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.
4-CYLINDER IGNITION TIMING
Note. Procedures for timing adjustment are for engines equipped with HEI-EST distributors only. All other models are equipped with either C(3)I, DIS or IDI ignition system. Timing on these systems is not adjustable.
2.0L (VIN K)
- Set parking brake and block drive wheels. Warm engine to normal operating temperature. Ensure all accessories are off. Ensure SERVICE ENGINE SOON (SES) light is off. Using a jumper, ground ALDL test connector. ALDL test connector is located under driver's side of dash. Start engine. The SES light should flash.
- Connect timing light to No. 1 spark plug wire and record position of timing mark. Move timing light to No. 4 spark plug wire. Check timing and record position of timing mark.
- To obtain average timing, add both timing figures and divide by 2. If timing is not as specified, adjust average timing by turning distributor. See 4-CYLINDER IGNITION TIMING table.
- Remove jumper from ALDL test connector. Check SES light. If SES light stays on, remove Electronic Control Module (ECM) fuse from fuse block or disconnect ECM pigtail at battery for about 10 seconds.
| Application | Man. Trans. | Auto. Trans. |
|---|---|---|
| 2.0L (VIN K) | 8 @ Idle | (1) 8 @ Idle |
| 2.2L (VIN G) | (2) | (2) |
| 2.3L (VIN A & D) | (2) | (2) |
| 2.5L (VIN R & U) | (2) | (2) |
| (1) Set timing at less than 800 RPM with transmission in Park. (2) Not adjustable. For specifications, see vehicle emission control label. | ||
| (1) | Set timing at less than 800 RPM with transmission in Park. |
| (2) | Not adjustable. For specifications, see vehicle emission control label. |
4-CYLINDER IGNITION TIMING
IDLE MIXTURE
Note. Idle mixture is controlled by the Electronic Control Module (ECM). Adjustment is not possible.
4-CYLINDER IDLE SPEED
Note. Idle speed is controlled by ECM. Slight fluctuations in idle speed are considered normal. Start and run engine for at least 7 minutes to re-establish ECM control of idle.
Note. Incorrect idle speeds are normally caused by dirty throttle plate or vacuum leaks. Ensure all vacuum components are functioning properly.
2.0L (VIN K) & 2.5L (VIN R & U)
- Ensure engine is at normal operating temperature. Ground ALDL test connector located under driver's side dash. With ignition on and engine off, wait 30 seconds for Idle Air Control (IAC) valve to seat in throttle body.
- Disconnect IAC valve electrical connector. Connect tachometer or "Scan" tester to monitor engine RPM. Disconnect ground from ALDL test connector.
- With transaxle in Park or Neutral, start engine and allow engine RPM to stabilize. Ensure all accessories are turned off. Observe idle speed. See MINIMUM IDLE SPEED (4 CYLINDERS) table.
- If idle speed is incorrect, remove air cleaner to gain access to throttle body (if necessary). Plug any disconnected hoses. Disconnect throttle cable and kickdown cable (A/T vehicles). Use an awl to pierce cover of minimum idle stop screw. Apply leverage to remove cover.
- Using minimum idle stop screw, adjust engine idle speed to specification. 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.
2.2L (VIN G)
Idle speed is ECM controlled and is not adjustable.
2.3L (VIN A & D)
- Install "Scan" tester to ALDL test connector. Start and run engine to normal operating temperature. Observe IAC counts. See MINIMUM IDLE SPEED (4 CYLINDERS) table.
- If idle speed is 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.
- 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 Application RPM 2.0L (VIN K) 450-650 2.2L (VIN G) (1) 2.3L (VIN A & D) (2) 2.5L (VIN R & U) 550-650 (1) Idle speed is ECM controlled and is not adjustable. (2) Idle RPM should be 15-45 counts on "Scan" tester.
- Press the WARMER button on Electronic Climate Control (EEC) panel. The fuel data center should alternately display E.5.3. and 99, indicating override function has started. The ISC will extend to maximum extend position.
- With ISC at maximum extension, Throttle Position Sensor (TPS) voltage should be 1.15-1.20 volts. If TPS voltage is less than 1.15 volts, go to next step. If TPS voltage is greater than 1.20 volts, go to step 5).
- Adjust ISC plunger out by turning plunger counterclockwise until TPS parameter reads 1.18 volts.
- Adjust ISC plunger in by turning plunger clockwise until TPS parameter reads 1.18 volts.
- Recheck ISC maximum extension setting. Press COOLER button to retract ISC plunger. Wait 5 seconds. Press the WARMER button and read TPS voltage. Adjust ISC plunger again if necessary.
- After all adjustments are made and while still in diagnostic mode, turn ignition off. Allow approximately 20 seconds for ISC motor to retract and perform a TPS learn routine.
- Re-enter diagnostics and repeat step 7). It takes 2 cycles for a successful TPS learn to occur. Remove alternator disable ground wire (Green harness connector plug). Start engine and check for proper ISC motor operation.
4-CYLINDER THROTTLE POSITION SENSOR
Note. TPS is not adjustable. For further testing procedures, refer to appropriate G - TESTS W/ CODES article in this section, or SYSTEM/COMPONENT TESTS article in this section.
See also:
• SYSTEM/COMPONENT TESTS