Inspection Procedure

HINT: 

• In contrast to normal malfunction diagnosis for components, circuits and systems, DTCs P1603 and P1605 are used to determine the malfunctioning area from the problem symptoms and freeze frame data when the user mentions problems such as engine stall.

  As these DTCs can be stored as a result of certain user actions, even if these DTCs are output, if the customer makes no mention of problems, clear these DTCs without performing any troubleshooting and return the vehicle to the customer.

• If any other DTCs are output, perform troubleshooting for those DTCs first.
• Use any information from the customer problem analysis about the condition of the vehicle at the time when the problem occurred (how the engine stopped, conditions when the engine was restarted, etc.) as a reference.

  Symptom	Suspected Area
  Engine vibration occurs and engine stops	Air-fuel ratio abnormal
  Engine stops with no engine vibration	Ignition system, injection stoppage, high load from external parts
  Engine can be started with accelerator pedal depressed	Insufficient air volume
  Rough idling after engine started	Air-fuel ratio abnormal, abnormal combustion

• Read freeze frame data using the Techstream. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.
• When confirming the freeze frame data, be sure to check all 5 sets of freeze frame data. Refer to FREEZE FRAME DATA .
• When DTC P1603 (Engine Stall History) is stored, DTC P1605 (Rough Idling) is also stored. When confirming freeze frame data, check DTC P1605. (The ECM stores DTC P1605 first. Therefore, the 5 sets of freeze frame data can be confirmed through DTC P1605, enabling the technician to obtain more information.)
• When confirming freeze frame data, if there are multiple items related to the cause of the malfunction, perform troubleshooting for all related items.
• Try to operate the vehicle under the conditions recorded in the freeze frame data which were present when the malfunction occurred. Confirm the data at this time and the data when the engine is idling (engine warmed up, no load, and shift lever in P or N) and compare these data with the freeze frame data.
• Inspections take into account the fact that the malfunction may not have reoccurred and place emphasis on checking the vehicle conditions present at the time when the malfunction occurred.
• When performing inspections, jiggle the relevant wire harnesses and connectors in an attempt to reproduce malfunctions that do not always occur.

Inspection flow

Using freeze frame data, narrow down the parts to be inspected according to the vehicle conditions at the time when the malfunction occurred.

P1603: 

1: 

• If the engine stalled when the intake air volume was low (during idling or deceleration), there may be a decrease in torque due to an incorrect air-fuel ratio, etc.
• If the engine stalled when the intake air volume was high (during driving or acceleration), there may be a major malfunction such as continuous misfire due to ignition stoppage, fuel injection stoppage, etc. and the torque drops to zero.

2: 

• If the engine speed decreased slowly, there may have been a decrease in torque due to an air-fuel ratio that was incorrect (by approximately 20 to 30%), etc.
• If the engine speed decreased rapidly, there may have been a malfunction such as when the engine misfires almost continuously due to ignition stoppage, fuel injection stoppage, etc., or when the external load increases due to an external part malfunctioning.

3: 

• If the air-fuel ratio is abnormal, there may have been an intake air leak, sensor malfunction, or fuel supply problem.
• If the vehicle was normal, the air volume may have been insufficient, or the ignition timing may have been incorrect.

P1603 inspection flow: Narrow down the parts to be inspected according to the vehicle conditions at the time when the malfunction occurred (freeze frame data).

Vehicle State	Engine Speed	Suspected Area		Primary Parts to Inspect	Procedure
Idling or decelerating	Slowly decreases and engine stalls	Air-fuel ratio abnormal	Air suction	Intake system connections Purge VSV system Brake booster	3 to 6
			Sensor malfunction (value from sensor too lean)	Mass air flow meter Engine coolant temperature sensor Thermostat Air fuel ratio sensor system	7 to 16
			Sensor malfunction (value from sensor too rich)		25 to 34
			Fuel supply problem	Fuel pump control system Purge VSV system Fuel line ECM	17 to 24
		Intake air volume insufficient	ISC flow rate	Throttle body assembly (ISC valve)	35 to 37
			Excessive valve overlap	Camshaft timing oil control valve VVT system	38, 39
		Ignition timing incorrect	Does not operate as expected	Engine coolant temperature sensor Mass air flow meter	41, 42
	Rapidly decreases and engine stalls	Ignition and injection stops (electrical system malfunction)	Power temporarily cut	Power supply circuit (Fuel injector assembly, Ignition coil assembly)	43 to 46
		External part malfunctioning	Increase in load	Air conditioning system Electrical load signal system Power steering system A/T system Park/neutral position switch	47 to 49
Accelerating	-	Crankshaft position sensor, VVT sensor malfunction	Power temporarily cut	Check DTCs	1
		Mass air flow meter	Foreign matter adhesion	Mass air flow meter	50, 51
		Fuel supply problem	Fuel leak, clog	Fuel pump control system Fuel line	54 to 56
		Ignition and injection stops (electrical system malfunction)	Power temporarily cut	Power supply circuit (Fuel injector, Ignition coil assembly)	52, 53

P1605: 

1: 

• If the engine speed decreased slowly, there may have been a decrease in torque due to an air-fuel ratio that was incorrect (by approximately 20 to 30%), etc.
• If the engine speed decreased rapidly, there may have been a malfunction such as when the engine misfires almost continuously due to ignition stoppage, fuel injection stoppage, etc., or when the external load increases due to an external part malfunctioning.

2: 

• If the air-fuel ratio is abnormal, there may have been an intake air leak, sensor malfunction, or fuel supply problem.
• If the vehicle was normal, the air volume may have been insufficient, or the ignition timing may have been incorrect.

P1605 inspection flow: Narrow down the parts to be inspected according to the vehicle conditions at the time when the malfunction occurred (freeze frame data).

Engine Speed	Suspected Area		Primary Parts to Inspect	Procedure
Slowly decreases and engine stalls	Air-fuel ratio abnormal	Air suction	Intake system connections Purge VSV system Brake booster	3 to 6
		Sensor malfunction (value from sensor too lean)	Mass air flow meter Engine coolant temperature sensor Thermostat Air fuel ratio sensor system	7 to 16
		Sensor malfunction (value from sensor too rich)		25 to 34
		Fuel supply problem	Fuel pump control system Purge VSV system Fuel line ECM	17 to 24
	Intake air volume insufficient	ISC flow rate	Throttle body assembly (ISC valve)	35 to 37
	Ignition timing incorrect	Does not operate as expected	Knock sensor Engine coolant temperature sensor Mass air flow meter	40 to 42
Rapidly decreases and engine stalls	Ignition and injection stops (electrical system malfunction)	Power temporarily cut	Power supply circuit (Fuel injector assembly, Ignition coil assembly)	43 to 46
	External part malfunctioning	Increase in load	Air conditioning system Electrical load signal system Power steering system A/T system Park/neutral position switch	47 to 49