sepukku

Working on a custom turbo kit for my 180TTQC.
Just a few questions I need help on.

One quick question.
Does the 1.8t motor use both the mas air and speed desnity at the same time?

or does it use them at different times?

I know you can disconnect the mas air and the car will still run perfect accept for an annoying CEL.

If i use an APEX AFC do i connect it to the mas air or the speed density part...or do i need two of them..where i would use one for each?

Any help would be appreciated.

Audi2ptzero

Problem you will run into is when you max out the maf which does not have that high of a reading in the first place. You might have to go with a 3" maf houising and then use the AFC.

sepukku

So you do not have to fiddle with the speed density maps at all?

Correct me if I am wrong.....but the car will still run perfect if the mas air is removed...which leads me to belive that the speed density is used more.

Please let me know what you think again on this.
Thank you

Audi2ptzero

When you run that way the car just runs on the set fuel maps, if the maps are set to run rich then you will run rich since it was the job of the maf to cut the fuel back during wot.

xr4tic

When the MAF goes bad, the car will run bad, even though the speed density calculations would be OK.

sepukku

Do the mas air and speed density maps coincide...or are they different?

What exactly is the speed density used for if the metering is done by the mas air?

Is it used for open-loop or closed-loop?

xr4tic

Mass Air is the ACTUAL air mass going into the motor.
Speed Density uses RPM, displacement, temp, pressure, and volumetric efficiency to GUESS what the air mass is going into the motor.

Which would you prefer, actual numbers or a guess?

The ECU prefers actual numbers, the speed density numbers are basically a back up, in case there is a total MAF failure, or to check if there are any pressure deviations (like a boost leak)