Page 170 - Understanding Automotive Electronics

2735 | CH 5 Page 157 Tuesday, March 10, 1998 11:10 AM

THE BASICS OF ELECTRONIC ENGINE CONTROL 5

the important engine variables are mass air flow, fuel flow rate, spark timing,
power, intake manifold pressure, and many others that will be encountered in
this chapter.

Inputs to Controllers

A variable is a quantity Figure 5.6 identifies the major physical quantities that are sensed and
that can be changed as provided to the electronic controller as inputs. They are as follows:
the engine operates. 1. Throttle position sensor (TPS)
2. Mass air flow rate (MAF)
3. Engine temperature (coolant temperature) (CT)
4. Engine speed (RPM) and position
5. Exhaust gas recirculation (EGR) valve position
6. Exhaust gas oxygen (EGO)

Outputs from Controllers
Figure 5.7 identifies the major physical quantities that are outputs from
the controller. These outputs are
1. Fuel metering control
2. Ignition control
3. Ignition timing
4. Exhaust gas recirculation control

Figure 5.6
Major Controller
Inputs from Engine

UNDERSTANDING AUTOMOTIVE ELECTRONICS 157