Engine Controls - Adjustments - v6 Chevrolet Beretta I

ENGINE MECHANICAL

Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.

VALVE CLEARANCE

Note. All models use hydraulic lifters. No adjustments are required.

V6 IGNITION TIMING

Note. Some engines are equipped with a socket for a magnetic probe timing meter, located 9.5 degrees ATDC. DO NOT use this location for setting timing with a conventional timing light.

3.1L (CAMARO & FIREBIRD)

1. Warm engine to normal operating temperature. Disconnect Electronic Spark Timing (EST) connector located on wiring harness near distributor, or ground ALDL test connector using a jumper. ALDL is located under driver's side of dash.
2. Connect timing light to No. 1 spark plug wire. Set timing to specification. See V6 IGNITION TIMING table. Tighten distributor and recheck timing.
3. With engine still running, remove jumper from ALDL test connector. If jumper wire is removed before engine is turned off, trouble code(s) will not be stored. Reconnect EST connector if disconnected.

V6 IGNITION TIMING

IDLE LEARN PROCEDURE (3.1L & 3.4L)

Any time the battery is disconnected, the programmed position of the IAC valve pintle is lost, and replaced with a "default" value. To return the IAC valve pintle to the correct position, perform the following procedure

Note. This procedure, called the "quick-learn" Idle Learn procedure, utilized the capabilities of the Tech 1 "Scan" tool. For the procedure to work properly, the vehicle transaxle must be in Park or Neutral.

1. Restore battery power and place transaxle in Park or Neutral. Connect Tech 1, "Scan" tool. Select "IAC" System," then select "Idle Learn" in the "Misc. Test" mode.
2. Proceed with idle learn as directed.

This procedure allows the ECM memory to be updated with the correct pintle position for the vehicle, and provide a stable idle speed.

IDLE MIXTURE

Note. Idle mixture is controlled by the Electronic Control Module (ECM). Adjustment is not possible.

V6 IDLE SPEED

Note. Incorrect idle speeds are normally caused by dirty throttle plate or vacuum leaks. Ensure all vacuum components are functioning properly.

ALL MODELS

1. Install "Scan" tester to ALDL test connector located under driver's side of dash. Start and run engine to normal operating temperature. Observe Idle Air Control (IAC) counts. See MINIMUM IDLE SPEED (V6) table.
2. If IAC counts are incorrect, use an awl to pierce cover of minimum idle stop screw. Apply leverage to remove cover. Turn idle stop screw out until screw clears linkage. Turn screw in until screw touches linkage. Turn screw in an additional 1 1/2 turns.
3. Turn idle stop screw in to decrease IAC counts. Turn screw out to increase IAC counts. If minimum idle speed correction requires more than 1/2 turn (in or out) of idle stop screw, check for vacuum leaks or dirty throttle plate. Clear any trouble codes.

MINIMUM IDLE SPEED

V6 THROTTLE POSITION SENSOR

Note. Not all TPS are adjustable. For further testing procedures, refer to appropriate G - TESTS W/ CODES article in table above, or refer to SYSTEM/COMPONENT TESTS article in this section.

Throttle Position Sensor (TPS) can be adjusted using "Scan" tester or the following procedure.

1) Ensure engine is at normal operating temperature. Install 3 jumper wires between TPS and TPS wiring harness connector.

2) Turn ignition on with engine off. Connect a DVOM to Dark Blue and Black wire terminals. With throttle at closed position, adjust TPS to obtain specified voltage. See TPS ADJUSTMENT VOLTAGE table.

3) Tighten screws and recheck readings. Turn ignition off. Remove jumper wires and reconnect harness connector to TPS.

TPS ADJUSTMENT VOLTAGE

See also:
• SYSTEM/COMPONENT TESTS