STEP
INSPECTION
ACTION
1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
• Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record FREEZE FRAME DATA on the repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
• Verify related Service Information availability.
• Is any related Service Information available?
Yes
Perform repair or diagnosis according to the available Service Information.
• If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
VERIFY RELATED PENDING CODE OR STORED DTCS
• Turn the ignition switch off, then to the ON position (engine off).
• Verify related PENDING CODE or stored DTCs.
• Are any DTCs present other than the following:
-
― P0171:00, P0174:00, P2195:00 or P2197:00?
Yes
Go to the appropriate DTC troubleshooting procedures.
No
Go to the next step.
4
PERFORM VISUAL INSPECTION ON INTAKE AIR SYSTEM AND ALL VACUUM HOSES
• Turn the ignition switch off.
• Check the intake air system for leaks, obstructions, and damage.
• Inspect the entire length of all the vacuum hoses for:
-
― Proper connections― Damage or cracks― Damaged or cracked vacuum hose joint
• Verify the integrity of the positive crankcase ventilation (PCV) system.
• Verify that the PCV valve part number is correct.
• Is a concern present?
Yes
Repair if necessary. Then go to Step 7.
No
Go to the next step.
5
INSPECT FOR PRESENCE OF VACUUM LEAK
-
Note
-
• Fuel trim values at idle are more sensitive to a vacuum leak. The vacuum leak (unmetered air) represents a larger portion of the total air flow at idle than at part throttle.• The BARO PID is not a commended PID to monitor when diagnosing a vacuum leak. BARO is calculated during high engine load, when the vacuum leak represents a small portion of the total air flow• When calculating the total fuel correction in the following steps, if LONGFT1 equals +13% and SHRTFT1 equals +23%, the total fuel correction for bank 1 equals +36%. If LONGFT2 equals +24% and SHRTFT2 equals -3% the total fuel correction for bank 2 equals +21%.• If the freeze frame ECT PID is available, stabilize the engine at the temperature recorded by the freeze frame ECT PID. If the freeze frame ECT PID is not available, maintain the engine coolant temperature between 82—101 °C {180—215 °F} and the intake air temperature at less than 46 °C {115 °F}.
• Turn the ignition switch to the ON position (engine running).
• Access the PCM and monitor the ECT, CHT and IAT PIDs.
• Access the PCM and monitor the LONGFT1, SHRTFT1, LONGFT2 and SHRTFT2 PIDs.
• Allow the engine to stabilize at the temperature necessary to recreate the concern.
-
Note
-
• If the engine speed cannot be increased to 3,500 rpm, increase the engine speed to the maximum RPM without activating RPM limiting.
• Add and record the LONGFT PID value to the SHRTFT PID value for each bank, correction at idle.
• Increase the engine speed to 3,500 rpm for 10 s. Record the LONGFT1, SHRTFT1, LONGFT2, and system SHRTFT2 PID values.
• Add and record the LONGFT PID value to the SHRTFT PID value for each bank, correction at 3,500 rpm.
• Is the total fuel correction value difference between idle and 3,500 rpm less than 15%?
Yes
No vacuum leak is present. Go to Step 8.
No
Go to the next step.
6
LOCATE VACUUM LEAK
-
Caution
-
• Do not clamp or pinch a hard plastic hose. Use a vacuum cap or equivalent to restrict the hose.
-
Note
-
• Restricting the EVAP vapor hose while the EVAP emission canister is purging may shift the SHRTFT. Perform a visual inspection if necessary.• When monitoring for a decrease in the SHRTFT PIDs in the following steps, if SHRTFT1 equals +15% and the hose is restricted, SHRTFT1 decreases to -7%. The total decrease in the SHRTFT PIDs equals 22%.
• Locate the vacuum hose joint for the intake air and PCV systems.
• Access the PCM and monitor the SHRTFT1 and SHRTFT2 PIDs.
• Restrict the vacuum lines one at a time for 30 s. If a vacuum leak in the intake is present, the SHRTFT PID values decrease as the hose is restricted.
• Is the decrease in the SHRTFT PIDs more than 15% when one of the vacuum hoses is restricted?
Yes
Repair if necessary. Then go to the next step.
No
Inspect the intake air system for a vacuum leak in the intake manifold or intake gaskets. Repair if necessary. Then go to the next step.
7
VACUUM LEAK REPAIR VERIFICATION
-
Note
-
• If the freeze frame ECT PID is available, stabilize the engine at the temperature recorded by the freeze frame ECT PID. If the freeze frame ECT PID is not available, maintain the engine coolant temperature between 82—101 °C {180—215 °F} and the intake air temperature less than 46 °C {115 °F}.
• Access the PCM and monitor the SHRTFT1 and SHRTFT2 PIDs.
• Allow the engine to stabilize at the temperature necessary to recreate the concern.
• Record the SHRTFT1 and SHRTFT2 PID values.
• Turn the ignition switch off.
• Repair the vacuum leak.
• Turn the ignition switch to the ON position (engine running).
• Allow the engine to stabilize at the temperature necessary to recreate the concern.
• Access the PCM and monitor the SHRTFT1 and SHRTFT2 PIDs.
• Compare the recorded SHRTFT PID values, prior to the no vacuum leak repair, to the current SHRTFT PID values.
• Is the decrease in the SHRTFT PIDs more than 15%?
Yes
Reset the keep alive memory. Then go to Step 26.
No
A vacuum leak is still present. Go to Step 6.
8
INSPECT FUEL PRESSURE
-
Warning
-
• Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death. Fuel can also irritate skin and eyes. To prevent this, always complete the “BEFORE REPAIR PROCEDURE”.
-
Note
-
• For vehicle specific fuel pressure ranges, refer to the “FUEL LINE PRESSURE INSPECTION”.
• Remove the jumper wire(s).
• Connect the A/F sensor connector.
• Relieve the fuel pressure.
• Connect the mechanical fuel pressure gauge.
• Pressurize the fuel system.
• Turn the ignition switch to the ON position (engine running).
• Allow the fuel pressure to stabilize.
• Turn the ignition switch off.
• Turn the ignition switch to the ON position (engine running).
• Measure the fuel pressure.
• Is the fuel pressure within the range for the vehicle being diagnosed?
Yes
Go to Step 19.
No
Go to the next step.
9
INSPECT FUEL LINE PRESSURE
• Turn the ignition switch off.
• Connect the mechanical fuel pressure gauge.
• Connect the FP connector.
• Turn the ignition switch to the ON position (engine off).
• Pressurize the fuel system.
• Cycle the key several times to charge the fuel system.
• Relieve the fuel pressure.
• Is the fuel pressure within range?
Yes
Go to Step 12.
No
Go to the next step.
10
INSPECT FUEL PUMP GROUND CIRCUIT FOR OPEN CIRCUIT IN WIRING HARNESS
-
Note
-
• Refer to the Wiring Diagrams Manual for schematic and connector information.
• Turn the ignition switch off.
• Disconnect the FP and fuel pump relay connectors.
• Verify that continuity between FP (wiring harness-side connector) terminal D and ground.
• Is there any continuity?
Yes
Go to the next step.
No
Repair for an open circuit, then go to Step 26.
11
INSPECT FUEL PUMP POWER CIRCUIT FOR OPEN CIRCUIT IN WIRING HARNESS
-
Note
-
• Refer to the Wiring Diagrams Manual for schematic and connector information.
• Turn the ignition switch off.
• Disconnect the FP and fuel pump relay connectors.
• Verify that continuity between FP (wiring harness-side connector) terminal B and fuel pump relay (wiring harness-side connector) terminal C.
• Is there any continuity?
Yes
Go to Step 14.
No
Repair for open circuit, then go to Step 26.
12
CALCULATE PERCENTAGE OF ETHANOL IN FUEL
-
Note
-
• Use the illustration as an example for calculating the percentage of ethanol using the following steps. If the separation level is at 14 ml {14 cc, 0.85 in3}, the calculation is; 14 minus 4, then multiply by 5 to equal 50. The percentage of ethanol in the fuel is 50%
am6xuw00002541
• Turn the ignition switch off.
• Take the recorded separation level from the previous step and subtract the amount of water added
• Multiply the new value by 5. This new value is the percentage of ethanol in the fuel
• Record the calculated percentage of ethanol in the fuel
• Is any ethanol present in the fuel?
Yes
Go to the next step.
No
Go to Step 14.
13
DETERMINE IF PERCENTAGE OF ETHANOL IN FUEL IS LESS THAN 10%
• Verify the recorded calculated percentage of ethanol in the fuel.
• Is the calculated percentage of ethanol in the fuel less than 10%?
Yes
Go to the next step.
No
Replace the fuel.
Advice the customer of the correct fuel type required for this vehicle. Refer to the Owner's Manual Literature for additional information.
Go to Step 26.
14
INSPECT FUEL PRESSURE LEAKDOWN
-
Note
-
• When the fuel pump is commanded off, the fuel pressure may substantially decrease and then stabilize• During output state control, the fuel pump stays commanded on for only about 5 s.
• Mechanical fuel pressure gauge connected.
• Turn the ignition switch to the ON position (engine running).
• Allow the fuel pressure to stabilize.
• Turn the ignition switch off.
• Monitor the fuel pressure for 5 min.
• Is the fuel pressure above fuel hold pressure after 5 min?
Yes
Go to Step 16.
No
Go to the next step.
15
INSPECT FUEL INJECTOR FLOW AND LEAKAGE
-
Note
-
• Observe the Warnings, Cautions, and Notes.
• Inspect the fuel injectors for leakage and flow rate using the injector flow tester or other method such as inspecting the intake manifold for fuel.
• Are the test results satisfactory?
Yes
Go to the next step.
No
Replace the suspect fuel injector, then go to Step 26.
16
MONITOR FUEL PRESSURE WHILE ROAD TESTING VEHICLE
-
Warning
-
• Strict observance of posted speed limits and attention to driving conditions are mandatory when performing the road test. Failure to follow these instructions may result in personal injury.
-
Note
-
• Some concerns may only be present during certain fuel level conditions. Determine the fuel level at the time of the concern. Access the information from the customer information worksheet and the customer.
• Turn the ignition switch off.
• Securely route the mechanical gauge so that the gauge is viewable while road testing the vehicle.
• Start the engine and run it at idle.
• Warm up the engine to normal operating temperature.
• Monitor the mechanical gauge.
• From a stop, accelerate to 89 km/h (55 mph) at full throttle.
• Repeat 3 times.
• Is the fuel pressure always greater than 240 kPa {2.45 kgf/cm2, 34.8 psi}?
Yes
Unable to duplicate or identify the concern at this time.
Go to Step 26.
No
Go to the next step.
17
INSPECT FUEL SUPPLY LINE FOR RESTRICTION
-
Note
-
• Observe the Warnings, Cautions, and Notes.
• Turn the ignition switch off.
• Disconnect the fuel supply line at the fuel rail.
• Disconnect the fuel supply line at the fuel pump.
• Verify the fuel supply line for restriction.
• Apply 21—34 kPa {0.22—0.34 kgf/cm2, 3.1—4.9 psi} air pressure to the fuel supply line.
• Does air flow freely through the line?
Yes
Replace the fuel filter (low-pressure side).
Go to the next step.
No
Repair the cause of the restriction, then go to Step 26.
18
VERIFY FUEL SYSTEM REPAIRED
-
Warning
-
• Strict observance of posted speed limits and attention to driving conditions are mandatory when carrying the road test. Failure to follow these instructions may result in personal injury.
• Start the engine and run it at idle.
• Warm up the engine to normal operating temperature.
• Monitor the mechanical gauge.
• From a stop, accelerate to 89 km/h (55 mph) at full throttle.
• Repeat this 3 times.
• Is the fuel pressure always greater than 240 kPa {2.45 kgf/cm2, 34.8 psi}?
Yes
The test is complete and no concerns are present.
Go to Step 26.
No
Replace the fuel pump unit, then go to Step 26.
19
VERIFY FUEL SYSTEM FOR PRESSURE STABILITY-FAST LEAKDOWN
• Mechanical fuel pressure gauge connected.
• Turn the ignition switch to the ON position (engine running).
• Allow the fuel pressure to stabilize
• Record the stabilized reading
• Turn the ignition switch off.
• Monitor the fuel pressure for 10 s.
• Measure the fuel line pressure after 10 s.
• Does the fuel pressure remain within 34 kPa {0.35 kgf/cm2, 4.9 psi} of the recorded reading after 10 s?
Yes
Go to Step 21.
No
Go to the next step.
20
INSPECT FOR EXTERNAL FUEL LEAK
• Inspect the fuel tank, lines, and filler pipe for a fuel leak.
• Is a concern present?
Yes
Repair for fuel leakage, then go to Step 26.
No
Go to Step 23.
21
VERIFY FUEL SYSTEM FOR PRESSURE STABILITY-SLOW LEAKDOWN
• Continue to monitor the fuel pressure for 1 min.
• Does the fuel pressure remain within 34 kPa {0.35 kgf/cm2, 4.9 psi} of the recorded reading after 1 min?
Yes
Go to the next step.
No
Go to Step 15.
22
DETERMINE IF THE PERCENTAGE OF ETHANOL IN FUEL IS LESS THAN 10%
• Check the recorded (calculated) percentage of ethanol in the fuel referring to Step 12 and 13.
• Is the calculated percentage of ethanol in the fuel less than 10%?
Yes
Go to the next step.
No
Replace the fuel.
Advice the customer of the correct fuel type required for this vehicle. Refer to the Owner's Manual Literature for additional information.
Go to Step 26.
23
INSPECT FUEL INJECTOR OPERATION
• Perform the “Fuel Injector Operation Inspection” for the right bank (with DTC P0171:00) or the left bank (with DTC P0174:00).
• Does the fuel injector operate properly?
Yes
Go to the next step.
No
Replace the suspect fuel injector, then go to Step 26.
24
VERIFY FUNCTIONALITY OF MAF SENSOR
-
Note
-
• MAF PID value of less than 0.6 V may indicate an incorrectly installed air cleaner or a leak in the intake-air system.
• Start the engine and run it at idle.
• Allow the engine to stabilize at the correct operating temperature.
• Access and monitor the MAF PID.
• Inspect that the MAF PID at idle and P/N position is not greater than 30% of the normal MAF listed. Reference Values or not greater than 1.3 V.
(See PCM INSPECTION [MZI-3.7].)
• Is the PID value within the expected range?
Yes
Unable to duplicate or identify the concern at this time.
Go to Step 26.
No
Go to the next step.
25
INSPECT TO ISOLATE MAF SENSOR FROM LEAN DRIVEABILITY OCCURRENCE
-
Note
-
• Due to increasingly stringent emission/OBD requirements, a fuel system DTC on some vehicles can be generated without a noticeable drivability concern with or without the MAF sensor disconnected. Under these conditions, if the MAF PID indicates a MAF sensor concern, replace the MAF sensor.
• Turn the ignition switch off.
• Disconnect the MAF/IAT sensor connector.
• Start the engine and run it at idle.
• Drive the vehicle on the road.
• Does the lean drivability symptom (lack of power, spark knock/detonation, buck/jerk or hesitation/surge on acceleration) disappear?
Yes
Replace the MAF/IAT sensor, then go to the next step.
No
Go to the next step.
(The system is correctly at this time. The concern may have been caused by a loose or corroded connector.)
26
VERIFY TROUBLESHOOTING OF DTC P0171:00, P0174:00 HAS BEEN COMPLETED
• Verify that all disconnected connectors are reconnected.
• Clear the DTC from the PCM memory using the M-MDS.
• Perform the OBD DRIVE MODE up to Misfire, Fuel and HO2S Monitors (Step 11).
• Retrieve DTCs using the M-MDS.
• Is the PENDING CODE for this DTC present?
Yes
Repeat the inspection from Step 1.
• If the malfunction recurs, replace the PCM.
Go to the next step.
No
Go to the next step.
27
VERIFY AFTER REPAIR PROCEDURE
• Perform the “AFTER REPAIR PROCEDURE”.
• Are any DTCs present?
Yes
Go to the applicable DTC inspection.
No
Troubleshooting completed.