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Engine Controls - Adjustments Buick Century V

Adjustments ~511 words

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. Adjustments are not required.

IGNITION TIMING

Note. Procedures for timing adjustment are for engines equipped with HEI-EST distributors only. Other engines are equipped with C(3)I, DIS, IDI or Opti-Spark ignition system. Timing on these systems is not adjustable.

IDLE SPEED & MIXTURE

Note. Idle mixture is controlled by Engine Control Module (ECM) or Powertrain Control Module (PCM). Adjustment is not possible.

CAUTIONWhen battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION section before disconnecting battery.

4-CYLINDER IDLE SPEED

Note. Idle speed is controlled by ECM or PCM and is not adjustable. Slight fluctuations in idle speed are considered normal. Start and run engine for at least 7 minutes to establish ECM or PCM control of idle.

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

  1. Idle speed is ECM/PCM-controlled. Resetting of IAC valve pintle is the only adjustment that can be performed. To reset IAC valve pintle position, turn ignition off.
  2. Disconnect negative battery terminal for 10 seconds to clear ECM/PCM memory. Reconnect negative battery terminal. Turn ignition on for 2 seconds, then off for 10 seconds. Start engine, and check for proper idle operation. Repeat step 1) if proper idle operation is not obtained.

4-CYLINDER IDLE MIXTURE

Note. Idle mixture is controlled by Electronic Control Module (ECM) or Powertrain Control Module (PCM). Adjustment is not required or possible.

V6 IDLE SPEED

Note. Idle speed is controlled by ECM or PCM and is not adjustable. Slight fluctuations in idle speed are considered normal. Start and run engine for at least 7 minutes to establish ECM or PCM control of idle.

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

  1. Idle speed is ECM/PCM-controlled. Resetting of IAC valve pintle is the only adjustment that can be performed. A Tech-1 scan tester is required to reset IAC valve pintle position. To reset IAC valve pintle position, place transmission in Park or Neutral.
  2. Ensure battery power is present. Install Tech-1 scan tester. Select IAC SYSTEM on Tech-1 scan tester. From MISC TEST mode, select IDLE LEARN. Proceed with IDLE LEARN functions as directed. ECM/PCM memory will be updated with correct IAC valve pintle position.

V6 IDLE MIXTURE

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

4-CYLINDER THROTTLE POSITION SENSOR

Note. TP sensor is not adjustable. For further testing procedures, refer to TESTS W/CODES - 2.2L article in the ENGINE PERFORMANCE section, or SYSTEM/COMPONENT TESTS - 2.2L article in the ENGINE PERFORMANCE section.

V6 THROTTLE POSITION SENSOR

Note. TP sensor is not adjustable. For further testing procedures, refer to TESTS W/CODES - 3.1L , or SYSTEM/COMPONENT TESTS - 3.1L in the ENGINE PERFORMANCE section.

Application(1) Volts
2.2L(2) .60-4.80
3.1L(2) .20-4.00
(1) Voltage range is from idle position to wide open throttle position. (2) TP sensor is not adjustable.
(1)Voltage range is from idle position to wide open throttle position.
(2)TP sensor is not adjustable.

TP SENSOR ADJUSTMENT VOLTAGE