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Home › Mazda › 2006 › 6 Mazdaspeed › Repair and Diagnosis › Engine Performance › System › Symptom Troubleshooting [Engine Control System L3 With TC) › No. 12 Lack/Loss Of Power-Acceleration/Cruise › Diagnostic procedure

Diagnostic procedure

DIAGNOSTIC PROCEDURE

STEP INSPECTION RESULTS ACTION
1 Verify the following:
  • Fuel quality (proper octane, contamination, winter/summer blend)
  • Air cleaner restriction or dirty
  • Intake-air system restriction or leakage
  • Charge air cooler condition (restriction or damaged)
  • Turbocharger compressor-to-intake manifold duct loose connection
  • Leakage at exhaust manifold or turbocharger mounting flange
  • Vacuum leakage
  • Clutch slippage
  • Brake dragging

Are all items normal?		 Yes Go to the next step.
No Service if necessary.
Repeat Step 1.
2 Perform the self-test function using the WDS or equivalent.
Turn the ignition switch to the ON position.
Retrieve any DTCs.
Is a DTC displayed?		 Yes DTC is displayed: 
Go to the appropriate DTC test.
(See DTC TABLE ).
No No DTC is displayed: 
Go to the next step.
3 Is the engine overheating? Yes Go to symptom troubleshooting "NO.17 COOLING SYSTEM CONCERN-OVERHEATING."
(See NO. 17 COOLING SYSTEM CONCERNS-OVERHEATING ).
No Go to the next step.
4 Perform the EGR system operation inspection.
(See EGR CONTROL SYSTEM INSPECTION ).
Does the EGR system operate properly?		 Yes Go to the next step.
No Inspect or replace the malfunctioning parts, according to the inspection results.
5 Perform the A/C Cut-off Operation Inspection.
(See A/C CUT-OFF CONTROL SYSTEM INSPECTION ).
Does the A/C Cut-off Operation work properly?		 Yes Go to the next step.
No Repair or replace malfunctioning parts, according to the inspection results.
6 Perform the TP sweep inspection.
(See THROTTLE POSITION (TP) SWEEP INSPECTION ).
Does the variable swirl system work properly?		 Yes Visually inspect throttle body (damaged/scratching). If normal, go to the next step.
No Inspect or replace the malfunctioning parts, according to the inspection results.
7 Perform the Variable Swirl Control System Operation Inspection.
(See VARIABLE SWIRL SYSTEM OPERATION INSPECTION ).		 Yes Go to the next step.
No Inspect or replace the malfunctioning parts, according to the inspection results.
8 Perform the Variable Valve Timing Control System Operation Inspection.
(See VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION INSPECTION ).
Does the variable valve timing control system work properly?		 Yes Go to the next step.
No Inspect or replace the malfunctioning parts, according to the inspection results.
9 Perform the Purge Control System Operation Inspection.
(See PURGE CONTROL SYSTEM INSPECTION ).
Does the purge control system work properly?		 Yes Go to the next step.
No Inspect or replace the malfunctioning parts, according to the inspection results.
10 Perform Fuel Pump Speed Control Inspection.
(See FUEL PUMP SPEED CONTROL INSPECTION ).
Does the fuel pump speed control work properly?		 Yes Go to the next step.
No Inspect or replace the malfunctioning parts, according to the inspection results.
11 Perform the Wastegate Control System Operation Inspection.
(See WASTEGATE CONTROL SYSTEM OPERATION INSPECTION ).
Does the wastegate control system work properly?		 Yes Go to the next step.
No Inspect or replace the malfunctioning parts, according to the inspection results.
12 Connect the WDS or equivalent to DLC-2.
Access and monitor following Plus using the data monitor function.
  • ECT
  • MAF
  • IAT
  • IAT2
  • APP
  • TP
  • MAP
  • FP (Low side pressure line)
  • VSS

Do the PIDs indicate correct values under trouble condition?
(See USING THE WDS OR EQUIVALENT ).		 Yes Go to the next step.
No Inspect and repair or replace suspected parts and related harnesses.
If the malfunction remains, perform the intermittent concern troubleshooting procedure.
(See INTERMITTENT CONCERN TROUBLESHOOTING ).
13 Inspect CMP and CKP sensor for following;
 Yes Repair or replace the malfunctioning part according to the inspection results.
No Go to the next step.
14 Remove and shake PCV valve.
Does the PCV valve rattle?		 Yes Go to the next step.
No Replace the PCV valve.
15 Inspect spark plug condition.
Is spark plug wet, covered with carbon or grayish white?		 Yes Spark plug is wet or covered with carbon:
Perform the Spark Test and repair or replace malfunctioning part according to inspection result.
(See SPARK TEST ).
Spark plug is grayish white.
Go to Step 23.
No Install spark plugs on original cylinders.
Go to the next step.
16 Inspect for restriction in exhaust system and three-way catalytic converter (TWC).
Is there any restriction?		 Yes Replace malfunctioning part.
No Go to the next step.
17 Remove parts necessary to inspect turbocharger without remove the turbocharger.
Inspect if turbocharger compressor wheel is bent, damaged, or Interfering with housing on vehicle.
(See TURBOCHARGER INSPECTION ).
Is there any problem?		 Yes Replace turbocharger.
No Go to the next step.
18 Inspect turbocharger compressor wheel locknut is loose or has fallen down inside turbocharger.
Is there any problem?		 Yes Replace turbocharger.
No Go to the next step.
19 Inspect if turbocharger compressor wheel by hand.
Does wheel turn easily and smoothly?		 Yes Go to the next step.
No Replace turbocharger.
20 Inspect turbocharger turbine wheel is damaged, cracked or interfering with housing on vehicle.
NOTE:
  • Inspect all fins on each turbine wheel.

Is there any problem?		 Yes Replace turbocharger.
No Go to the next step.
21 Is any engine oil found inside turbocharger turbine housing? Yes Excessive amount of oil is found:
Replace turbocharger.
Small amount of oil is found:
Wipe oil out of vehicle, then Go to the next step.
No Go to the next step.
22 Is any engine oil found inside turbocharger compressor housing? Yes Wipe oil out vehicle and install all removed parts in Step 16. Then, Go to the next step.
No Turbocharger is normal.
Install all parts removed in Step 17.
Then, Go to the next step.
23 Inspect for leakage in fuel line.
Is there any fuel leakage found?		 Yes Repair or replace suspected part.
No Go to the next step.
24 Access and monitor FUEL_PRES PID.
Is the FUEL_PRES PID value within the specification?
(See USING THE WDS OR EQUIVALENT ).		 Yes Go to Step 27.
No Go to the next step.
25 Replace the high pressure fuel pump.
Monitor FUEL_PRES PID.
Is the FUEL_PRES PID value within the specified?
(See USING THE WDS OR EQUIVALENT ).		 Yes Troubleshooting is completed.
Go to Step 30.
No Go to the next step.
26 Inspect the fuel pressure sensor.
(See FUEL PRESSURE SENSOR INSPECTION ).
Is the fuel pressure sensor normal?		 Yes Go to the next step.
No Replace the delivery pipe.
27 Connect the fuel pressure gauge between fuel pump and high pressure fuel pump.
Measure the fuel pressure line of the low pressure side.
(See FUEL LINE PRESSURE INSPECTION ).
Is the fuel pressure within the specification?		 Yes Go to the next step.
No Inspect for the following:
  • Fuel line restriction
  • Fuel filter clogging

If normal replace the fuel pump.
28 Inspect fuel injector for each cylinder.
(See FUEL INJECTOR INSPECTION ).
Are fuel injectors normal?		 Yes Go to the next step.
No Replace suspected fuel injector.
(See FUEL INJECTOR REMOVAL/INSTALLATION ).
29 Measure compression pressure for each cylinder.
(See COMPRESSION INSPECTION ).
Are compression pressures within the specification?		 Yes Replace the injector driver module.
If the problem remains, overhaul the engine.
No Inspect for the following:
  • Damaged valve seat
  • Worn valve stem and valve guide
  • Worn or stuck piston ring
  • Worn piston, piston ring or cylinder
  • Improper valve timing

Service if necessary.
30 Verify test results.
  • If normal, return to the diagnostic index to service any additional symptoms.
  • If a malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform the 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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