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DRIVEABILITY - NGC
P0171-FUEL SYSTEM 1/1 LEAN —
TEST
6
Turn the ignition off.
Connect a Vacuum Gauge to a Manifold Vacuum source.
Start the engine.
Allow the engine to idle.
Note: If engine will not idle, maintain a constant RPM above idle.
With the DRBIII in Sensors, read the MAP Sensor vacuum value.
Is the DRBIII reading within 1 of the Vacuum Gauge reading?
Yes → Go To 7
→ Replace the MAP Sensor.
No
7
Note: For this test to be valid, the thermostat must be operating correctly.
Note: This test works best if performed on a cold engine (cold soak)
Ignition on, engine not running.
With the DRBIII , read the Engine Coolant Temperature (ECT) Sensor value. If the
engine was allowed to sit overnight (cold soak), the temperature value should be a
sensible value that is somewhere close to the ambient temperature.
Note: If engine coolant temperature is above 82°C (180°F), allow the engine
to cool until 65°C (150°F) is reached.
Start the Engine.
During engine warm-up, monitor the ECT Sensor value. The temperature value
change should be a smooth transition from start up to normal operating temperature
82°C (180°F). The value should reach at least 82°C (180°F).
Did the ECT value increase with a smooth transition and did it reach at least 82°C?
Yes → Go To 8
→ Replace the Engine Coolant Temperature Sensor.
No
8
Check for any of the following conditions/mechanical problems.
AIR INDUCTION SYSTEM - must be free from leaks.
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
ENGINE PCV SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connected to
correct injector
Are there any engine mechanical problems?
Yes → Repair as necessary.
→ Test Complete.
No
ACTION
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.
Continued
102
APPLICABILITY
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