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Diagnostic Procedure

NO. 29 SPARK PLUG CONDITION DIAGNOSTIC PROCEDURE

STEP INSPECTION RESULTS ACTION
1 VERIFY SPARK PLUG CONDITION
 Yes Specific plug is wet or covered with carbon:
  • Go to the next step.

Specific plug looks grayish white:
  • Go to Step 7.

All plugs are wet or covered with carbon:
  • Go to Step 9.

All plugs look grayish white:
  • Go to Step 15.
No Symptom troubleshooting completed.
2 DETERMINE IF MALFUNCTION CAUSE IS ENGINE OIL LOSS OR OTHER
  • Are the spark plugs wet/covered with carbon from the engine oil?
 Yes Inspect all areas related to oil, working up and down.
Repair or replace the malfunctioning part according to the inspection results.
No Go to the next step.
3 INSPECT SPARK PLUG
  • Inspect the spark plugs for the following:
  • Air gap
  • Cracked insulator
  • Heat range
    • Worn electrode
  • Is there any malfunction?
 Yes Replace the spark plug.
(See SPARK PLUG REMOVAL/INSTALLATION .)
No Go to the next step.
4 INSPECT ENGINE COMPRESSION
  • Inspect the compression pressure at the suspected cylinder. (See COMPRESSION INSPECTION .)
  • Is there any malfunction?
 Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to the next step.
5 INSPECT IGNITION SYSTEM OPERATION
 Yes Go to the next step.
No Repair or replace the malfunctioning part according to the inspection results.
6 INSPECT FUEL LINE PRESSURE
 Yes Zero or low:
  • Inspect the fuel pump relay and the fuel pump circuit. (See RELAY INSPECTION .)
  • Inspect the fuel line for restriction.
  • If there is any malfunction:
    • Repair or replace the malfunctioning part according to the inspection results.
  • If there is no malfunction:

High:
No Inspect the fuel injector for the following:
  • Injection volume
  • Leakage
  • Open or short circuit in injector

Repair or replace the malfunctioning part according to the inspection results.
7 INSPECT SPARK PLUG
  • Inspect the spark plug for the following:
  • Air gap
    • Heat range
  • Is there any malfunction?
 Yes Replace the spark plug.
(See SPARK PLUG REMOVAL/INSTALLATION .)
No Go to the next step.
8 INSPECT FUEL INJECTOR OPERATION
 Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to the next step.
9 INSPECT AIR CLEANER ELEMENT
  • Is the air cleaner element clean?
 Yes Go to the next step.
No Replace the air cleaner element.
10 INSPECT IGNITION SYSTEM OPERATION
 Yes Go to the next step.
No Repair or replace the malfunctioning part according to the inspection results.
11 INSPECT FUEL LINE PRESSURE
 Yes Zero or low:
  • Inspect the fuel pump relay and the fuel pump circuit. (See RELAY INSPECTION .)
  • Inspect the fuel line for restriction.
  • If there is any malfunction:
    • Repair or replace the malfunctioning part according to the inspection results.
  • If there is no malfunction:

High:
No Go to the next step.
12 VERIFY CURRENT INPUT SIGNAL STATUS
  • ECT
  • MAF
  • O2S11 (When engine can be started)
    • O2S12 (When engine can be started)
 Yes Go to the next step.
No ECT PID is not as specified:

MAF PID is not as specified:

O2S11 PID is not as specified:

O2S12 PID is not as specified:

Repair or replace the malfunctioning part according to the inspection results.
13 INSPECT PURGE CONTROL SYSTEM OPERATION
 Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to the next step.
14 INSPECT ENGINE COMPRESSION
 Yes Repair or replace the malfunctioning part according to the inspection results.
No Visually inspect for deformed exhaust system parts.
Repair or replace the malfunctioning part according to the inspection results.
15 INSPECT INTAKE-AIR SYSTEM FOR AIR SUCTION
  • If the engine cannot be started:
    • Inspect the intake air system for air leakage.
  • If the engine can be started:
  • Is the air sucked in from intake air system?
 Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to the next step.
16 INSPECT FUEL LINE PRESSURE
 Yes Zero or low:
  • Inspect the fuel pump relay and the fuel pump circuit. (See RELAY INSPECTION .)
  • Inspect the fuel line for restriction.
  • If there is any malfunction:
    • Repair or replace the malfunctioning part according to the inspection results.
  • If there is no malfunction:

High:
No Go to the next step.
17 VERIFY CURRENT INPUT SIGNAL STATUS
  • ECT
  • MAF
  • O2S11 (When engine can be started)
    • O2S12 (When engine can be started)
 Yes Inspect the PCM ground condition.
Repair or replace the malfunctioning part according to the inspection results.
No Repair or replace the malfunctioning part according to the inspection results.
18 Verify test results.
  • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX .)
  • If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.
  • If the vehicle is repaired, troubleshooting is completed.
    • If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.
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