Symptoms. Oldsmobile Shelby Series 1 1999

For 1990-2009 cars

### Important Preliminary Checks Before Starting

Perform the Powertrain On Board Diagnostic (OBD) System Check before using the symptom tables, and verify that all of the following conditions are true:

• | The powertrain control module (PCM) and the malfunction indicator lamp (MIL) are operating correctly.

• | There are no DTCs stored.

• | The engine coolant temperature is not above 132°C (270°F).

| This condition causes the PCM to operate in Engine Coolant Over Temperature/Fuel Disabled Mode. While in Engine Coolant Over Temperature/Fuel Disabled Mode, the PCM turns the fuel off to 4 cylinders at a time in order to keep the engine temperatures from reaching damaging levels. The system perceives Engine Coolant Over Temperature as a lack of power, a miss, or a rough idle. If the vehicle is operating in Engine Coolant Over Temperature/Fuel Disabled Mode, diagnosis the system.

• | The scan tool data is within the normal operating range. Refer to Engine Scan Tool Data List .

• | Verify the customer concern and locate the correct symptom in the table of contents. Inspect the items indicated under that symptom.

• | Several of the symptom procedures ask for a Careful Visual/Physical Check. This step is extremely important, and can lead to correcting a problem without further checks and can save valuable time.

• | If the intermittent condition exists as a start and then a stall, inspect for any DTCs relating to the theft deterrent system. Verify the proper installation of electrical options such as lights, cellular phones, etc.

### Visual/Physical Check

Several of the symptom procedures ask for a Careful Visual/Physical Check. This step is extremely important, and can lead to correcting a problem without further checks and can save valuable time. This check includes the inspection of the following circuits and components:

• | The PCM grounds for being clean, tight, and in their proper location

• | The engine dress cover ground strap

• | The vacuum hoses for splits, kinks, and proper connections, as shown on the Vehicle Emission Control Information label -- Check thoroughly for any type of leak or restriction.

• | The mass air flow (MAF) sensor installation. -- The arrows on the plastic portion of the sensor must point toward the engine.

• | The air intake ducts for being collapsed or for having damaged areas

• | Air leaks at the throttle body mounting area, the MAF sensor, and the intake manifold sealing surfaces

• | The ignition wires for cracking, for hardness, for proper routing and for carbon tracking

• | The engine harness wiring and terminals for proper connections, pinches, or cuts

### Intermittent

Important: Check for improper installation of electrical components if an intermittent condition exists. Inspect for aftermarket theft deterrent devices, for lights, and for cellular phones. Ensure that no aftermarket equipment is connected to the Class 2 circuit. If you cannot locate an intermittent condition, a cellular phone signal communication may cause the condition.

Important: The problem may or may not turn ON the MIL or store a DTC. DO NOT use the diagnostic trouble code (DTC) tables for intermittent problems. The fault must be present in order to locate the problem.

Poor electrical connections or improper wiring cause most intermittent problems. Perform a thorough visual and physical check for the following conditions:

• | Poor mating of the connector halves or a terminal not fully seated or backed out in the connector body -- Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

• | An improperly formed or damaged terminal -- Refer to Connector Repairs in Wiring Systems.

• | Reform or replace the connector terminals in the problem circuit in order to insure the proper contact tension. Refer to Connector Repairs in Wiring Systems.

• | Poor terminal to wire connection requires removing the terminal from the connector body in order to check.

Road test the vehicle with a DMM connected to the suspected circuit. An abnormal voltage when the malfunction occurs is a good indication that there is a malfunction in the circuit being monitored.

Use a scan tool in order to help detect intermittent conditions. The scan tool has several features that you can use in order to locate an intermittent condition. Use the following features to find intermittent faults:

• | You can trigger the Snapshot feature in order to capture and store engine parameters within the scan tool when the malfunction occurs. You can then review this stored information in order to see what caused the malfunction.

• | A scan tool Freeze Frame buffer or Failure Records buffer can also aid in locating an intermittent condition. Review and capture the information in the Freeze Frame and/or Failure Record that is associated with the intermittent DTC being diagnosed. Drive the vehicle in the conditions that were present when the DTC originally set.

Important: If the intermittent condition exists as a start and then a stall, check for any DTCs relating to the theft deterrent system. Check for improper installation of electrical options such as lights, cellular phones etc.

Any of the following may cause an intermittent MIL with no stored DTC:

• | The ignition coils shorted to ground, arcing at the ignition wires or the spark plugs

• | The PCM grounds -- Refer to PCM wiring diagrams.

• | The ignition control (IC) wires routed too close to the secondary ignition wires, coils, or the generator -- Ensure that all of the circuits from the PCM to the ignition coils have good connections.

• | An open diode across the A/C compressor clutch and other open diodes

1. Use the following tables when diagnosing a symptom concern:

• | Hard Start

• | Surges/Chuggles

• | Lack of Power, Sluggishness, or Sponginess

• | Detonation/Spark Knock

• | Hesitation, Sag, Stumble

• | Cuts Out, Misses

• | Poor Fuel Fill Quality

• | Rough, Unstable, or Incorrect Idle and Stalling

• | Dieseling, Run-On

• | Backfire

• | Restricted Exhaust System Check

2. If the condition cannot be isolated using the appropriate table, refer to Intermittent Conditions for further diagnosis.