402 Auto Engine Performance and Driveability
Copyright by Goodheart-Willcox Co., Inc.
18. An exhaust gas analysis shows a high CO reading
and a low O2 reading. Technician A says that a
defective purge valve on the evaporative emissions
canister is the cause. Technician B says that low fuel
pressure is the cause. Who is correct?
(A) A only.
(B) B only.
(C) Both A & B.
(D) Neither A nor B.
19. A vehicle with multiport fuel injection has excessive
emissions and a rough idle. The scan tool readings
shown below were captured at idle. When the engine
speed is increased, emissions decrease to normal and
the idle smoothes out. Which of the following is the
most likely cause?
(A) A defective ignition coil.
(B) An open injector harness wire.
(C) A sticking PCV valve.
(D) An EGR valve pintle not fully seated.
20. A vehicle with multiport fuel injection has failed
a state air-quality test. The test results are shown
in Figure 18-11. Technician A says that low fuel
pressure can cause these readings. Technician B says
that a leaking fuel pressure regulator can cause these
readings. Who is correct?
(A) A only.
(B) B only.
(C) Both A & B.
(D) Neither A nor B.
Ignition timing (°BTDC) Base timing: 8 Actual timing: 25
Coolant temperature
sensor
212°F/100°C
Idle air control
valve
23 percent
Open/closed
loop
Open
Fuel pump
relay
On
Malfunction indicator
lamp
On P0300, P0403
Diagnostic trouble
codes
Evaporative emission
canister solenoid
Off
Torque converter clutch
solenoid
Off
Data Scanned from Vehicle
EGR purge valve
solenoid
23 percent
Intake air temperature
sensor
82°F/28°C
Manifold absolute pressure
sensor
1.8 volts
Engine speed sensor
680 rpm
Brake light switch
Off
Cruise control
Off
A/C compressor clutch
Off
Knock signal
No
Vehicle speed sensor
0 mph
Oxygen sensor
0.53 volts
Battery voltage
13.4 volts
Throttle position
sensor
0.68 volts