run and tune with the feedback value.

well my map is pretty close tuned up to 1 bar, however i turned the boost up to 22lbs and the fuel map out of the tuned portion is going into the low 10s so i was thinking of tuning the o2 feedbck to fill in the gaps after 14lbs

I've never liked the idea because wideband feedback is usually set up to work properly below boost. If it's set up that way then it will be too slow reacting to help while in boost. It could cause oscillations of AFRs that you don't want. It's also usualy very easy to get rock solid AFRs in boost without wideband feedback.

That's my experience anyway.

what about the auto fuel mapping on the aem how do you feel about that

Not sure I'm familiar with that. Like an auto-learn mode that tunes the fuel map based on your target AFR map? I've always skipped them at the beginning but they are good for fine tuning at the end depending on the algorithm...
You can also leave them on to act like a factory ECU that always "learns".

If that's not what you were talking about then just ignore me. =]

haha no yeah that is what i was talking about, kinda like a learning ecu based on a arf target

Well, the less sophisticated Emanage Ultimate works pretty well on getting target AFRs with the autotune function. You just type the target AFR in the desired RPM / TPS or Load cell and does a pretty decent job, then you manually take it from there.

So my guess is AEM should be worth for initia tuning too

you can set your car up for boost comp if you already have it tuned to 1 bar. Boost Compensation tuning explained (again) MicroSecBit too!
basicaly your setting your fuel map the same once you hit boost for each column (the rows should look the same from 1psi up) and using throttle and boost fuel correction tables to add or remove fuel for that amount of boost.

good idea i will read up on it more, i definitly like the boost comp or automapping idea to correct the fueling issues