For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
DEFINITION: Momentary lack of response as the accelerator is pushed down. Can occur at any vehicle speed. Usually most pronounced when first trying to make the vehicle move, as from a stop sign. May cause the engine to stall if severe enough.
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | 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 found, correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

--

Go to Step 21

Go to Step 3

3 | Was visual/physical check performed? | -- | Go to Step 4 | Go to Visual/Physical Checks
4 |

1. Start the engine.
2. Observe the HO2S Bn1 Sen 1 and HO2S Bn2 Sen 1 voltage display on the scan tool while modulating the throttle.
3. If the HO2S voltage does not respond quickly to changes in throttle position, check for a contaminated HO2S. HO2S. Refer to

   Notice: Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream in order to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a white powdery coating. Silicon contamination causes a high but false HO2S signal voltage (rich exhaust indication). The control module will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor.

   .

Was a problem found?

--

Go to Step 21

Go to Step 5

5 |

1. Check fuel pressure. Refer to Fuel System Pressure Test .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 21

Go to Step 6

6 |

1. Turn ON the ignition switch.
2. Observe TP angle display on the scan tool while slowly increasing throttle pedal.

Does the TP angle display steadily increase from 0% at closed throttle to 100% at WOT?

--

Go to Step 7

Go to Step 20

7 | Monitor Long Term Fuel Trim on the scan tool. Is Long Term Fuel Trim significantly in the negative range (Rich condition)? | -- | Go to Step 8 | Go to Step 9
8 |

1. Check items that can cause the engine to run rich. Refer to Diagnostic Aids in DTC P0172 Fuel Trim System Rich Bank 1 .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 21

--

9 |

1. Check items that can cause the engine to run lean. Refer to Diagnostic Aids in DTC P0171 Fuel Trim System Lean Bank 1 .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 21

Go to Step 10

10 |

1. Check for proper ignition coil output voltage with a J 26792 spark tester:

• | Clip the spark tester to engine ground.

• | Connect one end of a spark plug wire to the spark tester; connect the other end of the spark plug wire to the coil being tested.

• | Connect one end of another spark plug wire to the other coil tower; connect the other end of the spark plug wire to ground.

• | Crank the engine while observing the spark tester; a crisp blue spark should be observed.

• | Repeat the above steps for each coil.

2. If adequate spark is not present at all coils, replace affected coil(s) as necessary. Refer to Ignition Control Module Replacement .

Was a problem found?

--

Go to Step 21

Go to Step 11

11 |

1. Check for loose ignition control module ground. Refer to Ground Distribution in Electrical Diagnosis.
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 21

Go to Step 12

12 |

1. Visually/Physically inspect the secondary ignition wires Check for the following conditions:

• | Check all ignition wire resistances; should be less than the specified value.

• | Ignition wires for cross firing.

• | Ignition wires arcing to ground.

• | Ignition wires for improper routing.

Important:: Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem Ignition components will arc to ground when a secondary component is faulty.

2. If a problem is found, repair as necessary. Refer to On-Vehicle Service in Ignition System.

Was a problem found?

30K ohms (30,000 ohms)

Go to Step 21

Go to Step 13

13 |

1. Inspect the ignition coils for cracks or carbon tracking.
2. If a problem is found, replace affected coil(s) as necessary. Refer to Ignition Control Module Replacement .

Was a problem found?

--

Go to Step 21

Go to Step 14

14 |

1. Check ignition coil secondary resistance.
2. Replace any coil(s) which are not within the specified values. Refer to Ignition Control Module Replacement .

Was a problem found?

5K-8K ohms

(5000-8000 ohms)

Go to Step 21

Go to Step 15

15 |

1. Remove spark plugs and check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits.
2. If a problem is found, repair as necessary. Refer to On-Vehicle Service in Ignition System.

Was a problem found?

--

Go to Step 21

Go to Step 16

16 |

1. Check PCM grounds for being clean, tight and in the proper locations. Refer to Ground Distribution in Electrical Diagnosis.
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 21

Go to Step 17

17 |

1. Check MAF sensor connections.
2. If a problem is found, replace faulty terminals as necessary. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

--

Go to Step 21

Go to Step 18

18 |

1. Visually/physically check vacuum hoses for splits, kinks, and proper connections and routing. Refer to Emission Hose Routing Diagram .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 21

Go to Step 19

19 |

1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no malfunctions have been found, review/inspect the following:

• | Visual/physical inspection. Refer to Visual/Physical Checks .

• | Scan tool data. Refer to Engine Scan Tool Data List .

• | Freeze Frame data/Failure Records data.

• | All electrical connections within a suspected circuit and/or system.

• | If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 21

Review technical bulletins

20 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Is action complete? | -- | Go to Step 21 | --
21 | Operate the vehicle to duplicate conditions present when the original symptom was noted. Is symptom still present? | -- | Go to Step 3 | System OK