Home

< Previous   Next >

2008 - MX-5 - Engine

NO.4 HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK [LF]



4

HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK

DESCRIPTION

  • The starter cranks engine at normal speed but engine requires excessive cranking time before starting.

  • The battery is in normal condition.

POSSIBLE CAUSE

  • Erratic signal to ignition coil

  • Vacuum leakage

  • Poor fuel quality

  • Starting system malfunction

  • Spark plug malfunction

  • Air leakage from intake-air system

  • Erratic signal from CKP sensor

  • Erratic signal from CMP sensor

  • Improper air/fuel mixture ratio control

  • Air cleaner restriction

  • Improper operation of electronic throttle control system

  • PCV valve malfunction

  • Inadequate fuel pressure

  • Purge solenoid valve malfunction

  • MAF sensor contamination

  • Incorrect MAF sensor GND voltage

  • Restriction in exhaust system

  • EGR valve malfunction

  • Pressure regulator malfunction (built-in fuel pump unit)

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 [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

Inspect for the following:

  • Vacuum leakage

  • Proper fuel quality (such as proper octane, contamination, winter/summer blend)

  • Loose bands on intake-air system

  • Cracks on intake-air system parts

  • Intake-air system restriction (such as air cleaner element, fresh air duct.)

Are all items normal?

Yes

Go to the next step.

No

Service if necessary.

Repeat Step 1.

2

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.

3

Is engine overheating?

Yes

Go to symptom troubleshooting “No.17 Cooling system concerns-Overheating”.

(See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [LF].)

No

Go to the next step.

4

Inspect the ignition coil related wiring harness condition (intermittent open or short circuit) for all cylinders.

Are wiring harness conditions normal?

Yes

Go to the next step.

No

Repair the wiring harnesses.

5

Inspect the spark plug conditions.

Is spark plug wet, covered with carbon or grayish white?

Yes

Spark plug is wet or covered with carbon:

Inspect for fuel leakage from fuel injector.

Spark plug is grayish white:

Inspect the fuel injector for clogging.

No

Install the spark plugs on original cylinders.

Go to the next step.

6

Visually inspect the CKP sensor and teeth of crankshaft pulley.

Are the CKP sensor and teeth of crankshaft pulley normal?

Yes

Go to the next step.

No

Replace the malfunctioning part.

7

Remove and shake the PCV valve.

Does the PCV valve rattle?

Yes

Go to the next step.

No

Replace the PCV valve.

8

Attempt to start engine at part throttle.

Does engine run smoothly at part throttle?

Yes

Inspect the electronic throttle control system operation.

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

No

Go to the next step.

9

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

Short check connector terminal F/P to body GND using a jumper wiring.

Turn the ignition switch to the ON position.

Is fuel line pressure correct with ignition switch ON?

(See FUEL LINE PRESSURE INSPECTION [LF].)

Yes

Go to the next step.

No

Zero or low:

Inspect the fuel pump relay and the fuel pump circuit.

Inspect the fuel line for clogging.

If there is no malfunction, replace the fuel pump unit.

(See FUEL PUMP UNIT REMOVAL/INSTALLATION [LF].)

High:

Replace the fuel pump unit.

(See FUEL PUMP UNIT REMOVAL/INSTALLATION [LF].)

10

Is the fuel line pressure held after ignition switch is turned off?

(See FUEL LINE PRESSURE INSPECTION [LF].)

Yes

Go to the next step.

No

Inspect the fuel injector.

(See FUEL INJECTOR INSPECTION [LF].)

If the fuel injector is normal, replace the fuel pump unit.

(See FUEL PUMP UNIT REMOVAL/INSTALLATION [LF].)

11

Disconnect a vacuum hose from purge solenoid valve and plug opening end of vacuum hose.

Start engine.

Is starting condition improved?

Yes

Inspect if the purge solenoid valve is stuck open.

No

Go to the next step.

12

Inspect the MAF sensor for following:

  • Contamination

  • MAF sensor terminal B voltage (GND circuit)

Is there any contamination?

Yes

Repair or replace the malfunctioning part.

No

Go to the next step.

13

Visually inspect the exhaust system part.

Is there any deformed exhaust system part?

Yes

Replace the suspected part.

No

Go to the next step.

14

Inspect engine condition while tapping EGR valve housing. Does engine condition improve?

Yes

Replace the EGR valve.

(See EGR VALVE REMOVAL/INSTALLATION [LF].)

No

Go to the next step.

15

Inspect the starting system.

(See STARTER INSPECTION [LF].)

Is starting system normal?

Yes

Inspect for loose connectors or poor terminal contact.

If there is no malfunction, remove EGR valve and visually inspect for mechanically stuck EGR valve.

No

Repair or replace components as required.

16

  • 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].)




< Previous   Next >
Back to Top
© 2012 Mazda North American Operations, U.S.A.