Emissions test for MAFless OTR CAI?

[Gravity]

Hi all,
in this thread I was talking about the RTA (NSW) regulations related to installing a MAFless CAI. An engineer told me it'd require an emission test to be considered roadworthy.

I'm curious if anyone has actually done an emissions test on a MAFless and what the results were?

Related to this, something I can't work out is how does a MAFless car adapt when the ambient temperature varies, or air density (due to humidity or altitude)? Or does it simply not adjust.

- G

 

[dmacey]

The MAF



MAF fitted to a GM engine in a Holden Commodore - a wire mesh screen is normally installed across the front of the MAF to smooth airflow across the wire elements
The MAF is a component in a vehicle's intake system through which air flows past a wire that is heated by an electrical current. The airflow cools the wire, enabling the MAF to calculate the mass of airflow into the engine. The vehicle's engine management computer then uses this information to calculate the correct amount of fuel to be delivered to the cylinders by the fuel injection system.

Removing the MAF

When tuning a MAF-equipped vehicle to operate in MAFless mode, the MAF is removed. This requires the use of an alternative method of calculating airflow into the engine. On vehicles so equipped, this alternative involves the use of a manifold absolute pressure, or MAP, sensor. The MAP sensor measures pressure in the engine's inlet manifold. When coupled with data regarding the engine's revolutions per minute, or RPM, and throttle position, the MAP sensor can be used by the engine management computer to calculate fuel requirements.

Advantages

By changing the engine from MAF mode to MAFless/MAP mode, vehicle modifiers claim two advantages:
The MAF may pose a physical restriction across the vehicle's intake tract, thereby reducing airflow into the engine. By removing the MAF this restriction is eliminated, potentially improving engine performance.
By moving the airflow measurement sensor from the intake plumbing to a point closer to the cylinders, the time lag from air moving past the sensor to reaching the cylinder can be reduced, thereby improving throttle response.

When you retain the MAF but get a MAFless tune, the MAF is still used as a temperature monitor suppling further information to the ecu

 

[Gravity]

That's helpful.

 

[dmacey]

I have spoken to OzTrack about your concern with meeting emissions regulations.

Steve told me categorically that with a tune, it would pass.