NO.13 KNOCKING/PINGING-ACCELERATION/CRUISE [MZI-3.7]

id0103d2812100

13 | KNOCKING/PINGING—ACCELERATION/CRUISE
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DESCRIPTION | • Sound is heard when air/fuel mixture is ignited by something other than spark plug (such as hot spot in combustion chamber).
POSSIBLE CAUSE | • Engine overheating due to cooling system malfunction • IAT sensor malfunction • MAF sensor malfunction • PCM DTC is stored. • Inadequate engine compression • Erratic signal from CMP sensor • Erratic signal from CKP sensor • Inadequate fuel pressure ― Intermittent open or short circuit in fuel pump circuit ― Fuel pump mechanical malfunction ― Fuel line restriction or clogging ― Pressure regulator malfunction (built-in fuel pump unit) • KS malfunction • Improper ignition timing • Poor fuel quality (i.e. Fuel RON is not specified, excessive cleaning agents added in fuel.) 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 | Caution • While performing this step, always operate the vehicle in a safe and lawful manner. • When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later. Access the PCM PID ECT using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZI-3.7].) Verify the ECT PID is less than 116 °C {241 °F} during the driving. Is the ECT PID less than the specification? | Yes | Go to the next step.
No | Inspect the cooling system for cause of overheating. Repair or replace the malfunctioning part according to the inspection results.
2 | Access and monitor the following PCM PIDs using the M-MDS: (See ON-BOARD DIAGNOSTIC TEST [MZI-3.7].) • IAT • MAF Are all PIDs normal? (See PCM INSPECTION [MZI-3.7].) | Yes | Go to the next step.
No | IAT PID is not normal: • Inspect the IAT sensor. (See INTAKE AIR TEMPERATURE (IAT) SENSOR INSPECTION [MZI-3.7].) MAF PID is not normal: • Inspect the MAF sensor. (See MASS AIR FLOW (MAF) SENSOR INSPECTION [MZI-3.7].) Repair or replace the malfunctioning part according to the inspection results.
3 | 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.
4 | Is the engine compression correct? | Yes | Go to the next step.
No | Inspect for cause. Repair or replace the malfunctioning part according to the inspection results.
5 | 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.
6 | 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.
7 | Install the fuel pressure gauge between fuel pipe and fuel distributor. Start the engine and run it at idle. Measure the fuel line pressure during idle. (See FUEL LINE PRESSURE INSPECTION [MZI-3.7].) Is the fuel line pressure correct during idle? | 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].)
8 | Inspect the KS. (See KNOCK SENSOR (KS) INSPECTION [MZI-3.7].) Is the KS normal? | Yes | Go to the next step.
No | Replace the KS. (See KNOCK SENSOR (KS) REMOVAL/INSTALLATION [MZI-3.7].)
9 | Inspect the ignition timing. (See ENGINE TUNE-UP [MZI-3.7].) Is the ignition timing properly? | Yes | Replace the fuel.
No | Repair or replace the malfunctioning part according to the inspection results.
10 | • 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].)