4.
Read "DTC Status" parameter
If any DTCs relating to INJECTOR,HO2S,ECTS, or MAFS are stored, do ALL REPAIRS associated with those codes before proceeding with further troubleshooting
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode
Press F4(DTAL) to select DTC information from the DTCs menu.
Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
Read "DTC Status" parameter
Is parameter displayed "History(Not Present) fault"?
- History (Not Present) fault : DTC occurred but has been cleared.
- Present fault : DTC is occurring at present time.
YES
▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
NO
▶ Go to next step as below
The main purpose of this test is to identify potential engine mechanical condition problems and fuel and ignition systems problems that are not common to all cylinders. For best results, perform this test while maintaining as steady an rpm reading as possible.
Caution! Before beginning tests; set the parking brake, place gear selector in P or N and block drive wheels for safety.
Warm up the engine to normal operating temperature and let it idle.
Install Scan Tool and select INJECTOR #1 parameter on the Actuation Test mode
Monitor engine rpm and shut off the injector #1 by pressing "STRT(F1)" key
Repeat procedure on all injectors and record the engine rpm.
Specification : All cylinders should show an even RPM drop.
Was each cylinder’s rpm drop within the same value?
YES
▶ Go to next step as below
NO
▶ Cylinders with the least amount of RPM drop are not contributing their share of power. Go to "Fuel Injector Inspection" procedure and check the suspect cylinders
If the RPM loss between cylinders is quite large(200RPM or more) and engine has high mileage, there is possibility of engine wear. Perform compression test with pressure gauge to check the engine wear
