Mitsubishi Montero (1991+). Manual — part 41

ANTI-LOCK BRAKE SAFETY PRECAUTIONS

1991 Mitsubishi Montero

GENERAL INFORMATION

Anti-Lock Brake Safety Precautions

* PLEASE READ THIS FIRST *

This article is intended for general information purposes

only. This information may not apply to all makes and models. If

vehicle is equipped with Anti-Lock Brake System (ABS), refer to

appropriate ANTI-LOCK BRAKE SYSTEM article in the BRAKES section for

description, operation, depressurizing, testing, system bleeding,

trouble shooting and servicing of specific system.

WARNING: Failure to depressurize ABS could lead to physical injury.

ANTI-LOCK BRAKE SAFETY PRECAUTIONS

WARNING: Failure to depressurize ABS could lead to physical injury.

* NEVER open a bleeder valve or loosen a hydraulic line

while ABS is pressurized.

* NEVER disconnect or reconnect any electrical connectors

while ignition is on. Damage to ABS control unit may result.

* DO NOT attempt to bleed hyudarulic system without first

referring to the appropriate ANTI-LOCK BRAKE SYSTEM article

in the BRAKES section.

* Only use specially designed brake hoses/lines on ABS equipped

vehicles.

* DO NOT tap on speed sensor components (sensor, sensor rings).

Sensor rings must be pressed into hubs, NOT hammered into

hubs. Striking these components can cause demagnetization or

a loss of polarization, affecting the accuracy of the speed

signal returning to the ABS control unit.

* DO NOT mix tire sizes. Increasing the width, as long as tires

remain close to the original diameter, is acceptable. Rolling

diameter must be identical for all 4 tires. Some

manufacturers recommend tires of the same brand, style and

type. Failure to follow this precaution may cause inaccurate

wheel speed readings.

* DO NOT contaminate speed sensor components with grease. Only

use recommended coating, when system calls for an

anti-corrosion coating.

* When speed sensor components have been removed, ALWAYS check

sensor-to-ring air gaps when applicable. These specifications

can be found in each appropriate article.

* ONLY use rocommended brake fluids. DO NOT use silicone brake

fluids in an ABS equipped vehicle.

* When instlling transmittion devices (CB’s, telephones, etc.)

on ABS equipped vehicles, DO NOT locate the antenna near the

ABS control unit (or any control unit).

* Disconnect all on-board computers, when using electric

welding equipment.

* DO NOT expose the ABS control unit to prolonged periods of

high heat (185 F/85 C for 2 hours is generally considered a

maximum limit).

F - BASIC TESTING

1991 Mitsubishi Montero

1991 ENGINE PERFORMANCE

Basic Diagnostic Procedures

Chrysler; Colt, Colt 200, Colt Vista, Ram-50, Stealth,

Summit

Mitsubishi; Eclipse, Galant, Mirage, Montero, Pickup, 3000GT

INTRODUCTION

The following diagnostic steps will help prevent overlooking

a simple problem. This is also where to begin diagnosis for a no start

condition. First step in diagnosing any driveability problem is

verifying customer’s complaint with a test drive under conditions

problem reportedly occurred.

Before entering self-diagnostics, perform a careful and

complete visual inspection. Most engine control problems result from

mechanical breakdowns, poor electrical connections or

damaged/misrouted vacuum hoses. Before condemning computerized system,

perform each test listed in article.

NOTE: Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM)

with a minimum 10-megohm input impedance, unless stated

otherwise in test procedure.

PRELIMINARY INSPECTION & ADJUSTMENTS

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed,

stretched, cut or pinched wiring. Ensure electrical connectors fit

tightly and are not corroded. Ensure distributor cap and rotor are

free of cracks, carbon trails or contamination. Ensure vacuum hoses

are properly routed and not pinched or cut. See M - VACUUM DIAGRAMS

article in the ENGINE PERFORMANCE Section to verify routing and

connections (if necessary). Inspect air induction system for possible

vacuum leaks.

MECHANICAL INSPECTION

Compression

Check engine mechanical condition with a compression gauge,

vacuum gauge, or an engine analyzer. See engine analyzer manual for

specific instructions.

WARNING: DO NOT use ignition switch during compression tests. Use a

remote starter to crank engine. Fuel injectors on many models

are triggered by ignition switch during cranking mode, which

can create a fire hazard or contaminate engine’s oiling

system.

COMPRESSION SPECIFICATIONS TABLE (1)

Application Specification

psi (kg/cm

)

1.5L (VIN X) . . . . . . . .. 137 (9.6)

1.6L (VIN Y) . . . . . . . . 171 (12.0)

1.8L (VIN T) . . . . . . . .. 131 (9.2)

2.0L (VIN R) DOHC . . . . . . . 137 (9.6)

2.0L (VIN U) DOHC Turbo . . . . ... 114 (8.0)

2.0L (VIN V) SOHC . . . . . . . 119 (8.4)

2.4L (VIN W) SOHC . . . . . . . 119 (8.4)

3.0L (VIN S) SOHC . . . . . . . 119 (8.4)

3.0L (VIN B) DOHC . . . . . . . 139 (9.8)

3.0L (VIN C) DOHC Turbo . . . . ... 115 (8.1)

(1) - Maximum variation between cylinders 14 psi

(1.0 kg/cm

)

Exhaust System Backpressure

Exhaust system can be checked with a vacuum or pressure

gauge. Remove O2 sensor or air injection check valve (if equipped).

Connect a 1-10 psi pressure gauge and run engine at 2500 RPM. If

exhaust system backpressure is greater than 1 3/4-2 psi, exhaust

system or catalytic converter is plugged. If a vacuum gauge is used,

connect vacuum gauge hose to intake manifold vacuum port and start

engine. Observe vacuum gauge. Open throttle part way and hold steady.

If vacuum gauge reading slowly drops after stabilizing, exhaust system

should be checked for a restriction.

FUEL PRESSURE

Basic diagnosis of fuel system should begin with determining

fuel system pressure.

FUEL INJECTED ENGINES

WARNING: ALWAYS relieve fuel pressure before disconnecting any fuel

injection-related component. DO NOT allow fuel to contact

engine or electrical components.

Fuel Pressure

1) On all models except Colt and Mirage, disconnect fuel pump

harness connector at fuel tank. On Colt and Mirage, remove rear seat

cushion to disconnect fuel pump harness connector.

2) On all models, start engine. Let engine run until it

stops. Turn ignition off. Disconnect negative battery terminal.

Connect fuel pump harness connector.

WARNING: Before disconnecting high pressure fuel hose at fuel delivery

pipe, cover fuel hose connection with a rag. Some residual

fuel pressure may still be in system.

3) On Galant 2.0L (DOHC), remove brace for access to high

pressure fuel delivery pipe. On all engines, disconnect high pressure

fuel hose at fuel delivery pipe.

4) Connect fuel pressure gauge with adapter between fuel

delivery pipe and high pressure hose. See Fig. 1. Connect negative

battery terminal. Connect battery voltage to fuel pump test terminal.

See FUEL PUMP TEST TERMINAL LOCATION table. Ensure no fuel leaks are

present. Disconnect battery voltage to fuel pump test terminal.

Fig. 1: Fuel Pressure Testing Connection ID (Typical Fuel Inj. Eng.)

Courtesy of Mitsubishi Motor Sales of America.

5) Start engine and let idle. Measure fuel pressure with

vacuum hose connected to fuel pressure regulator. Record fuel pressure

reading. Disconnect and plug vacuum hose from fuel pressure regulator.

Record fuel pressure reading. See REGULATED FUEL PRESSURE table.

6) Check for fuel pressure in fuel return hose by gently

pinching hose while increasing engine speed. If fuel volume is low,

fuel pressure in return hose will not be felt. Increase engine speed

to 2500-3000 RPM, 2-3 times. Return engine to idle. Fuel pressure

should not drop when engine is returned to idle.

7) Turn engine off. Ensure fuel pressure reading does not

decrease within 2 minutes. If a decrease is noted, monitor speed of

decrease.

8) If fuel pressure is lower than specification, fuel

pressure drops at idle after increasing engine speed to 2500-3000 RPM,

or no fuel pressure in fuel return hose can be felt, check for clogged

fuel filter, faulty fuel pressure regulator, or fuel pump.

9) If fuel pressure is higher than specification, check for a

faulty fuel pressure regulator or plugged fuel return line. If fuel

pressure does not change when vacuum hose to regulator is connected or

disconnected, check for a leaking or clogged vacuum hose to fuel

pressure regulator or faulty fuel pressure regulator.

10) If fuel pressure decreases suddenly after engine is

stopped, check valve within fuel pump is not seated. Replace fuel