RomRaider

So it seems when i travel from my home town @ 700m ASL to sea level my turbo'd wagon needs like an extra 7% more fuel to compensate for the dense air. But unfortuently it doesn't look like anyone has defined the table in question for me to compensate for the altitude change. I'm running a wrx 2.5bar MAP sensor on the car with the addition of a turbo so kind of a danger to my manifolds or more likely the pistons when boosted.

Can anybody help with this please??
Assuming it would be Atmo compensation for the MAF scale?

Thanks,
Dave.

I've never heard or read about Atm.Pressure compensation for the MAF sensor. From my understanding of how a MAF works, it shouldn't be necessary anyway.
My guess would be that you just need to compensate with your right foot.

Boost is ok? There's quite some compensation there usually.

So when a wrx with its factory tune a sea level climbs a hill.. it’s stock afr of 10.5 at full noise goes to 9.6 or 9:1 because there’s no Atmo comp. your joking right!?

No, stock wrx wouldn't do that. And as far as I know, Underbraker is right.

You probably just reach uncharted territory in your tune - higher g/s and thus g/rev - different cells in open loop table. Combine that with MAF scale that is not tuned past the point you reach above sea level and there's your error.

Logs and more info would be helpful. How did you arrive at 7% AFR error?

as above, if this was a speed density tune then yes you'd need compensation but the MAF sensor should be accurately reading the amount of air coming in unless the IAT's are significantly different as well.

Log data will be the way forward here to see what's happening.

The reason I say this is my AFR’s where exactly 11:1 at sea level when on dyno on Friday last week and when I got home I am now seeing AFR’s in the 9’s.

what IAT were you seeing tho as well and what gear did you dyno in vs what gear are you logging in now and what IAT's ?

also that's quite a big drop in AFR - is it possible you've sprung a boost leak and that's what is throwing it - check the LTV info see if there are any clues.

I've had a look into your ROM, and i saw Open Loop Fueling targets in the 13:1 to 12:1 range. Looks like an NA map to me. Has this been tuned?
Also, the open loop table only scales to 2.0 g/rev load. Not sure about your setup, but you most probably reach higher loads.

Anyway, something is off here. My first guess would be MAF and/or injector scaling.

Try to get your car closer to the AFRs you command in the ROM. But first you should also make sure your fueling targets are adequate.