Emissions And Aftertreatment Flashcards
What are 3 checks a technician can do to make sure a dpf hasn’t been tampered with
Check nox sensor reading
Visual check
Check emissions leaving exhaust
Check delta pressure sensors different
Why do we need engine management
To monitor engine health
To keep environmental impact low
How would you detect a weak mixture petrol mix
White deposits on spark plugs
What gasses come out of the exaust
Carbon, carbon monoxide , carbon dioxide , nitrogen oxide , nox , nitrogen dioxide, hydrocarbons
Why is cetane added to a diesel
It controls fuel burning by controlling auto ignition point
Why is 14.7 : 1 used on modern engines for air to fuel ration
Because it is in the best emissions band and power balance
What does a lamba sensor do
Measure oxygen in the exaust
What are the tier systems for an engine
It is the rating of emissions eg final tier 4 will emit the least emissions possible
What does an egr system do
Exaust gas recirculation, reduces combustion temperature by adding recirculated gas to the intake, this reduces nox gas
What does a dpf do
A diesel particular filter reduces particulate matter to 0.001 microns, pressure sensor on either side to detect soot level, works from 600 degrees
Can work from passive , automatic , parked regen and service regen
What is an scr system
It is a catalyst which mixed def fluid with exhaust gasses aims to reduce nox gas
What is a doc
It is a diesel oxygen catalyst, sits in front of the dpf, reduces pm by 20 % reduces co2 by 50% reduces hc by 50%
It is maintenance free
What is a delta pressure sensor
Sits either side of the Venturi measuring pressure either side
What is a doc made from
A doc is made from rhodium and iridium/ platinum
How would you diagnose any emissions system
Check emissions output compared to input
What shape is the filter inside a doc/ dpf
It is a honey comb shape
What is def fluid
Diesel exhaust fluid is a mix of urea and deionised water
What does the steam create in a scr system
It created hydrolysis
What is an scr
Selective catalyst reduction using ceramic filters and urea and water mixing together aims to have an end result of water nitrogen and oxygen
What does an scr target most
Nox gasses
