NO.4 HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK [MZI-3.7]

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4 | HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK
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DESCRIPTION | • Starter cranks engine at normal speed but engine requires excessive cranking time before starting. • Battery is in normal condition.
POSSIBLE CAUSE | • Vacuum leakage • Poor fuel quality • Air leakage or restriction in intake-air system • Low or dead battery • Charging system malfunction • PCM DTC is stored. • Engine overheating • Purge solenoid valve malfunction • MAF sensor contamination • Incorrect MAF sensor ground voltage • Improper operation of drive-by-wire control system • Restriction in exhaust system • Open circuit in PCM ground circuit • Ignition coil related circuit malfunction • Erratic signal to ignition coil • Spark plug malfunction • Erratic signal from CKP sensor • Erratic signal from CMP sensor • Inadequate fuel pressure ― Open or short circuit in fuel pump and related wiring harness ― Fuel pump mechanical malfunction ― Fuel line clogged ― Pressure regulator malfunction (built-in fuel pump unit) • Fuel leakage from fuel system • PCV valve malfunction • Starting system malfunction • Electrical connector loose or terminal poor contact Warning • The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before servicing the fuel system: ― Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. ― Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete “BEFORE SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual. (See BEFORE SERVICE PRECAUTION [MZI-3.7].)(See AFTER SERVICE PRECAUTION [MZI-3.7].) Caution • Disconnecting/connecting quick release connector without cleaning it may cause damage to fuel pipe and quick release connector. Always clean quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Inspect for the following: • Vacuum leakage • Proper fuel quality (such as proper octane, contamination, winter/summer blend) • Loose bands on intake-air system • Cracks on intake-air system parts • Intake-air system restriction (such as air cleaner element, fresh air duct) Are all items normal? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part according to the inspection results. Repeat Step 1.
2 | Turn the ignition switch to the ON position (Engine off). Retrieve any PCM DTCs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZI-3.7].) Are there any DTCs displayed? | Yes | DTC is displayed: • Go to the appropriate DTC inspection. (See DTC TABLE [MZI-3.7].)
No | No DTC is displayed: • Go to the next step.
3 | Is the engine overheating? | Yes | Go to the symptom troubleshooting “NO.17 COOLING SYSTEM CONCERNS-OVERHEATING”. (See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZI-3.7].)
No | Go to the next step.
4 | Disconnect a vacuum hose from purge solenoid valve and plug opening end of vacuum hose. Start the engine. Is the starting condition improved? | Yes | Inspect if the purge solenoid valve is stuck open. Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
5 | Inspect the MAF sensor for following: • Contamination • MAF sensor terminal B voltage (ground circuit) Is there any malfunction? | Yes | Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
6 | Attempt to start the engine at part throttle. Does the engine run smoothly at part throttle? | Yes | Inspect the drive-by-wire control system operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7].) Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
7 | Visually inspect the exhaust system part. Is there any deformed exhaust system part? | Yes | Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
8 | Verify the PCM ground point condition. Is there any ground point looseness or lifting in the PCM. | Yes | Repair the ground point looseness and lifting.
No | Go to the next step.
9 | Inspect the ignition coil related wiring harness condition (intermittent open or short circuit) for all cylinders. Are wiring harness conditions normal? | Yes | Go to the next step.
No | Repair or replace suspected wiring harness and connector.
10 | Perform the spark test. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7].) Is a strong blue spark visible at each cylinder? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part according to the inspection results.
11 | Verify the spark plug conditions when the spark plug removed in Step 10. Is the spark plug wet, covered with carbon or grayish white? | Yes | Spark plug is wet or covered with carbon: • Inspect for fuel leakage from fuel injector. Spark plug is grayish white: • Inspect the fuel injector for clogging. Repair or replace the malfunctioning part according to the inspection results.
No | Install the spark plugs on original cylinders. Go to the next step.
12 | Inspect the CKP sensor. (See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [MZI-3.7].) Is the CKP sensor normal? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part according to the inspection results.
13 | Inspect the CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR INSPECTION [MZI-3.7].) Is the CMP sensor normal? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part according to the inspection results.
14 | Inspect the fuel line pressure. (See FUEL LINE PRESSURE INSPECTION [MZI-3.7].) Is the fuel line pressure correct? | Yes | Go to the next step.
No | Zero or low: • Inspect the following: ― Fuel pump relay ― Fuel pump circuit ― Fuel line for clogging • If there is no malfunction, replace the fuel pump unit. (Fuel pump or pressure regulator malfunction) (See FUEL PUMP UNIT REMOVAL/INSTALLATION [MZI-3.7].) High: • Replace the fuel pump unit. (Pressure regulator malfunction) (See FUEL PUMP UNIT REMOVAL/INSTALLATION [MZI-3.7].)
15 | Visually inspect for fuel leakage at fuel injector, O-ring, and fuel line. Is there any fuel leakage? | Yes | Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
16 | Note • The PCV valve cannot be reassembled once it is removed because the tabs will have bee n broken. Inspect the PCV valve without removing it from the vehicle. Inspect the PCV valve with it installed. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [MZI-3.7].) Is the PCV valve normal? | Yes | Go to the next step.
No | Replace the PCV valve. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [MZI-3.7].)
17 | Inspect the starting system. (See STARTER INSPECTION [MZI-3.7].) Is the starting system normal? | Yes | Inspect for loose connectors or poor terminal contact.
No | Repair or replace the malfunctioning part according to the inspection results.
18 | • Verify test results. ― If normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZI-3.7].) ― If malfunction remains, inspect related Service Information and perform repair or diagnosis. • If vehicle is repaired, troubleshooting completed. • If vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZI-3.7].)