610 Review questions see Appendix 2 for answers

1. ABS computers have a good self-diagnosis capacity because:

(a) they work at high speed?

(b) their actual working conditions are difficult to simulate for test purposes?

Fig. 6.23 The electronic unit injector (Lucas CAV)

(c) the braking system stops working if the ABS fails?

(d) the modulator is not under the control of the ECM?

2. A clamping diode is used on some solenoid-operated devices:

(a) to restrict current flow?

(b) to block the voltage spike that occurs when the magnetic field collapses?

(c) to prevent the solenoid connections being reversed?

(d) to prevent overheating of the solenoid winding?

3. Duty cycle:

(a) is the number of times per second that the solenoid operates?

(b) refers to the 'on time' compared with the total time available to operate a solenoid?

(c) is only used on the evaporative purge control solenoid?

(d) is the length of time allowed for the transmission of an ECM command?

4. The electronic unit injector:

(a) has a high powered solenoid that controls the spill valve?

(b) is a single-fuel injector that is placed at the throttle body of a diesel engine and one injector serves all of the engine cylinders?

(c) is supplied with high pressure fuel from a 'common rail'?

(d) is only suitable for small engines?

5. Sequential petrol injection:

(a) uses a single throttle body injector?

(b) has two injectors for each cylinder?

(c) delivers fuel to each cylinder on each induction stroke?

(d) must operate the injectors by pulse width modulation?

6. In the 'lost spark' ignition system:

(a) there is a single ignition coil for each cylinder?

(b) the cycle of operations is completed in 540° of crank rotation?

(c) there is one coil for each pair of cylinders?

(d) the polarity of the spark is the same at all sparking plugs?

7. Stepper motors:

(a) open a valve which is then closed by a spring?

(b) can open and close valves because they can be reversed?

(c) are not suitable for use with computer controlled systems?

(d) operate at very high speed?

8. Exhaust gas recirculation valves:

(a) blow hot gas into the exhaust system to heat up the catalyst?

(b) control the movement of exhaust gas from the exhaust system into the intake system to help reduce NOx?

(c) are not used on diesel engines?

(d) are used to operate exhaust brakes on heavy vehicles?

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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