Lack of Power/Sluggish/Spongy/Stumble

SYMPTOM DESCRIPTION:
Engine delivers less than expected power. Little or no increase in speed, when accelerator is pushed down part way.




SYSTEM OR COMPONENT TO CHECK ACTION

COMPUTER INPUTS/OUTPUTS CHECK: ^ ECM/PCM grounds for being clean,
tight, and in their proper location.




FUEL CHECK: ^ FUEL PRESSURE: use CHART A-6 in
DIAGNOSTIC CHARTS/A-CHARTS
^ CONTAMINATED FUEL
^ RESTRICTED FUEL FILTER





IGNITION CHECK: ^ Proper ignition voltage output with
spark tester J 26792 or equivalent ( ST-125).
^ ELECTRONIC SPARK TIMING (EST) operation.
^ IGNITION TIMING.





EMISSIONS CHECK: ^ EGR SYSTEM: Valve operation.






EXHAUST CHECK: ^ RESTRICTION.
1. With engine at normal operating temperature,
connect a vacuum gauge to any convenient
vacuum port on intake manifold.
2. Run engine at 1000 rpm and record vacuum
reading.
3. Increase rpm slowly to 2500 rpm. Note vacuum
reading at a steady 2500 rpm.
4. If vacuum at 2500 rpm decreases more than
3" Hg, from reading at 1000 rpm, the exhaust
system should be inspected for restrictions.
5. Disconnect exhaust pipe from engine and repeat
Step 3 & 4. If vacuum still drops more than
3" Hg, with exhaust disconnected, check for
exhaust manifold restriction and valve timing.






ENGINE/TRANSMISSION CHECK: ^ GENERATOR OUTPUT VOLTAGE. Repair, if less
than 9 or more than 16 volts.
^ A/C operation.
^ ENGINE COMPRESSION.
^ ENGINE VALVE TIMING.
^ ENGINE CAMSHAFT for wear and proper
application.
^ TORQUE CONVERTER CLUTCH (TCC) operation.
^ TRANSMISSION SHIFT POINTS.