Lack of Power/Sluggish/Spongy/Stumble
DEFINITION: Engine delivers less than expected power. Little or no increase in speed when the accelerator pedal is pushed down part way.PRELIMINARY CHECKS
^ Refer to Symptoms, Important Preliminary Checks Before Starting. Testing and Inspection
^ Search for bulletins.
^ Check PCM grounds for being clean, tight and in their proper locations.
^ Remove and check air filter element for dirt, or for being restricted. Refer to Air Filter Element/Air Cleaner Assembly and replace as necessary.
FUEL SYSTEM CHECKS
^ Check for low fuel pressure. System Diagnosis - Fuel System
^ Check for restricted fuel filter.System Diagnosis - Fuel System
^ Check for contaminated fuel. Refer to Alcohol Contaminants in-Fuel Testing Procedure. Fuel
^ Check items which can cause an engine to run rich (long term fuel trim near -14%). For a Rich condition, refer to DTC P0132 HO2S Circuit High Voltage Bank 1 Sensor 1 and DTC P0152 HO2S Circuit High Voltage Bank 2 Sensor 1.
^ Check items that can cause an engine to run lean (long term fuel trim near 22%). For a Lean condition, refer to DTC P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1 and DTC P0151 HO2S Circuit Low Voltage Bank 2 Sensor 1.
SENSOR/SYSTEM
^ Using a scan tool, monitor KS system for excessive spark retard activity. Refer to Knock Sensor.
IGNITION SYSTEM
^ Wetting down the secondary ignition system with water from a spray bottle may help locate damaged or deteriorated components. Look/Listen for arcing or misfiring as water is applied.
^ Check for proper ignition voltage output with spark tester J 26792. System Check - Distributor Ignition (DI)
^ Remove spark plugs and check for the following:
- Wet plugs
- Cracks
- Wear
- Improper gap
- Burnt electrodes
- Heavy deposits
^ An improper spark plug gap will cause a driveability problem. Refer to spark plug gap specification. The spark plug gapping should be done using a wire gauge gap tool (J 41319). Refer to Spark Plug, Replacement. If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs. Refer to DTC P0172 Fuel Trim System Rich Bank 1 or DTC P0175 Fuel Trim System Rich Bank 2 to determine the Rich condition or Engine Mechanical for the oil fouling condition.
^ Check for loose ignition coil ground. System Check - Distributor Ignition (DI)
^ Spark plugs for proper heat range.
^ Check distributor vent system for being restricted or open. System Check - Distributor Vent
ENGINE MECHANICAL
^ Excessive oil in combustion chamber-Leaking valve seals. Refer to Engine.
^ Low cylinder compression. Refer to Engine.
^ For incorrect basic engine parts. Inspect the following:
- Camshaft
- Cylinder heads
- Pistons, etc.
Refer to Engine.
ADDITIONAL CHECKS
^ Check exhaust system for possible restrictions. Check for the following:
- Inspect exhaust system for damaged or collapsed pipes.
- Inspect mufflers for heat distress or possible internal failure.
- For possible plugged Three Way catalytic converters by comparing exhaust system back pressure on each side of engine. Check back pressure by removing Air Injection Reaction (AIR) check valves near exhaust manifolds. Refer to Restricted Exhaust System Check and Exhaust System.
^ Check Torque Converter Clutch (TCC) for proper operation. Refer to Transmission Control Systems.
^ TC system cable adjuster assembly. Loss of performance can result from an improperly adjusted system which could prevent the throttle from attaining WOT. Refer to Anti-Lock Brake System (ABS) and Traction Control System. Also inspect the throttle body and accelerator cables for binding.