So the only code is P0306? Try these steps. Circuit Description Crankshaft position sensor and camshaft position sensor are used to detect misfire. VCM monitors crankshaft speed and detects deceleration or acceleration of crankshaft that are not associated with normal engine speed. Crankshaft position sensor information is compared to engine speed and engine load to determine if a misfire occurred. If a misfire is present, crankshaft position is compared to camshaft position sensor signal to determine which cylinder misfired. Information will be stored in separate accumulators for each cylinder. VCM evaluates number of misfires in each accumulator. A random misfire is determined if accumulators are somewhat even or if 3 or more cylinders are misfiring. VCM also utilizes input from front wheel speed sensor to determine if a rough road condition exists which could cause crankshaft acceleration and deceleration. Diagnostic will not run if a rough road condition exists. DTC will set when the following conditions are present: à   No TP sensor DTCs are set. à   No MAF DTCs are set. à   No IC control DTCs are set. à   No VSS DTCs are set. à   No crankshaft position sensor DTCs are set. à   Rough road condition is not detected. à   ECT is greater than or equal to 19 °F (-7 °C). à   Engine speed is 600-5600 RPM. à   System voltage is 9-16 volts. à   Positive throttle position change is less than 4.9 percent for 100 milliseconds. à   Negative throttle position change is less than 2.9 percent for 100 milliseconds. à   Misfire is detected. Diagnostic Procedures 1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the F - BASIC TESTING - 5.0L article. After performing OBD system check, go to next step. 2. Check if any other DTCs are set. If any other DTCs are set, go to applicable DTC test. If no other DTCs are set, go to next step. 3. Install scan tool. With engine idling, monitor MAP sensor voltage using scan tool. If MAP sensor voltage is greater than 4 volts, go to DTC P0108. If MAP sensor voltage is less than 4 volts, go to next step. 4. Duplicate conditions required for misfire. Check if DTC is set as current for this ignition cycle. If DTC is set as current, go to next step. If DTC is not set as current, go to step 9). 5. Install Spark Tester (J 26792) on spark plug wire No. 6. Disconnect fuel injector harness at intake manifold. Crank engine. Spark should jump tester gap. If spark is adequate, go to next step. If spark is not adequate, go to step 10). 6. Remove spark plug from affected cylinder. Inspect spark plugs for wear, excessive air gap, cracks or fouling. Swap spark plug with a plug from another cylinder that is not experiencing misfire. Monitor misfire index using scan tool. If misfire index increases for cylinder with suspect plug, go to next step. If misfire index does not increase for cylinder with suspect plug, go to step 11). 7. Perform a cylinder compression test. If a problem was found, go to step 13). If a problem was not found, go to next step. 8. Diagnose injector circuit. See the F - BASIC TESTING - 5.0L article. If a problem was found, go to next step. If a problem was not found, go to step 12). 9. Misfire is intermittent and not currently occurring. See DIAGNOSTIC AIDS. 10. Perform enhanced ignition system check. See the F - BASIC TESTING - 5.0L article. 11. Replace spark plug. After replacing spark plugs, go to step 14). 12. Repair circuit as necessary. After repairs, go to step 14). 13. Repair problem as necessary. After repairs, go to next step. 14. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC number that was set. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2). 15. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test. Diagnostic Aids Misfire index can be monitored using scan tool. Each cylinder has a misfire counter for current and history. Current misfire counter can be used to determine which cylinder is misfiring. Current misfire counter for a currently misfiring cylinder will be increased by a factor of 2. If VCM is unable to determine which cylinder is misfiring, counter will increase by a factor of one for each cylinder that may have misfired. An intermittent misfire may be caused by spark plug wires, coil wires, contaminated fuel or low fuel level. Ensure spark plug wires are securely connected to spark plugs and distributor cap. Check wire routing for crossfiring. If misfire occurs during damp weather, check for worn plug wires. Spray wires with water with engine running and check for spark to jump from wires. If spark is present, replace wires. Check fuel condition and quality. Dirty or contaminated fuel could cause misfire condition. If fuel level is low, contaminates on bottom of tank could be introduced into fuel system. Severely out of balance tires could result in DTC setting. Road test vehicle and check for out of balance tires or drive line components.
Either the spark is weak, the plug or coil is weak, or compression is lower than the other cylinders.
Test the injector for actually firing.
Injector Coil Test (CSI) 1. Perform on-board diagnostic test. Diagnose any Diagnostic Trouble Code (DTC) present. If DTC is not present, go to next step. 2. Turn ignition off. Relieve fuel pressure. Connect Fuel Injector Tester (J-39021) to battery positive. Connect Injector Switch Box (J-39021-210). Set amperage on fuel injector tester to 0.5 amp. Connect DVOM to fuel injector tester. Connect Tech 1 scan tool and monitor engine coolant temperature. If coolant temperature is 50-95 °F (10-35 °C), go to step 4). If coolant temperature is not as specified, go to next step. 3. Allow engine to warm or cool as necessary. If engine coolant temperature is now 50-95 °F (10- 35 °C), go to next step. 4. Using fuel injector tester, press PUSH TO START TEST button and monitor DVOM reading. Perform this test to each injector. Voltage reading should be 5.44-7.53 volts. If voltage reading is as specified, go to next step. If voltage reading is not as specified, perform injector balance test. See CENTRAL SEQUENTIAL PORT INJECTOR BALANCE TEST (CSI). 5. Replace faulty injector nozzle and poppet assembly and then proceed to next step. 6. Using Tech 1 scan tool, select DTC, CLEAR INFO. Start engine. If engine starts and continues to run, go to next step. If engine does not start or starts and dies, repeat step 2). 7. Warm engine to normal operating temperature. Using scan tool, select DTC, FAILED THIS IGN. If DTC(s) are present, diagnose DTC(s). If DTC(s) are not present, go to next step. 8. Using scan tool, select CAPTURE INFO, REVIEW INFO. If additional DTC(s) are present, diagnose DTC(s). If DTC(s) are not present, system is okay.
Sunday, August 22nd, 2010 AT 2:15 PM
