NO.27 SPARK PLUG CONDITION


27	SPARK PLUG CONDITION
DESCRIPTION	Incorrect spark plug condition
POSSIBLE CAUSE	Note • Inspecting the spark plugs condition can determine whether the problem is related to a specific spark plug or possibly all spark plugs. Wet/carbon stuck on specific plug: • Spark-Weak, not visible • Air/fuel mixture-Excessive fuel injection volume • Compression-No compression, low compression • Faulty spark plug Grayish white with specific plug: • Air/fuel mixture-Insufficient fuel injection volume • Faulty spark plug Wet/carbon is stuck on all plugs: • Spark-Spark weak • Air/fuel mixture-Too rich • Compression-Low compression • Clogging in intake/exhaust system Grayish white with all plugs: • Air/fuel mixture-Too lean Warning The following troubleshooting flow chart contains 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 REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual. (See BEFORE REPAIR PROCEDURE.) (See AFTER REPAIR PROCEDURE.) Caution • Disconnecting/connecting quick release connector without cleaning it may possibly 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.


STEP	INSPECTION	RESULTS	ACTION
1	Remove all the spark plugs. Inspect the spark plug condition. Is the spark plug condition normal?	Yes	Troubleshooting completed.
1		No	Specific plug is wet or covered with carbon: Go to the next step. Specific plug looks grayish white: Go to Step 8. All plugs are wet or covered with carbon: Go to Step 10. All plugs look grayish white: Go to Step 17.
2	Is the spark plug wet/covered with carbon by engine oil?	Yes	Working up and down inspect all the areas related to the oil.
2	Is the spark plug wet/covered with carbon by engine oil?	No	Go to the next step.
3	Inspect the spark plug for the following: • Cracked insulator • Heat range • Air gap • Worn electrode Is the spark plug normal?	Yes	Go to the next step.
3		No	Replace the spark plug.
4	Inspect the engine compression. (See COMPRESSION INSPECTION.) Is it normal?	Yes	Go to Step 10.
4		No	Go to the next step.
5	Perform the metering oil pump control inspection. (See Metering Oil Pump Control Inspection.) Does the metering oil pump control operate properly?	Yes	Go to the next step.
5		No	Repair or replace the malfunctioning part according to the inspection results. After that overhaul or replace the engine. (See Engine Workshop Manual.)
6	Check the engine oil condition. Is the engine oil low viscosity and/or is there a gasoline odor?	Yes	Replace engine oil. Inspect the ECT sensor and the related wiring harnesses. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION.) After that overhaul or replace the engine. (See Engine Workshop Manual.)
6		No	Go to the next step.
7	Inspect the oil pressure. (See OIL PRESSURE INSPECTION.) Is the oil pressure within the specification?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning part according to the inspection results. After that overhaul or replace the engine. (See Engine Workshop Manual.)
8	Turn the ignition switch off. Disconnect the fuel line quick release connector and install the fuel gauge to the fuel line. Start the engine and run it at idle. Measure the fuel line pressure at idle. Is the fuel line pressure correct at idle? (See FUEL LINE PRESSURE INSPECTION.)	Yes	Go to the next step.
8		No	Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.) After that overhaul or replace the engine. (See Engine Workshop Manual.)
9	Check the oil pipe between the metering oil pump and the metering oil nozzle. Is there any air and/or clogging in the oil pipe?	Yes	Inspect and repair for leakage and/or clogging in the oil passage at engine. After that overhaul or replace the engine. (See Engine Workshop Manual.)
9		No	Overhaul or replace the engine. (See Engine Workshop Manual.)
10	Install all the spark plugs. Perform the spark test at the suspected faulty rotor. Is a strong blue spark visible? (Compare with normal rotor.)	Yes	Go to the next step.
10		No	Repair or replace the malfunctioning parts.
11	Perform the fuel pump control system inspection. (See Fuel Pump Control System Inspection.) Does the fuel pump control system operate properly?	Yes	Go to the next step.
11		No	Repair or replace the malfunctioning part according to the fuel pump control system inspection results.
12	Install the fuel pressure gauge to the fuel line quick release connector. Short the check connector terminal F/P to the body GND using a jumper wire. Turn the ignition switch to the ON position (Engine off). Is the fuel line pressure correct with the ignition switch at ON? (See FUEL LINE PRESSURE INSPECTION.)	Yes	Inspect the fuel injector for the following: • Open or short in injector • Leakage • Injection volume (See FUEL INJECTOR INSPECTION.)
12		No	Zero or low: Inspect for clogged fuel line. If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.)
13	Inspect the spark plug for the following. • Heat range • Air gap Is the spark plug normal?	Yes	Go to the next step.
13		No	Replace the spark plug.
14	Remove the suspected fuel injector. Inspect the following: • Resistance (See FUEL INJECTOR INSPECTION.) • Fuel injection volume (See FUEL INJECTOR INSPECTION.) Are all the above items normal?	Yes	Inspect for an open circuit between the suspected fuel injector connector terminal and the PCM connector at the following terminals: Front rotor: • For FP1: 2M • *For FP2: 3A • For FS: 2G Rear rotor: • For RP1: 2J • For RP2: 3D* • For RS: 2D
14		No	Replace the fuel injector. FUEL INJECTOR REMOVAL/INSTALLATION.)
15	Is the air cleaner element free of restrictions?	Yes	Go to the next step.
15	Is the air cleaner element free of restrictions?	No	Replace the air cleaner element.
16	Perform the spark test. Is a strong blue spark visible at each spark plug?	Yes	Go to the next step.
16		No	Repair or replace the malfunctioning parts.
17	Perform the fuel pump control system inspection. (See Fuel Pump Control System Inspection.) Does the fuel pump control system operate properly?	Yes	Go to the next step.
17		No	Repair or replace the malfunctioning part according to the fuel pump control system inspection results.
18	Install the fuel pressure gauge to the fuel line quick release connector. Short the check connector terminal F/P to the body GND using a jumper wire. Turn the ignition switch to the ON position (Engine off). Is the fuel line pressure correct with the ignition switch at ON? (See FUEL LINE PRESSURE INSPECTION.)	Yes	Go to the next step.
18		No	Zero or low: Inspect for clogged fuel line. If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.)
19	Inspect the following PIDs: • ECT • O2S11 (When the engine can be started.) • O2S12 (When the engine can be started.) • MAF (See PCM INSPECTION.) Are the PIDs normal?	Yes	Go to the next step.
19		No	Repair or replace the malfunctioning parts.
20	Perform the purge control inspection. (When engine can be started) (See Purge Control System Inspection.) Is the purge control correct?	Yes	Go to the next step.
20		No	Repair or replace the malfunctioning parts.
21	Inspect the engine compression. (See COMPRESSION INSPECTION.) Is it normal?	Yes	Go to Step 26.
21		No	Go to the next step.
22	Perform the metering oil pump control inspection. (See Metering Oil Pump Control Inspection.) Does the metering oil pump control operate properly?	Yes	Go to the next step.
22		No	Repair or replace the malfunctioning part according to the inspection results. After that overhaul or replace the engine. (See Engine Workshop Manual.)
23	Check the engine oil condition. Is the engine oil low viscosity and/or is there a gasoline odor?	Yes	Replace the engine oil. Inspect the ECT sensor and the related wiring harnesses. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION.) After that overhaul or replace the engine. (See Engine Workshop Manual.)
23		No	Go to the next step.
24	Inspect the oil pressure. (See OIL PRESSURE INSPECTION.) Is the oil pressure within the specification?	Yes	Go to the next step.
24		No	Repair or replace the malfunctioning part according to the inspection results. After that overhaul or replace the engine. (See Engine Workshop Manual.)
25	Turn the ignition switch off. Disconnect the fuel line quick release connector and install the fuel gauge to the fuel line. Start the engine and run it at idle. Measure the fuel line pressure at idle. Is the fuel line pressure correct at idle? (See FUEL LINE PRESSURE INSPECTION.)	Yes	Go to the next step.
25		No	Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.) After that overhaul or replace the engine. (See Engine Workshop Manual.)
26	Check the oil pipe between the metering oil pump and the metering oil nozzle. Is there any air and/or clogging in the oil pipe?	Yes	Inspect and repair for leakage and/or clogging in the oil passage at the engine. After that overhaul or replace the engine. (See Engine Workshop Manual.)
26		No	Overhaul or replace the engine. (See Engine Workshop Manual.)
27	When the engine cannot be started, inspect the intake-air system for air leakage. When the engine can be started, perform the intake manifold vacuum inspection. Is air sucked from the intake-air system?	Yes	Repair or replace the malfunctioning part.
27		No	Go to the next step.
28	Perform the fuel pump control system inspection. (See Fuel Pump Control System Inspection.) Does the fuel pump control system operate properly?	Yes	Go to the next step.
28		No	Repair or replace the malfunctioning part according to the fuel pump control system inspection results.
29	Install the fuel pressure gauge to the fuel line quick release connector. Short the check connector terminal F/P to the body GND using a jumper wire. Turn the ignition switch to the ON position (Engine off). Is the fuel line pressure correct with the ignition switch at ON? (See FUEL LINE PRESSURE INSPECTION.)	Yes	Inspect the following PIDs: • ECT • O2S11 • O2S12 • MAF (See PCM INSPECTION.) Inspect the PCM GND condition.
29		No	Zero or low: Inspect for clogged fuel line. If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.)
30	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. • If the malfunction remains, inspect the related Service Information and perform the repair or diagnosis.