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Land Rover Discovery 1995 – 1994 95 ENGINE PERFORMANCE Trouble Shooting No Codes Defender Discovery

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Land Rover Discovery 1995 - 1994-95 ENGINE PERFORMANCE Trouble Shooting - No Codes - Defender & Discovery


Land Rover Discovery 1995 - INTRODUCTION

Before diagnosing symptoms or intermittent faults, follow proper workflow. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. If no Diagnostic Trouble Codes (DTCs) are present and a no start condition exists, proceed to appropriate BASIC DIAGNOSTIC PROCEDURES article. If no DTCs are present and a driveability condition exists, diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

NOTE: Some driveability problems may have been corrected by manufacturer with a revised computer calibration chip or computer control unit. Check with manufacturer for latest chip or computer application.

Use intermittent test procedures to locate driveability problems that do not occur when the vehicle is being tested. These test procedures should also be used if a soft (intermittent) trouble code was present but no problem was found during self-diagnostic testing.

NOTE: For specific testing procedures, see appropriate SYSTEM & COMPONENT TESTING article. For specifications, see ON-VEHICLE ADJUSTMENTS or SERVICE & ADJUSTMENT SPECIFICATIONS article.


Land Rover Discovery 1995 - SYMPTOMS SYMPTOM DIAGNOSIS


CAUTION: When battery is disconnected, vehicle computer 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 the battery.

Symptom checks cannot be used properly unless problem occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC DIAGNOSTIC PROCEDURES article and appropriate SELF-DIAGNOSTICS article were performed before diagnosing a symptom. Following symptoms are available for diagnosis:


Land Rover Discovery 1995 - ENGINE FAILS TO CRANK IN PARK OR NEUTRAL (A/T)


  • Check battery charge.
  • Check for faulty A/T inhibitor switch.
  • Check for incorrectly adjusted gear selection linkage.

Land Rover Discovery 1995 - ENGINE FAILS TO CRANK (M/T)


  • Check battery charge.

Land Rover Discovery 1995 - ENGINE CRANKS BUT FAILS TO START


  • Check for slow cranking speed (less then 120 RPM).
  • Check for faulty ignition system.
  • Check for low fuel level.
  • Check fuel tank.
  • Check for contaminated fuel.
  • Check for plugged fuel filter.
  • Check for faulty fuel pump.
  • Check for faulty ventilation system.
  • Check for faulty emission control system.

Land Rover Discovery 1995 - ENGINE RUNS AT HIGH RPM BUT WILL NOT IDLE


  • Check fuel injection system.
  • Check power brake booster vacuum connections.
  • Check heater/ventilation unit vacuum connections.
  • Check that secondary ignition wires are correctly routed and secure.
  • Check for low fuel level.
  • Check fuel tank.
  • Check for contaminated fuel.
  • Check for plugged fuel filter.
  • Check for faulty fuel pump.
  • Check for faulty ventilation system.
  • Check for faulty emission control system.

Land Rover Discovery 1995 - ENGINE IDLE SPEED ERRATIC, ENGINE STARTS BUT STOPS IMMEDIATELY


  • Check fuel injection system.
  • Check power brake booster vacuum connections.
  • Check heater/ventilation unit vacuum connections.
  • Check that secondary ignition wires are correctly routed and secure.
  • Check for low fuel level.
  • Check fuel tank.
  • Check for contaminated fuel.
  • Check for plugged fuel filter.
  • Check for faulty fuel pump.
  • Check for faulty ventilation system.
  • Check for faulty emission control system.

Land Rover Discovery 1995 - ENGINE STALLS & ENGINE MISFIRES OR HESITATES


  • Check fuel injection system.
  • Check power brake booster vacuum connections.
  • Check heater/ventilation unit vacuum connections.
  • Check that secondary ignition wires are correctly routed and secure.
  • Check for low fuel level.
  • Check fuel tank.
  • Check for contaminated fuel.
  • Check for plugged fuel filter.
  • Check for faulty fuel pump.
  • Check for faulty ventilation system.
  • Check for faulty emission control system.

Land Rover Discovery 1995 - ENGINE LACKS POWER/POOR PERFORMANCE


  • Check for restricted or incorrectly adjusted throttle cable.
  • Check thickness or carpets.
  • Check for faulty ignition system.
  • Check for faulty fuel injection system.
  • Check for low fuel level.
  • Check fuel tank.
  • Check for contaminated fuel.
  • Check for plugged fuel filter.
  • Check for faulty fuel pump.
  • Check for faulty ventilation system.
  • Check for faulty emission control system.
  • Check for valve held open by hydraulic tappets.
  • Check for high oil pressure.
  • Check oil pressure relief valve strainer gauze for blockage.
  • Check for stuck closed oil pressure relief valve.
  • Check cylinder compression.
  • Check for faulty head gaskets.
  • Check for faulty valves.
  • Check power brake booster vacuum connections.
  • Check heater/ventilation unit vacuum connections.
  • Check for binding brakes.
  • Check for faulty torque converter (A/T).
  • Check for faulty automatic transmission.

Land Rover Discovery 1995 - ENGINE BACKFIRES INTO EXHAUST SYSTEM


  • Check for leaking joints/connection in exhaust system.
  • Check for holes in exhaust system.
  • Check for incorrectly fitted distributor.
  • Check for correct firing order of secondary ignition wires.
  • Check for correct routing or secondary ignition wires.
  • Check for faulty fuel injection system.
  • Check power brake booster vacuum connections.
  • Check heater/ventilation unit vacuum connections.
  • Check crank case and fuel tank ventilation system.
  • Check cylinder compression.
  • Check for leaking gaskets.
  • Check for faulty valves.

Land Rover Discovery 1995 - ENGINE BACKFIRES INTO INLET SYSTEM


  • Check for correct distributor.
  • Check for correct routing of secondary ignition wires.
  • Check for faulty fuel injection system.
  • Check power brake booster vacuum connections.
  • Check heater/ventilation unit vacuum connections.
  • Check crank case and fuel tank ventilation system.
  • Check cylinder compression.
  • Check for leaking gaskets.
  • Check for faulty valves.

Land Rover Discovery 1995 - ENGINE INTERNAL MECHANICAL NOISES (SINGLE OR MULTIPLE, LIGHT TAPPING NOISE, PARTICULARLY WHEN COLD)


  • Check for low oil level.
  • Check oil pressure.
  • Check hydraulic valve lifters.

Land Rover Discovery 1995 - ENGINE INTERNAL MECHANICAL NOISES (HEAVY KNOCKING NOISE, PARTICULARLY ON LOAD AND WHEN ENGINE IS HOT)


  • Check for low oil level.
  • Check oil pressure.
  • Check for oil contamination with metal particles.
  • Check for faulty crankshaft bearing.
  • Check flywheel security.
  • Check crankshaft front pulley security.

Land Rover Discovery 1995 - HEAVY RUMBLING NOISE (PARTICULARLY DURING HARD ACCELERATION)


  • Check for low oil level.
  • Check oil pressure.
  • Check for oil contamination with metal particles.
  • Check for faulty main bearings.
  • Check flywheel security.
  • Check crankshaft front pulley security.

Land Rover Discovery 1995 - INTERMITTENTS PROBLEM DIAGNOSIS


Intermittent fault testing requires duplicating circuit or component failure to identify problem. These procedures may lead to computer setting a fault code (on some systems) which may help in diagnosis.

If problem vehicle does not produce fault codes, monitor voltage or resistance values using a DVOM while attempting to reproduce conditions causing intermittent fault. A status change on DVOM indicates a fault has been located.

Use a DVOM to pinpoint faults. When monitoring voltage, ensure ignition switch is in ON position or engine is running. Ensure ignition switch is in OFF position or negative battery cable is disconnected when monitoring circuit resistance. Status changes on DVOM during test procedures indicate area of fault.


Land Rover Discovery 1995 - TEST PROCEDURES Intermittent Simulation


To reproduce conditions creating an intermittent fault, use the following methods:

  • Lightly vibrate component.
  • Heat component.
  • Wiggle or bend wiring harness.
  • Spray component with water.
  • Remove/apply vacuum source.
Monitor circuit/component voltage or resistance while simulating intermittent. If engine is running, monitor for self-diagnostic codes. Use test results to identify a faulty component or circuit.