Home ReviewsRefund
Home/Cadillac/DeVille Concours/Cadillac DeVille Concours I final (1999-1999)/Repair manual/Adjustments/Engine Adjustments
Contents Section: Adjustments All sections

Engine Adjustments Cadillac DeVille Concours I final

Adjustments ~823 words

ENGINE MECHANICAL

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

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 before disconnecting battery.

VALVE CLEARANCE

Note. All models use hydraulic lifters. Adjustments are not required.

IGNITION TIMING

Note. All engines are equipped with C 3 I, DIS or IDI ignition systems. Timing on these systems is not adjustable.

IDLE SPEED & MIXTURE

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

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

4-CYLINDER IDLE SPEED

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

1.9L

  1. Warm engine to normal operating temperature. Turn ignition off. Ensure all accessories are off. Connect IAC Tool (SA9195E) to IAC valve electrical connector. Move lever on tool downward to completely seat IAC valve pintle. Insert IAC Air Plug (SA9106E) in throttle body assembly. Connect scan tool to Data Link Connector (DLC).
  2. Start engine and check idle speed. Idle speed should be between zero (stall) and 700 RPM. If idle speed is not as specified, check for vacuum leaks or binding throttle blade. Clean throttle bore if necessary.
  3. If idle speed is greater than 700 RPM after repairs, replace throttle body. DO NOT adjust minimum idle speed screw. Turn engine off. Remove IAC tool and reconnect IAC valve electrical connector. Check Throttle Position (TP) sensor voltage. See «THROTTLE POSITION (TP) SENSOR»(/cadillac/deville-concours/i-final-1999-1999/remont/adjustments/#engine-adjustments__throttle-position-tp-sensor) .
  4. Remove IAC air plug. Start engine and verify proper idle speed. If proper idle speed cannot be obtained, see appropriate SELF-DIAGNOSTICS article.

2.2L & 2.4L

  1. Idle speed is PCM-controlled. Resetting of IAC valve pintle is the only adjustment that can be performed. To reset IAC valve pintle position, turn ignition on.
  2. Turn ignition off for 10 seconds. Start engine and check for proper idle operation. Repeat procedure if proper idle operation is not obtained.

V6 IDLE SPEED

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

3.1L, 3.4L, 3.5L, 3.8L & 4.0L

  1. Idle speed is PCM-controlled. Resetting of IAC valve pintle is the only adjustment that can be performed. To reset IAC valve pintle position, turn ignition on.
  2. Turn ignition off for 10 seconds. Start engine and check for proper idle operation. Repeat procedure if proper idle operation is not obtained.

V8 IDLE SPEED (EXCEPT CORVETTE)

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

Automatic Transmission

Resetting of IAC valve pintle is the only adjustment that can be performed. To reset IAC valve pintle position, turn off A/C controls. Apply parking brake and block drive wheels. Start engine and allow it to reach normal operating temperature. Place gear selector in Drive. Allow engine to idle for 5 minutes. Place gear selector in Park. Allow engine to idle for an additional 5 minutes. Turn engine off for 30 seconds.

Manual Transmission

Resetting of IAC valve pintle is the only adjustment that can be performed. To reset IAC valve pintle position, turn off A/C controls. Apply parking brake and block drive wheels. Place gear selector in Neutral. Start engine and allow it to reach normal operating temperature. Allow engine to idle for 5 minutes. Turn engine off for 30 seconds.

THROTTLE POSITION (TP) SENSOR

Note. Ensure TP sensor voltage is as specified. See TP SENSOR VOLTAGE table. TP sensor is not adjustable. For further testing procedures, see appropriate SELF-DIAGNOSTICS article.

Note. On Corvette, throttle control is electronic with no mechanical link from engine to accelerator pedal. The PCM and Throttle Actuator Control (TAC) module monitor the position of accelerator pedal based on signals from a nonadjustable Accelerator Pedal Position (APP) sensor. The APP is mounted above the accelerator pedal.

Application(1) Volts
1.9L0.2-0.6 To 4.5-4.9
2.2L & 2.4L0.35-4.65
3.0L0.3-0.9 To 4.0-5.0
3.1L, 3.5L, 3.8L, 4.0L & 4.6L(2)
5.7L
Camaro & Firebird(2)
Corvette
Sensor No. 1(3)
Sensor No. 2(4)
(1) Voltage range is from idle position to wide open throttle position. (2) Voltage range is less than one volt at closed throttle to greater than 4 volts at wide open throttle. (3) Voltage range is less than one volt at closed throttle to 3.5 volts at wide open throttle. (4) Voltage range is 3.8 volts at closed throttle to less than one volt at wide open throttle.
(1)Voltage range is from idle position to wide open throttle position.
(2)Voltage range is less than one volt at closed throttle to greater than 4 volts at wide open throttle.
(3)Voltage range is less than one volt at closed throttle to 3.5 volts at wide open throttle.
(4)Voltage range is 3.8 volts at closed throttle to less than one volt at wide open throttle.

TP SENSOR VOLTAGE

TP SENSOR LEARN (4.0L & 4.6L)

Note. Ensure accelerator and brake pedals are free from any obstructions while performing TP sensor learn procedure. PCM will not perform learn function with accelerator pedal or brake pedal obstructions.

  1. If a new TP sensor, throttle body or PCM is installed, PCM must learn new TP sensor offset. This procedure is necessary since TP sensor is not adjustable and may be produced by more than one manufacturer, causing varying tolerances during minimum air adjustment.
  2. High idle at closed throttle or a stall condition may occur if PCM maintains an improper TP sensor offset. To perform TP sensor learn, turn ignition on, leaving engine off. Wait 30 seconds, then turn ignition switch to LOCK position. Wait an additional 30 seconds and repeat.