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2008 - MX-5 - Engine

NO.19 EXHAUST SMOKE [LF]



19

EXHAUST SMOKE

DESCRIPTION

Blue, black, or white smoke from exhaust system

POSSIBLE CAUSE

Blue smoke (Burning oil):

  • PCV valve malfunction

  • Engine internal oil leakage

White smoke (Water in combustion):

  • Cooling system malfunction (coolant loss)

  • Engine internal coolant leakage

Black smoke (Rich fuel mixture):

  • Air cleaner restriction

  • Intake‐air system is collapsed or restricted.

  • Fuel return line is restricted.

  • Excessive fuel pressure

  • Improper engine compression

  • Injector fuel leakage

  • Ignition system malfunction

WARNING:

The following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read following warnings before servicing 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 [LF].)

    (See AFTER SERVICE PRECAUTION [LF].)

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

1

What color is smoke coming from the exhaust system?

Blue

Burning oil is indicated.

Go to the next step.

White

Water in combustion is indicated.

Go to Step 3.

Black

Rich fuel mixture is indicated.

Go to Step 4.

2

Remove and shake the PCV valve.

Does the PCV valve rattle?

Yes

Inspect for the following:

  • Damaged valve guide, stems or valve seals

  • Blocked oil drain passage in cylinder head

  • Piston ring is not seated, seized or worn.

  • Damaged cylinder bore

If other driveability symptoms are present, return to diagnostic index to service any additional symptoms.

No

Replace the PCV valve.

3

Does the cooling system hold pressure?

Yes

Inspect for the following:

  • Cylinder head gasket leakage

  • Intake manifold gasket leakage

  • Cracked or porous engine block

If other driveability symptoms are present, return to diagnostic index to service any additional symptoms.

No

Inspect for cause.

4

Inspect for the following:

  • Air cleaner restriction

  • Collapsed or restricted intake‐air system

  • Restricted fuel return line

Are all items normal?

Yes

Go to the next step.

No

Service if necessary.

Repeat Step 4.

5

Connect the M-MDS to the DLC-2.

Turn the ignition switch to the ON position (Engine off).

Retrieve any DTCs.

Are there any DTCs displayed?

Yes

DTC is displayed:

Go to the appropriate DTC inspection.

(See DTC TABLE [LF].)

No

No DTC is displayed:

Go to the next step.

6

Install the fuel pressure gauge between the fuel pipe and the fuel distributor.

Start the engine and idle it.

Measure fuel line pressure during idle.

Is fuel line pressure correct during idle?

(See FUEL LINE PRESSURE INSPECTION [LF].)

Yes

Go to the next step.

No

Low:

High:

7

Perform the spark test.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [LF].)

Is strong blue spark visible at each cylinder?

Yes

Inspect the CMP sensor.

(See CAMSHAFT POSITION (CMP) SENSOR INSPECTION [LF].)

No

Repair or replace the malfunctioning part according to spark test result.

8

  • Verify test results.

    • If normal, return to diagnostic index to service any additional symptoms.

      (See SYMPTOM DIAGNOSTIC INDEX [LF].)

    • 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, replace the PCM.

        (See PCM REMOVAL/INSTALLATION [LF].)




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