GM Service Manual Online
For 1990-2009 cars only
Table 1: Hard Start
Table 2: Lack of Power, Sluggishness, or Sponginess
Table 3: Rough, Unstable, or Incorrect Idle and Stalling
Table 4: Hesitation, Sag, Stumble
Table 5: Surges/Chuggles
Table 6: Detonation/Spark Knock
Table 7: Engine Overheating
Table 8: Poor Fuel Economy

Hard Start

Checks

Actions

Malfunction of Ignition System

  • Faulty fuse

Replace the fuse.

  • Faulty spark plug

Clean and adjust the plug gap or replace.

  • Electric leakage at the high tension cable

Replace the cable.

  • Poor connection of the high tension cable or lead wires

Replace the cable or wires.

  • Worn distributor cap or accumulated carbon in the distributor cap

Replace or clean the distributor cap.

  • Damaged distributor rotor or cap

Replace the rotor or the cap.

  • Improper ignition timing

Adjust the ignition timing.

  • Faulty ignition coil

Replace the ignition coil.

Malfunction of Fuel System

  • Lock of fuel in the fuel tank

Feed the fuel.

  • Dirty or clogged fuel filter

Replace the filter.

  • Clogged fuel pipe

Clean the fuel pipe.

  • Malfunction of the fuel pump

Replace the fuel pump.

  • Malfunction of the fuel injector

Replace the injector.

  • The foreign material in the fuel tank

Clean the fuel tank.

Decline of Compression Pressure

  • Poor tightening spark plug

Tighten to the specified torque. Refer to Fastener Tightening Specifications

  • Cracked cylinder head gasket

Replace the gasket.

  • Inadequate valve clearance

Adjust the clearance.

  • Leakage of the valve clearance

Repair the valve.

  • Interference of the valve stem

Replace the valve or the valve guide.

  • Low elasticity or damage of the valve spring

Replace the valve spring.

  • Abnormal interference of pistons and cylinders

Replace the piston ring.

  • Excessive wear of pistons, rings, or cylinders

Replace the ring or the piston and boring, or replace the cylinder.

Others

  • Broken timing belt

Replace the belt.

  • Malfunction of positive crankcase ventilation (PCV) valve

Check and replace the PCV valve if needed.

  • Loosening, damage, or leakage of the vacuum hose

Connect the hose correctly or replace it.

  • Leakage of the intake system

Replace the intake system.

Lack of Power, Sluggishness, or Sponginess

Checks

Actions

Decline of Compression Pressure

Refer to Hard Start in Engine Controls - 0.8L.

Malfunction of Ignition System

  • Improper ignition timing

Adjust the ignition timing.

  • Faulty spark plug

Adjust or replace the spark plug.

  • Malfunction of the distributor

Repair or replace the distributor. Check the rotor.

  • Electric leakage or poor connection of the high tension cable

Connect the cable correctly or replace it.

Malfunction of Fuel System

  • Clogged fuel pipe

Clean the pipe.

  • Clogged or contaminated fuel filter

Replace the filter.

Others

  • Clogged exhaust system

Check and repair the system.

  • Clogged or contaminated air cleaner element

Clean or replace the air cleaner element.

  • Leak of the intake manifold gasket

Replace the gasket.

  • Dragging brakes

Repair or replace the brakes.

  • Slipping clutch

Adjust or replace the clutch.

Rough, Unstable, or Incorrect Idle and Stalling

Checks

Actions

Decline of Compression Pressure

Refer to Hard Start in Engine Controls - 0.8L.

Malfunction of Fuel System

  • Clogged fuel pipe

Clean the pipe.

  • Clogged or contaminated fuel filter

Replace the filter.

  • Malfunction of the fuel pressure regulator

Replace the regulator.

Malfunction of Ignition System

  • Malfunction of the spark plug

Adjust or replace the spark plug.

  • Electric leakage or poor connection of the high tension cable

Connect the cable correctly or replace it.

  • Worn distributor cap terminal or accumulated carbon in the distributor cap

Replace or clean the distributor cap.

  • Loosening or damage of the distributor rotor or cap

Replace the rotor or cap.

  • Poor ignition timing

Adjust the ignition timing.

  • Malfunction of the ignition coil

Replace the ignition coil.

Others

  • Clogged or contaminated air cleaner element

Clean or replace the air cleaner element.

  • Leak of the intake manifold gasket

Replace the gasket.

  • Malfunction of positive crankcase ventilation (PCV) valve

Check the valve or replace it if needed.

  • Poor connection or damage or leakage of the vacuum hose

Connect the hose correctly or replace it.

Hesitation, Sag, Stumble

Checks

Actions

Decline of Compression Pressure

Refer to Hard Start in Engine Controls - 0.8L.

Malfunction of Ignition System

  • Poor ignition timing

Adjust the ignition timing.

  • Poor spark plug or poor adjustment of the plug gap

Replace the plug or adjust the gap.

  • Electric leakage or poor connection of the high tension cable

Connect the cable correctly or replace it.

Others

  • Malfunction of the air cleaner system

Clean or replace the air cleaner system.

  • Leak of the intake manifold gasket

Replace the gasket.

Surges/Chuggles

Checks

Actions

Decline of Compression Pressure

Refer to Hard Start in Engine Controls - 0.8L.

Malfunction of Fuel System

  • Clogged fuel pipe

Clean the pipe.

  • Clogged or contaminated fuel filter

Replace the filter.

  • Malfunction of the fuel pressure regulator

Replace the fuel pressure regulator.

Malfunction of Ignition System

  • Malfunction of the spark plug

Adjust or replace the spark plug.

  • Electric leakage or poor connection of the high tension cable

Connect the cable correctly or replace it.

  • Worn distributor cap terminal or accumulated carbon in the distributor cap

Clean or replace the distributor cap.

  • Loosening or damage of the distributor rotor or the cap

Replace the distributor rotor or the cap.

  • Poor ignition timing

Adjust the ignition timing.

Others

  • Leak of the intake manifold gasket

Clean or replace the gasket.

  • Leakage of the vacuum hose

Connect the hose correctly or replace it.

Detonation/Spark Knock

Checks

Actions

Overheated Engine

Refer to Engine Overheating .

Malfunction of Ignition System

  • Abnormal spark plug

Replace the spark plug.

  • Poor ignition timing

Adjust the ignition timing.

  • Electric leakage or poor connection of the high tension cable

Connect the cable correctly or replace it.

Malfunction of Fuel System

  • Clogged or contaminated fuel filter and fuel pipe

Clean or replace the fuel filter and the fuel pipe.

Others

  • Leak of the intake manifold gasket

Replace the gasket.

  • Excessive carbon deposit due to abnormal combustion

Remove the carbon.

Engine Overheating

Checks

Actions

Malfunction of Cooling System

  • Lack of coolant

Refill the coolant.

  • Malfunction of the thermostat

Replace the thermostat.

  • Malfunction of the cooling fan

Check or replace the cooling fan.

  • Poor water pump performance

Replace the pump.

  • Clogged or leaky radiator

Clean, repair, or replace the radiator.

Malfunction of Lubrication System

  • Poor engine oil

Replace the engine oil with the specified one.

  • Blocking oil filter or strainer

Clean or replace the oil filter or the strainer.

  • Lack of engine oil

Refill the oil.

  • Poor oil pump performance

Replace or repair the pump.

  • Leakage of oil

Repair the leak.

Other

  • Damaged cylinder head gasket

Replace the gasket.

Poor Fuel Economy

Checks

Actions

Decline of Compression Pressure

Refer to Hard Start in Engine Controls - 0.8L.

Malfunction of Fuel System

  • Leakage of the fuel tank or the fuel pipe

Repair or replace the fuel tank or the fuel pipe.

Malfunction of Ignition System

  • Improper ignition timing

Adjust the ignition timing.

  • Abnormal spark plug - Excessive carbon deposit, inadequate gap, burnt electrode

Replace the plug.

  • Electric leakage or poor connection of the high tension cable

Connect the cable normally or replace it.

Malfunction of Cooling System

  • Malfunction of the thermostat

Replace the thermostat.

Others

  • Improperly installed valve

Repair or replace the valve.

  • Slipping clutch

Repair or replace the clutch.

  • Low pressure of tires

Adjust the pressure of the tires.