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 appropriate TESTS W/CODES article below.

TESTS W/CODES - OBD-I (2.4L) (for Federal emissions)
TESTS W/CODES - OBD-II (2.4L) (for California emissions)
NOTE: Ensure vehicle is at normal operating temperature with all lights, cooling fan and accessories off. Shift transmission into Neutral or Park position.

Insert paper clip or appropriate probe into tachometer connector. See TACHOMETER CONNECTOR LOCATION table. Connect a primary voltage detecting type tachometer to paper clip.
On all except Pickup, connect a jumper wire between data link terminal No. 1 and vehicle ground. See Fig 2. On Pickup, connect a jumper wire between data link connector terminal No. 10 and vehicle ground. See Fig 1.
Connect a jumper wire between ignition timing adjustment connector and vehicle ground. See IGNITION TIMING ADJUSTMENT CONNECTOR LOCATION table under IGNITION TIMING.
Start and run engine at idle. Check basic idle speed. See IDLE SPEED SPECIFICATIONS table. If idle speed is not within specification, turn engine speed adjusting screw until correct engine speed is obtained. See Fig 3. Access to speed adjusting screw is obtained by removing rubber plug on throttle body.
If idle speed cannot be lowered by turning engine speed adjusting screw, determine if fixed speed adjusting screw (stop screw contacting throttle lever) has been adjusted. See FIXED SPEED ADJUSTING SCREW for procedure.

After all adjustments are verified to be 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

Expo & Summit Wagon

1-Pin

⁽¹⁾

Galant

1-Pin

⁽²⁾

Pickup

1-Pin

⁽³⁾

⁽¹⁾	On main harness, on firewall below Vehicle Identification Plate.

⁽²⁾	On DOHC, 1-pin Blue connector is attached to main harness on center of firewall. On SOHC, disconnect noise condenser connector at distributor and probe female side.

⁽³⁾	On main harness, on firewall to left of Vehicle Identification Plate.

IDLE SPEED SPECIFICATIONS

Application	Curb Idle	Basic Idle
Expo & Summit Wagon	650-850	700-800
Galant
SOHC	650-850	700-800
DOHC	700-900	750-850
Pickup	650-850	700-800

Fig 1: Locating Data Link Connector (Pickup)

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA

Fig 2: Locating Data Link Connector (Except Pickup)

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA

Fig 3: Adjusting Idle Speed (All Models)

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA