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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 336 (Symptom Troubleshooting (Engine Control System AJ)) >> No. 29 Spark Plug Condition >> Diagnostic procedure

Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.
NO. 29 SPARK PLUG CONDITION [AJ] DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1
  • Remove all spark plugs.
  • Inspect spark plug condition.
  • Is spark plug condition okay?
 Yes Troubleshooting completed.
No 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.
2
  • Is spark plug wet/covered with carbon by engine oil?
 Yes Working up and down inspect all areas related to oil.
No Go to the next step.
3
  • Inspect spark plug for the following:
    • Cracked insulator
    • Heat range
    • Air gap
    • Worn electrode
  • Is spark plug okay?
 Yes Go to the next step.
No Replace spark plug.
4
  • Inspect compression pressure at suspected faulty cylinder.
  • Is engine compression correct?

    (See COMPRESSION INSPECTION .)

 Yes Go to the next step.
No Repair or replace malfunctioning part.
5
  • Install all spark plugs.
  • Perform spark test at suspected faulty cylinder.
  • Is strong blue spark visible? (Compare with normal cylinder.)
 Yes Go to the next step.
No Repair or replace malfunctioning parts.
6
  • Install fuel pressure gauge between fuel filter and fuel distributor.
  • Short check connector terminal F/P to body GND using a jumper wire. (See AFTER REPAIR PROCEDURE .)
  • Turn ignition switch to ON position (Engine OFF).
  • Inspect fuel line pressure.

    (See FUEL LINE PRESSURE INSPECTION .)

  • Is fuel line pressure correct with ignition switch at ON position?
 Yes Inspect fuel injector for the following:
  • Open or short in injector
  • Leakage
  • Injection volume
No Zero or low: 

High: 
7
  • Inspect spark plug for the following:
    • Heat range
    • Air gap
  • Is spark plug okay?
 Yes Go to the next step.
No Replace spark plug.
(See SPARK PLUG INSPECTION .)
8 Yes Inspect for open circuit between suspected fuel injector terminals and PCM at the following terminals:
  • For #1 cylinder:  76
  • For #2 cylinder:  50
  • For #3 cylinder:  75
  • For #4 cylinder:  49
  • For #5 cylinder:  74
  • For #6 cylinder:  48
No Replace fuel injector.
(See FUEL INJECTOR REMOVAL/INSTALLATION [AJ] .)
9
  • Is air cleaner element free of restriction?
 Yes Go to the next step.
No Replace air cleaner element.
10
  • Perform spark test.
  • Is strong blue spark visible at each cylinder?
 Yes Go to the next step.
No Repair or replace malfunctioning part.
11
  • Install fuel pressure gauge between fuel filter and fuel distributor.
  • Short check connector terminal F/P to body GND using a jumper wire. (See AFTER REPAIR PROCEDURE .)
  • Turn ignition switch to ON position (Engine OFF).
  • Is fuel line pressure correct with ignition switch at ON position.

    (See FUEL LINE PRESSURE INSPECTION .)

 Yes Go to the next step.
No Zero or low: 

High: 
12
  • Inspect the following PIDs:
  • Are PIDs okay?
 Yes Go to the next step.
No Repair or replace malfunctioning part.
13
  • Perform purge control inspection (when engine can be started).
  • Is purge control correct?
 Yes Go to the next step.
No Repair or replace malfunctioning part.
14 Yes Inspect for clogging in exhaust system.
No Repair or replace malfunctioning part.
15
  • When engine cannot be started, inspect intake-air system for air leakage.
  • When engine can be started, perform intake manifold vacuum inspection.
  • Is air sucked in from intake-air system?
 Yes Repair or replace malfunctioning part.
No Go to the next step.
16
  • Install fuel pressure gauge between fuel filter and fuel distributor.
  • Short check connector terminal F/P to body GND using a jumper wire.

    (See AFTER REPAIR PROCEDURE .)

  • Turn ignition switch to ON position (Engine OFF).
  • Is fuel line pressure correct with ignition switch at ON position?

    (See FUEL LINE PRESSURE INSPECTION .)

 Yes Inspect the following PIDs:
  • ECT
  • O2S11
  • O2S21
  • MAF
  • O2S12
  • O2S22

    (See PCM INSPECTION .) Inspect PCM GND condition.
No Zero or low: 

High: 
17
  • Verify test results.
    • If okay, return to diagnostic index to service any additional symptoms.
    • If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.
      • If vehicle is repaired, troubleshooting completed.
      • If vehicle is not repaired or additional diagnostic information is not available, reprogram PCM if later calibration is available. Retest.
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