Diagnostic procedure
STEP
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INSPECTION
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RESULTS
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ACTION
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1
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Inspect the following:
• Vacuum connection
• Air cleaner element
• No air leakage from the intake-air system
• No restriction of the intake-air system
• Proper sealing of the intake manifold and components attached to the intake manifold; such as the IAC valve, EGR valve (ZJ)
• Fuel quality (e.g. proper octane, contamination, winter/summer blend)
Are all items normal?
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Yes
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Go to the next step.
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No
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Service if necessary.
Repeat Step 1.
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2
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Connect the WDS or equivalent to the DLC-2.
Retrieve any continuous memory, KOEO and KOER DTCs.
If an engine stall condition exists, retrieve continuous memory and KOEO DTCs.
(See KOEO/KOER SELF-TEST.)
Are any DTCs displayed?
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Yes
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DTC is displayed:
Go to the appropriate DTC test.
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No
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No DTC is displayed:
Go to the next step.
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3
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Is the engine overheating?
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Yes
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Go to symptom troubleshooting "No.17 Cooling system concerns - Overheating".
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No
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Go to the next step.
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4
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Connect the WDS or equivalent to the DLC-2.
Access RPM, MAF, TP, and VSS PIDs.
Monitor the PIDs while driving the vehicle.
Are the PIDs within specifications?
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Yes
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Go to the next step.
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No
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RPM PID:
Inspect the CKP sensor and the related wiring harness for vibration and/or an intermittent open/short circuit.
MAF PID:
Inspect for an intermittent open circuit of the MAF sensor and the related wiring harness.
TP PID:
Inspect if the TP sensor output increases smoothly.
VSS PID:
Inspect for an intermittent open circuit of the VSS and the related wiring harness.
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5
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Visually inspect the CKP sensor and the teeth of the crankshaft pulley.
Are the CKP sensor and the teeth of the crankshaft pulley normal?
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Yes
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Go to the next step.
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No
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Replace the malfunctioning parts.
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6
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Measure the gap between the CKP sensor and the teeth of the crankshaft pulley.
Specification
0.5-1.5 mm {0.02-0.05 in}
Is the gap within the specification?
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Yes
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Go to the next step.
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No
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Replace the plate.
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7
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Inspect the spark plugs.
Is the spark plug wet, covered with carbon, or grayish white?
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Yes
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Spark plug is wet or covered with carbon:
Inspect for fuel leakage from fuel injector.
Spark plug is grayish white:
Inspect for clogged fuel injector.
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No
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Install spark plugs on the original cylinders.
Go to the next step.
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8
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Remove and shake the PCV valve.
Does the PCV valve rattle?
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Yes
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Go to the next step.
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No
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Replace the PCV valve.
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9
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Visually inspect the exhaust system part.
Is there any deformed exhaust system part?
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Yes
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Replace the suspected part.
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No
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Go to the next step.
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10
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Install a fuel pressure gauge between the fuel pipe and the fuel distributor.
Connect the WDS or equivalent to the DLC-2.
Turn on the fuel pump using the FP PID in the output state control of the datalogger function.
Is the fuel line pressure correct?
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Yes
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Go to the next step.
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No
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Zero or low:
Inspect the fuel pump relay and fuel pump relay related circuit.
Inspect for leakage inside the pressure regulator.
Inspect for a clogged main fuel line.
High:
Inspect the pressure regulator high pressure cause.
Inspect for a clogged fuel return line.
Inspect the vacuum hose to the pressure regulator.
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11
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Inspect the VTCS operation.
Does the VTCS function properly?
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Yes
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Go to the next step. (ZY)
Go to Step 13. (ZJ)
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No
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Repair or replace the malfunctioning parts.
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12
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Inspect the VIS operation.
Does the VIS work properly?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning parts.
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13
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Yes
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Go to the next step.
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No
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If the A/C is always on, go to symptom troubleshooting "No.24 A/C is always on or A/C compressor runs continuously".
For other symptoms, inspect following:
• Refrigerant charging amount
• Condenser fan operation
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14
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Inspect the A/C cut-off operation.
Does the A/C cut-off function properly?
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Yes
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Go to the next step.
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No
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Inspect the A/C cut-off system components.
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15
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Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side.
Plug the open end of the vacuum hose.
Drive the vehicle.
Does the engine condition improve?
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Yes
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Inspect if the purge solenoid valve is stuck open mechanically.
Inspect evaporative emission control system.
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No
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Go to the next step.
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16
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Visually inspect the CMP sensor and projections of the camshaft pulley.
Are the CMP sensor and projections of the camshaft pulley normal?
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Yes
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Go to the next step. (with EGR system)
Go to Step 18. (without EGR system)
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No
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Replace the malfunctioning parts.
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17
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Inspect the EGR system.
Is the EGR system normal?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning part, according to inspection result.
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18
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Inspect the variable valve timing control system operation.
Does the variable valve timing control system function properly?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning parts.
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19
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Is the engine compression correct?
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Yes
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Inspect the following:
• Valve timing.
• Internal transaxle components (ATX)
• Clutch (MTX)
• Brake system for dragging
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No
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Inspect for the cause.
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20
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Verify the test results.
• If normal, return to the diagnostic index to service any additional symptoms.
• If the malfunction remains, inspect related Service information and perform repair or diagnosis.
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