Home ReviewsRefund
Home/Mitsubishi/Mirage/Mitsubishi Mirage IV (1991-1995)/Repair manual/Adjustments/Engine Controls - Adjustments
Contents Section: Adjustments All sections

Engine Controls - Adjustments Mitsubishi Mirage IV

Adjustments 4 illustrations ~1135 words

INTRODUCTION

Note. Introduction information not applicable.

ENGINE MECHANICAL

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

VALVE CLEARANCE

Note. Valve adjustment is possible on 1.5L and 1.8L engines only. All other models use hydraulic lash adjusters.

VALVE ADJUSTMENT

CAUTIONDO NOT rotate crankshaft in opposite direction of normal engine rotation.
  1. Ensure engine is at normal operating temperature. Remove all spark plugs and valve cover. Rotate crankshaft clockwise to position cylinder No. 1 at TDC of compression stroke. Adjust intake valves on cylinders No. 1 and 2, and exhaust valves on cylinders No. 1 and 3. See «VALVE CLEARANCE SPECIFICATIONS»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments) table.
  2. Rotate crankshaft 360 degrees to position cylinder No. 4 at TDC of compression stroke. Adjust intake valves on cylinders No. 3 and 4, and exhaust valves on cylinders No. 2 and 4. Install spark plugs and valve cover. VALVE CLEARANCE SPECIFICATIONS Application (1) In. (mm) 1.5L (VIN A) Hot Engine Intake .008 (.20) Exhaust .010 (.25) 1.8L (VIN C) Hot Engine Intake .008 (.20) Exhaust .012 (.30) (1) Adjust valves with engine hot.

IGNITION TIMING

Note. Perform all adjustments with engine at normal operating temperature, cooling fan and accessories off, transmission in Park or Neutral, and front wheels in straight-ahead position.

Note. Adjustment of ignition timing cannot be performed on vehicles equipped with Distributorless Ignition Systems (DIS). If ignition timing is not within specification, see CRANKSHAFT POSITION SENSOR in SYSTEM/COMPONENT TESTS article in this section.

  1. Locate ignition timing adjustment connector. See «IGNITION TIMING ADJUSTMENT CONNECTOR LOCATION»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments) table. Connect jumper wire between ignition timing adjustment connector and ground. Check ignition basic timing.
  2. If ignition basic timing is not within specification, loosen distributor and rotate to adjust timing if necessary. See «IGNITION TIMING SPECIFICATIONS»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments) table. Remove jumper wire from ignition timing adjustment connector. IGNITION TIMING SPECIFICATIONS (Degrees BTDC @ RPM) Application (1) Basic (2) (3) Actual 1.5L 5 @ 650-850 10 @ 650-850 1.8L 3-7 @ 650-850 5 @ 650-850 (1) With ignition timing adjustment connector grounded or vacuum hose (farthest from distributor) disconnected. (2) With ignition timing adjustment connector ungrounded or vacuum hose (farthest from distributor) connected. Ignition timing may fluctuate. (3) If vehicle altitude is more than 2300 ft. above sea level, actual timing may be advanced. NOTE: Ignition timing adjustment connector is either round or oval with protective cover. Connector is either Black or Brown and is secured to harness with colored transparent tape. IGNITION TIMING ADJUSTMENT CONNECTOR LOCATION Application (1) (2) Wire Color Location All Models Black/Blue (3) (1) Remove waterproof female connector (if equipped) for access to wire. (2) Ground connector at wire end for basic timing adjustment. (3) On main wiring harness, near center of firewall.

IDLE SPEED & MIXTURE

Note. Perform adjustments with engine at normal operating temperature, cooling fan and accessories off, transmission in Park or Neutral, and front wheels in straight-ahead position.

CURB (SLOW) IDLE SPEED

Note. Curb idle speed is controlled by Idle Air Control (IAC) motor. Adjustment is usually not necessary. For curb idle speed specifications, see IDLE SPEED SPECIFICATIONS table under BASIC IDLE SPEED.

  1. Check ignition timing and adjust if necessary. See «IGNITION TIMING»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments) . Run engine at 2000-3000 RPM for more than 5 seconds. Allow engine to idle for 2 minutes. Check curb idle speed.
  2. If curb idle speed is not within specification, check IAC system. See «SYSTEM/COMPONENT TESTS»(/mitsubishi/mirage/iv-1991-1995/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article in this section. If IAC system is okay, adjust basic idle speed. See «BASIC IDLE SPEED»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments__basic-idle-speed) .

BASIC IDLE SPEED

Note. ALWAYS check TPS adjustment after adjusting basic idle speed. See THROTTLE POSITION SENSOR (TPS) .

Note. For Data Link Connector (DLC) location, see TESTS W/CODES article in this section.

Note. Ensure vehicle is at normal operating temperature with all lights, cooling fan and accessories off. Shift transmission into Neutral or Park position.

Scheme 1

Scheme 1: BASIC IDLE SPEED
Scheme 1: BASIC IDLE SPEED

Scheme 2

Scheme 2
Scheme 2
  1. Insert paper clip or appropriate probe into tachometer connector. See «TACHOMETER CONNECTOR LOCATION»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments) table. Connect a primary voltage detecting type tachometer to paper clip.
  2. Connect a jumper wire between data link terminal No. 10 and vehicle ground. (Scheme 1) Connect a jumper wire between ignition timing adjustment connector and vehicle ground. See «IGNITION TIMING ADJUSTMENT CONNECTOR LOCATION»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments) table under IGNITION TIMING.
  3. Start and run engine at idle. Check basic idle speed. See «IDLE SPEED SPECIFICATIONS»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments) table. If idle speed is not within specifications, turn engine speed adjusting screw until correct engine speed is obtained. (Scheme 2) Access to speed adjusting screw is obtained by removing rubber plug on throttle body.
  4. If idle speed cannot be lowered by adjusting engine speed adjusting screw, determine if fixed speed adjusting screw (stop screw contacting throttle lever) has been adjusted. See «FIXED SPEED ADJUSTING SCREW»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments__fixed-speed-adjusting-screw) for procedure.
  5. After all adjustments are verified correct, possible cause of incorrect idle speed is deterioration of fast idle air control motor. Throttle valve must be replaced to correct symptom. Disconnect jumper wires and recheck idle speed. TACHOMETER CONNECTOR LOCATION Application Type Location All Models 1-Pin (1) (1) Next to ignition timing adjustment connector. IDLE SPEED SPECIFICATIONS Application Curb Idle Basic Idle 1.5L 650-850 650-850

FIXED SPEED ADJUSTING SCREW

Note. Fixed Speed Adjusting Screw (FSAS) is preset by manufacturer and usually does not require adjustment. Only adjust FSAS if other adjustment procedures require it, or if manufacturer's original setting has been changed.

Scheme 3

Scheme 3: FIXED SPEED ADJUSTING SCREW
Scheme 3: FIXED SPEED ADJUSTING SCREW

IDLE MIXTURE

Note. Idle mixture is computer controlled on fuel injected engines and is nonadjustable. CO level specifications are not available from manufacturer.

TPS ADJUSTMENT

Note. Ensure basic idle speed is set to specification before adjusting TPS. See BASIC IDLE SPEED under IDLE SPEED & MIXTURE. Perform all adjustments with engine at normal operating temperature, front wheels in straight-ahead position, cooling fan and all accessories off, and transmission in Park or Neutral.

Application(1) Volts
Mirage.48-.52
All Others.4-1.0
(1) At idle.
(1)At idle.

TPS SPECIFICATIONS

Scheme 4

Scheme 4
Scheme 4
  1. Disconnect TPS connector. Using external ohmmeter, measure resistance between TPS terminals No. 3 and 4. (Scheme 4) Insert.256" (.65 mm) feeler gauge between fixed speed adjusting screw and throttle lever.
  2. Loosen TPS mounting screws and rotate TPS fully clockwise. Ensure there is continuity between terminals No. 3 and 4. Rotate TPS counterclockwise until there is no continuity and tighten screws. Install Test Harness (MB991348) between TPS and harness connector.
  3. Turn ignition on. Using external voltmeter, measure TPS output voltage between terminals No. 2 and 4. See «TPS SPECIFICATIONS»(/mitsubishi/mirage/iv-1991-1995/remont/adjustments/#engine-controls-adjustments) table. If voltage is not within specification, check harness and sensor. See «SYSTEM/COMPONENT TESTS»(/mitsubishi/mirage/iv-1991-1995/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) article in this section.

IDLE POSITION SWITCH

Note. Idle position switch is preset by manufacturer. Adjustment is usually not necessary. If other procedures require adjustment of idle position switch or if switch setting has been changed, adjust switch as follows.

Idle position switch is incorporated into IAC motor and is automatically adjusted when TPS is adjusted. See TPS ADJUSTMENT .