Automobile Electrical and Electronic Systems, 5th Edition

Engine management

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9.2.7  Warm-up time

A signicant quantity of emissions produced by an average vehicle is created

during the warm-up phase. Suitable materials and care in the design of the

cooling system can reduce this problem. Some engine management systems

even run the ignition timing slightly retarded during the warm-up phase to heat

the engine more quickly.

9.2.8 Exhaust gas recirculation

This technique is used primarily to reduce peak combustion temperatures

and hence the production of nitrogen oxides (NOx). Exhaust gas recirculation

(EGR) can be either internal as mentioned above, due to valve overlap,

or external via a simple arrangement ...