6-4
DIAGNOSTIC TROUBLESHOOTING
6
Excessive fuel consumption. Fouled spark plug(s). Check spark plugs. (See “Spark Plugs” on
page 7-8.)
Faulty ignition coil. Check ignition coils. (See “Ignition Coils”
on page 7-8.)
Faulty fuel injector. Check fuel injectors. (See “Injectors” on
page 7-9.)
Valve clearance adjustment. Check valve clearance. (See “Valve
Clearance Check and Adjustment” on
page 5-3.)
Vacuum leak. Check intake manifold vacuum. (See
“Intake Manifold Vacuum Test” on
page 5-2.)
Throttle body gasket leaking air. Check throttle body and gasket. (See
“Throttle Body” on page 7-4.)
Faulty throttle position sensor. Check throttle position sensor. (See
“Throttle Position Sensor” on page 7-3.)
Incorrect fuel. Use proper fuel.
Faulty oxygen sensor. Check oxygen sensor. (See “Oxygen
Sensor” on page 7-6.)
Restricted air cleaner element. Check air cleaner element.
Excessive oil consumption. External oil leak. Check drain plug.
Check oil pan for leaks.
Check rear main crankshaft seal for leaks.
Check front cover crankshaft seal for
leaks.
Check front cover for leaks.
Check oil pressure sending unit for leaks.
Check oil filter for leaks.
Check cam cover for leaks.
Internal oil leak. Check valves and seals. (See “Valves” on
page 7-27.)
Check PCV valve. (See “PCV Valve” on
page 7-4.)
Check piston rings/cylinder compression.
(See “Cylinder Compression Test” on
page 5-6.)
Check cylinder head and gasket. (See
“Cylinder Head” on page 7-24.)
Low oil pressure. Incorrect engine oil. Change engine oil. (See “Change Engine
Oil” on page 3-2.)
Low oil level. Check oil level. (See “Engine Oil Level” on
page 3-2.)
Restricted oil filter. Change oil filter. (See “Oil Filter” on
page 3-2.)
Faulty oil pump relief valve. Check oil pump relief valve. (See “Oil
Pump” on page 7-33.)
Faulty oil pump. Replace oil pump. (See “Oil Pump” on
page 7-33.)
Restriction in lubrication system. Check/clean lubrication system. (See
“Lubrication System” on page 4-11.)
Condition Probable Cause Remedy
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