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NO.4 HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK [WITH WU-TWC]

id0103008010c5

4 | HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK
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DESCRIPTION | • The starter cranks the engine at normal speed but the engine requires excessive cranking time before starting. • The battery is in normal condition.
POSSIBLE CAUSE | • Erratic signal to ignition coil • Vacuum leakage • Poor fuel quality • Starting system malfunction • Spark plug malfunction • Air leakage from intake-air system • Erratic signal from CKP sensor • Erratic signal from CMP sensor • Improper air/fuel mixture ratio control • Air cleaner restriction • IAC valve malfunction • PCV valve malfunction • Inadequate fuel pressure • Purge solenoid valve malfunction • MAF sensor contamination • Restriction in exhaust system • EGR system malfunction (ZJ) • Pressure regulator malfunction Warning The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before performing the fuel system services: • 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 the "BEFORE REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual. Caution • If there is foreign material on the connecting area of the quick release connector, it might damage the connector or the fuel pipe. To prevent this, disconnect the connector and clean the connecting area before connecting.

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Inspect the following: • Vacuum leakage • Proper fuel quality (e.g. proper octane, contamination, winter/summer blend) • Loose bands on the intake-air system • Cracks on the intake-air system parts • Air cleaner restriction Are all items normal? | Yes | Go to the next step.
No | Service if necessary. Repeat Step 1.
2 | Connect the WDS or equivalent to the DLC-2. Retrieve any KOEO and KOER DTCs. (See KOEO/KOER SELF-TEST.) Are any KOEO or KOER DTCs displayed? | Yes | DTC is displayed: Go to the appropriate DTC test.
No | No DTC is displayed: Go to the next step.
3 | Is the engine overheating? | Yes | Go to symptom troubleshooting "No.17 Cooling system concerns - Overheating".
No | Go to the next step.
4 | Inspect the ignition coil related wiring harness conditions (intermittent open or short circuit) for all cylinders. Are wiring harness conditions normal? | Yes | Go to the next step.
No | Repair the suspected wiring harnesses.
5 | Inspect the spark plugs. 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 the fuel injector. Spark plug is grayish white: Inspect for a clogged fuel injector.
No | Install spark plugs on original cylinders. Go to the next step.
6 | Visually inspect the CKP sensor and the teeth of the crankshaft pulley. Are the CKP sensor and the teeth of the crankshaft pulley normal? | Yes | Go to the next step.
No | Replace the malfunctioning parts.
7 | 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? | Yes | Go to the next step.
No | Replace the plate.
8 | Remove and shake the PCV valve. Does the PCV valve rattle? | Yes | Go to the next step.
No | Replace PCV valve.
9 | Install a fuel pressure gauge between fuel pipe and the fuel distributor. Connect on the WDS or equivalent to the DLC-2. Turn on the fuel pump using the FP PID in output state control of the datalogger function. Is the fuel line pressure correct? | Yes | Go to the next step.
No | Zero or low: Inspect the fuel pump relay and the fuel pump unit related circuits. Inspect for fuel leakage inside the pressure regulator. Inspect for a clogged main fuel line. High: Inspect the pressure regulator for the cause of high pressure. Inspect for a clogged fuel return line. Inspect the vacuum hose to the pressure regulator.
10 | Is the fuel line pressure held after FP PID is turned off? | Yes | Go to the next step.
No | Inspect the pressure regulator diaphragm. • If the condition is normal, inspect the fuel injector. • If the condition is not normal, replace the pressure regulator.
11 | Disconnect the vacuum hose from the pressure regulator and the plug hose. Start the engine. Does the fuel line pressure remain within ±20 kPa {±0.21 kgf/cm 2, ±3 psi} while driving vehicle? | Yes | Go to the next step.
No | Inspect for a clogged fuel filter.
12 | Connect the vacuum hose to the pressure regulator. Install a vacuum gauge to the intake manifold. Start the engine. Does the fuel pressure gauge reading increase as the vacuum gauge reading decreases and/or the fuel pressure gauge reading decrease as the vacuum gauge reading increase? | Yes | Go to the next step.
No | Connect a vacuum pump to the pressure regulator. Start the engine. Verify that the fuel pressure gauge reading changes as the vacuum changes. • If it changes, inspect the vacuum line. • If it does not change, replace the pressure regulator.
13 | Disconnect the vacuum hose from the purge solenoid valve and plug the open end of the vacuum hose. Attempt to start the engine. Is the starting condition improved? | Yes | Inspect if the purge solenoid valve sticks open.
No | Go to the next step.
14 | Inspect the MAF sensor for contamination. Is there any contamination? | Yes | Replace the MAF sensor.
No | Go to the next step.
15 | Visually inspect the exhaust system part. Is there any deformed exhaust system part? | Yes | Replace the malfunction part.
No | Go to the next step. (with EGR system) Go to Step 17. (without EGR system)
16 | Inspect the engine condition while tapping the EGR valve housing. Does the engine condition improve? | Yes | Replace the EGR valve. (See EGR VALVE REMOVAL/INSTALLATION [WITH WU-TWC].)
No | Go to the next step.
17 | Inspect the starting system. Is the starting system normal? | Yes | Inspect for loose connectors or poor terminal contact. • If normal, remove the EGR valve and visually inspect for a mechanically stuck EGR valve.
No | Repair or replace components if necessary.
18 | 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. - If the vehicle is repaired, the troubleshooting is completed. - If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM.