Exhaust Emission Test for Diesel
    Engines (without OBD)

Assignment

Those were the days!, when a Diesel engine was considered to be well adjusted when the driver's open door didn't vibrate too much. Apart from that, the exhaust emission test was, more than likely, a visual examination. For the manufacturers, everything was also okay if the filter was only 50% blackened. What a difference there is today, where the soot from vehjcles with a particle-filter is practically non-detectable.

Function

A pre-condition is - also for the avoidance of engine damage - once again, an oil temperature of 80°C. Apart from the possibilities described in the emission control program for petrol engines, for Diesel engines with fuel injection pumps there is also the clamp transducer, which should be attached as early as possible to a straight, shiny, metal part of the injection feed-line and then not twisted or turned again.

For this emission analysis a warm-up period and calibration is also necessary. This device must also be calibrated regularly. The actual analysis however, runs off completely different than with a petrol engine. The engine must be accelerated up to full-load against it's own mass-inertia and held in this state for a period prescribed by the measuring instrument. During this test-phase, the exhaust gas is examined for clouding. There is only one lamp and a photo-diode without filter, which measures the amount of light coming through on the other side of the exhaust gas flow. Thereby, apart from the black particles from the fuel, also the blue particles from added and /or burnt motor oil are detected. 06/10