GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

DEFINITION: The engine delivers less than expected power. There is little or no increase in speed when the accelerator pedal is partially applied.

1

Were the Preliminary Checks performed?

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Go to Step 2

Go to Symptoms - Engine Controls

2

  1. Verify the customer's complaint.
  2. Compare the performance of the customer's vehicle with a similar unit.

Does the problem exist?

--

Go to Step 3

System OK

3

  1. Inspect the air filter for excessive contamination.
  2. Replace the air filter as needed.
  3. Inspect the transaxle shift pattern and downshift operation.

Does the transaxle operate properly?

--

Go to Step 4

Go to Step 5

4

Measure the fuel system pressure.

Is the fuel system pressure within the specified range?

379-393 kPa (55-57 psi)

Go to Step 7

Go to Step 6

5

Repair the transaxle as needed.

Did you complete the repair?

--

System OK

--

6

Repair the fuel system as needed.

Is the repair complete?

--

System OK

--

7

Inspect for a restricted fuel filter or contaminated fuel.

Is a repair necessary?

--

Go to Step 8

Go to Step 9

8

Repair or replace any components as needed.

Did you complete the repair?

--

System OK

--

9

  1. Inspect the ignition system output for all of the cylinders using a spark tester.
  2. Inspect for proper ignition control operation.

Is the ignition system operating properly?

--

Go to Step 10

Go to Step 11

10

  1. With the engine at normal operating temperature, connect a vacuum gage to a vacuum port on the intake manifold.
  2. Operate the engine at 1,000 RPM.
  3. Record the vacuum reading.
  4. Increase the engine speed to 2,500 RPM.
  5. Note the vacuum reading at a steady 2,500 RPM.

Does the vacuum decrease more than the value specified?

10 kPa (1.5 psi)

Go to Step 12

Go to Step 15

11

Repair or replace any ignition system components as needed.

Did you complete the repair?

--

System OK

--

12

Inspect the exhaust system for restrictions and damaged or collapsed pipes.

Is a repair necessary?

--

Go to Step 13

Go to Step 15

13

Repair or replace any components as needed.

Did you complete the repair?

--

System OK

--

14

  1. Inspect the cylinder compression and valve timing.
  2. Inspect the camshaft for excessive wear.

Is a repair necessary?

--

Go to Step 15

Go to Step 16

15

Repair or replace any engine components as needed.

Did you complete the repair?

--

System OK

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16

  1. Inspect the engine control module (ECM) grounds for being clean, tight, and in their proper location.
  2. Inspect the exhaust gas recirculation (EGR) valve for being open or partially open all the time.
  3. Inspect the torque converter clutch (TCC) operation.
  4. Inspect the A/C system operation.
  5. Inspect the generator output.
  6. Repair the generator if the output is not within 12-16 V.

Did you find and correct the condition?

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System OK

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