Rough Or Rolling Idle Or Stalls When Engaging Clutch
WARNING: This page is about a different variant/trim than selected.
- Preliminary Checks
Check engine oil level. Check for proper engine oil dipstick. Check for proper oil API rating (CG4/SH) and viscosity. Ensure engine oil has been changed within last 5000 miles. Check fuel quality. Check air filter minder to see if filter needs to be replaced. Repair any problems as necessary. If no problems are indicated, go to next step. - Perform KOEO On-Demand Self-Test
Perform KOEO ON-DEMAND SELF-TEST under QUICK TEST in SELF-DIAGNOSTICS - 7.3L DIESEL article. If no DTCs are present, go to next step. If any DTCs are present, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 7.3L DIESEL article and perform appropriate SYSTEM TESTS. - Perform KOEO Injector Electrical Self-Test
Perform KOEO INJECTOR ELECTRICAL SELF-TEST under QUICK TEST in SELF-DIAGNOSTICS - 7.3L DIESEL article. If no DTCs are present, go to next step. If any DTCs are present, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 7.3L DIESEL article and perform appropriate SYSTEM TESTS. - Check For Aerated Engine Oil
Perform TEST 10A: INJECTION CONTROL PRESSURE TEST (OIL AERATION/POOR IDLE) under ENGINE PERFORMANCE DIAGNOSTIC PROCEDURES in SYSTEM & COMPONENT TESTING - 7.3L DIESEL article. Repair any problems as necessary. If no problems are indicated, go to next step. - Check Source Of Aerated Engine Oil
Overfill engine oil with 2 qts. (1.9L) of specified oil. Raise rear of vehicle and support 10" from ground. Using scan tool, access ICP PID from PID/DATA MONITOR & RECORD menu. Start engine and run at Wide Open Throttle (WOT) for 3 minutes. If ICP PID reading is more than 1.75 volts, or more than 1800 psi (12,411 kPa), oil is aerating due to lack of defoaming agents. Change engine oil to meet CG4/SH specifications, ensure engine oil level is correct and go to next step. If ICP PID reading is 1.75 volts or less, or 1800 psi (12,411 kPa) or less, aeration is caused by an injector "O" ring leak or a hole in oil pick-up tube. Repair as necessary. - Injection Control Pressure Test
Using scan tool, access ICP PID from PID/DATA MONITOR & RECORD menu. Start engine and run at WOT for 3 minutes. If ICP reading is more than 1.75 volt, or more than 1800 psi (12,411 kPa), go to next step. If ICP reading is 1.75 volt or less, or 1800 psi (12,411 kPa) or less, concern is no longer present. - Low Idle Stability Test
Perform TEST 10B: LOW IDLE STABILITY (ICP PRESSURE) under ENGINE PERFORMANCE DIAGNOSTIC PROCEDURES in SYSTEM & COMPONENT TESTING - 7.3L DIESEL article. Repair any problems as necessary. If no problems are indicated, go to next step. - Check For Biased ICP Sensor
Perform TEST DC: INJECTION CONTROL PRESSURE SENSOR , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS - 7.3L DIESEL article. Repair any problems as necessary. If no problems are indicated, go to next step. - Check Fuel Pump Pressure
Perform TEST 8C: ELECTRIC FUEL PUMP PRESSURE TEST under ENGINE PERFORMANCE DIAGNOSTIC PROCEDURES in SYSTEM & COMPONENT TESTING - 7.3L DIESEL article. Repair as necessary. If fuel pump pressure is okay, go to next step. - Check Lubrication Pressure
Check engine oil level in high pressure oil pump reservoir. Reservoir is located on top of engine, near generator. See Figure. Oil level should be within 1" (25.4 mm) of inspection plug. Connect a 100 psi (689.5 kPa) oil pressure gauge to high pressure oil pump reservoir. Ensure engine is at operating temperature. With engine idling at 650 RPM, engine oil pressure should be 12 psi (69 kPa) or more. Raise engine speed to 3300 RPM and check engine oil pressure. Engine oil pressure should be 40-70 psi (276-482 kPa). If engine oil pressure is as specified, go to next step. If engine oil pressure is not as specified, check for cause of low oil pressure and repair as necessary. - KOER On-Demand Self-Test
Ensure engine is at normal operating temperature. Clear DTCs. Perform KOER ON-DEMAND SELF-TEST under QUICK TEST in SELF-DIAGNOSTICS - 7.3L DIESEL article. If DTC P1211 is present, perform TEST 9C: MONITOR ICP PID WHILE CRANKING under HARD START/NO-START DIAGNOSTIC PROCEDURES in SYSTEM & COMPONENT TESTING - 7.3L DIESEL article. Repair as necessary. If no DTCs are present, go to step 16. - Check Pressure Balance
Remove high pressure hose from right cylinder head. See Fig 1. Using Fuel/Oil/Turbo Protector Cap Set (T94T-9395-AH), install appropriate cap on high pressure hose fitting on right cylinder head. Using plug from Oil High Pressure Leakage Test Adapter Set (303-S626), install plug into high pressure hose. Using scan tool, access and record Injection Pressure Regulator (IPR) PID duty cycle with engine running at 3000 RPM. Turn engine off. Remove cap and plug, and reinstall high pressure hose to right cylinder head. Remove high pressure hose from left cylinder head. See Fig 2. Using fuel/oil/turbo protector cap set, install appropriate cap on high pressure hose fitting on left cylinder head. Using plug from oil high pressure leakage test adapter set, install plug into high pressure hose. Using scan tool, check IPR PID duty cycle with engine running at 3000 RPM. If difference in IPR PID duty cycles between right and left bank is more than 2 percent, remove cap and plug, and reinstall high pressure hose to left cylinder head. Go to next step. If difference in IPR PID duty cycles between right and left bank is 2 percent or less, replace IPR. Remove cap and plug, and reinstall high pressure hose to left cylinder head. - Check For Leak Source
Remove valve cover from cylinder bank with higher IPR duty cycle. With engine idling, check for bubbling around injector bores or oil gallery drain plugs. Or with engine off, apply about 100 psi (689 kPa) of compressed air to high pressure oil gallery. Injector spill spouts may require removal for visibility. If air bubbles are noticeable or leaks are heard, replace "O" rings on injectors or reseal oil galleries as necessary. If no leaks are detected, go to step 16. - Check Rough Idle
If a rough idle was present when vehicle was new or after a new high pressure oil pump was installed, go to next step. If a rough idle was not present when vehicle was new or after a new high pressure oil pump was installed, go to step 16. - Check High Pressure Oil Pump
Connect right side high pressure hose to left cylinder head and plug left hose. Using scan tool, access and monitor IPR PID duty cycle at idle. Compare this reading with the reading for the left cylinder head taken in step 12) . If difference in readings is .2 volt or less, or 2 percent or less, go to next step. If difference in readings is more than .2 volt, or 2 percent, ensure high pressure hoses are clear and replace high pressure oil pump. - KOER Cylinder Contribution Self-Test
Perform KOER CYLINDER CONTRIBUTION SELF-TEST under QUICK TEST in SELF-DIAGNOSTICS - 7.3L DIESEL article. If a faulty cylinder is identified during testing, go to next step. If a faulty cylinder is not identified during testing, go to step 18. - Check For Engine Wear
Perform TEST 11: CRANKCASE PRESSURE TEST under ENGINE PERFORMANCE DIAGNOSTIC PROCEDURES in SYSTEM & COMPONENT TESTING - 7.3L DIESEL article. If crankcase pressure reading is more than 3 in. H2O, or compression pressure is less than 350 psi (2413 kPa) and different from adjacent cylinder by 50 psi (345 kPa) or more, check engine mechanical condition (compression rings, cylinder bores, valves, etc.). Repair as necessary. If crankcase pressure reading is 3 in. H2O or less, or compression pressure is 350 psi (2413 kPa) or more and different from adjacent cylinder by less than 50 psi (345 kPa), replace injector in identified cylinder. - Check For Incorrect Injector Application
Remove engine valve covers. Ensure correct injectors are installed. Part number is stamped on top of each injector. Replace injector if necessary. If injector numbers are correct for application, cause of rough idle cannot be determined. Compare idle performance to vehicles with similar powertrain.