Smoke Limiter

A term used in ECU calibration or so called chiptuning that limits excessive smoke during combustion process.

There are four main strategies for limiting smoke:

• MAP based smoke limiter that uses MAP sensor for calculating fuel mixture.
• MAF based smoke limiter that uses MAF sensor for calculating fuel mixture.
• Lambda sensor based calculation
• All modern cars (after 2006) use Closed-loop combustion control that ensures most optimal combustion process. Usually, ECU uses MAP sensor for initial estimate and corrects injection errors via feedback from MAF and Lambda sensor.
  

calibration map of MAP based smoke limiter for VW 2.0 TDi 103kW

MAP based calculation are more reliable in long term but lacks precision whereas MAF based calculation are more precise but MAF sensor precision wears down with time. Bosch MAF sensors durability is 4 years or 150,000km.

3D vief of MAP based smoke limiter