GM Service Manual Online
For 1990-2009 cars only

Lack of Power, Sluggish or Spongy Symptom

Step

Action

Value(s)

Yes

No

Definition: The engine delivers less than the expected power. There is little or no increase in the speed when the accelerator pedal is pushed down part way.

1

Did you perform the On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to the Powertrain On Board Diagnostic (OBD) System Check

2

  1. Perform a bulletin search.
  2. If a bulletin that addresses the symptom is present, correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

--

Go to Step 17

Go to Step 3

3

Did you perform a visual/physical check?

--

Go to Step 4

Go to Symptoms for the Visual /Physical Check

4

  1. Remove and check the air filter element for dirt or for a restriction.
  2. Replace the air filter element if necessary.

Was a repair required?

--

Go to Step 17

Go to Step 5

5

Check the Intake Plenum Switchover Valve and the Intake Resonance Switchover Valve for a proper operation. Refer to DTC P1112 Intake Plenum Switchover Solenoid Control Circuit and DTC P1113 Intake Resonance Switchover Solenoid Control Circuit .

Was a problem found and corrected?

--

Go to Step 17

Go to Step 6

6

  1. Check for low fuel pressure. Refer to Fuel System Diagnosis .
  2. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 7

7

  1. Use a J 39383-A in order to check for water or alcohol contaminated fuel.
  2. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 8

8

  1. Use a scan tool in order to monitor the Knock Retard for an excessive spark retard activity.
  2. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 9

9

  1. Check for a proper ignition coil output voltage with spark tester J 26792 (ST 125) by performing the following procedure:
  2. 1.1. Clip the spark tester J 26792 to engine ground.
    1.2. Connect one end of a spark plug wire to the spark tester J 26792 . Leave the other end of the spark plug wire connected to the coil that is being tested.
    1.3. Disconnect the spark plug wire from the other spark plug on the same coil being tested. Ground the wire.
    1.4. Crank the engine while observing the spark tester J 26792 . Look for a blue spark.
    1.5. Repeat the above steps for each coil.
  3. If an adequate spark is not present at all of the coils, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 10

10

  1. Remove the spark plugs. Check for the following conditions:
  2. • Wet plugs
    • Cracks
    • Excessive wear
    • An improper gap
    • Burned electrodes
    • Carbon tracking on the insulator
    • Heavy deposits. Refer to Ignition System Check .

    Notice: Determine the cause of the oil or gas fouled spark plugs in order to avoid damage to the new spark plugs.

  3. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 11

11

  1. Check the ignition coils for cracks or carbon tracking.
  2. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 12

12

  1. Check the ECMPCM grounds for being clean, tight and in the proper locations.
  2. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 13

13

  1. Check the exhaust system for a possible restriction:
  2. • Inspect the exhaust system for any damaged or collapsed pipes.
    • Inspect the muffler for heat distress or a possible internal failure.
    • Check for a possible plugged catalytic converter by checking the exhaust system back pressure. Refer to Restricted Exhaust System Check
  3. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 14

14

  1. Check the Torque Converter Clutch (TCC) for a proper operation. Refer to Transmission Diagnosis
  2. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 15

15

  1. Check for the following Engine Mechanical problems. Refer to Engine Mechanical:
  2. • Low compression
    • Sticking valves
    • A hydraulic valve lifter problem
    • Leaking cylinder head gaskets
    • Worn or incorrect camshaft
    • Incorrect cam timing
    • A damaged timing belt
  3. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 16

16

  1. Review all of the diagnostic procedures within this table.
  2. When all of the procedures have been completed and no malfunctions are present, review/inspect the following items:
  3. • The scan tool data
    • The Freeze Frame data
    • All of the connections within a suspected circuit and/or system
  4. If a problem is present, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 3

17

Operate the vehicle under the same conditions (as closely as possible) as when the original symptom occurred.

Is the original symptom still present?

--

Go to Step 3

The repair is complete. If another driveability symptom exists, refer to Symptoms .