Engine fault diagnostics (Renault Clio 1)

The engine does not turn over when I try to start it

• The battery terminal connections are loose or corroded ("Weekly checks").
• The battery is discharged or faulty (Section 5A).
• The wiring in the starter circuit is broken, loose or disconnected (Section 5A).
• The starter solenoid or switch is faulty (Section 5A).
• Starter faulty (Section 5A).
• The teeth of the starter pinion or flywheel ring gear are broken (Sections 2 and 5A).
• The engine grounding belt is broken or disconnected (Section 5A).

The engine turns over but does not start

• Empty fuel tank.
• The battery is discharged (the engine rotates slowly) (Section 5A).
• The battery terminal connections are loose or corroded (Section 1).
• Ignition components are bypassed or damaged - gasoline models (Sections 1 and 5).
• Broken, loose, or disconnected wiring in the ignition circuit - gasoline models (Sections 1 and 5).
• Spark plugs are worn, defective or the gap is incorrectly adjusted - models with a gasoline engine (Section 1).
• Pre-heating system is faulty - diesel models (Section 5).
• Fuel injection system is faulty - models with petrol engine (Section 4).
• Fuel shut-off valve faulty - diesel models (Section 4).
• Air in the fuel system - diesel models (Section 4).
• Serious mechanical failure (for example, the camshaft drive) (Section 2).

View the original source on this resource: www.RenaultBook.ru

A cold engine is difficult to start

• The battery is low (Section 5A).
• The battery terminal connections are loose or corroded (Section 1).
• Spark plugs are worn, defective or the gap is incorrectly adjusted - models with a gasoline engine (Section 1).
• Pre-heating system is faulty - diesel models (Section 5).
• Fuel injection system is faulty - models with petrol engine (Section 4).
• Other ignition system fault - petrol engine models (Sections 1 and 5).
• The fast idle valve is not adjusted correctly - diesel models (Section 4).
• Low compression in engine cylinders (Section 2).

A warm engine is difficult to start

• The air filter element is dirty or blocked (Section 1).
• Fuel injection system malfunction - petrol models (Section 4).
• Low compression in engine cylinders (Section 2).

The starter is noisy or engages roughly with the flywheel ring gear

• The teeth of the starter pinion or flywheel ring gear are broken (Sections 2 and 5A).
• Starter mounting bolts are loose or missing (Section 5A).
• The internal components of the starter are worn or damaged (Section 5A).

The engine starts but immediately stalls

• Weak or defective ignition system electrical circuits - gasoline engine models (Sections 1 and 5).
• Vacuum leak in the throttle body or intake manifold - gasoline models (Section 4).
• Clogged injector/malfunction in the fuel injection system - models with a petrol engine (Section 4).

Unstable operation in idle mode

• The air filter element is blocked (Section 1).
• Vacuum leak in the throttle body, intake manifold, or associated hoses - gasoline models (Section 4).
• Spark plugs are worn, defective or the gap is incorrectly adjusted - models with a gasoline engine (Section 1).
• Uneven or low compression in engine cylinders (Section 2).
• The camshaft cams are worn out (Section 2).
• The timing belt is not tensioned correctly (Section 2).
• Clogged injector/malfunction in the fuel injection system - models with a petrol engine (Section 4).
• Faulty injector - diesel models (Section 4).

Misfires at idle

• Spark plugs are worn, defective or the gap is incorrectly adjusted - models with a gasoline engine (Section 1).
• Faulty spark plug high voltage wiring - petrol engine models (Section 1).
• Vacuum leak in the throttle body, intake manifold, or associated hoses - gasoline models (Section 4).
• Clogged injector/malfunction in the fuel injection system - models with a petrol engine (Section 4).
• Faulty injector - diesel models (Section 4).
• Distributor cap cracked or burned inside - petrol models (where it is applied) (Section 5).
• Uneven or low compression in engine cylinders (Section 2).
• The crankcase ventilation hoses are disconnected or damaged (Section 4).

Misfires in all operating modes

• The fuel filter element is clogged with dirt (Section 1).
• The fuel pump is faulty or the supply pressure is low - models with a gasoline engine (Section 4).
• The drain hole in the fuel tank is blocked, or the cross-section of the fuel lines has decreased (Section 4).
• Vacuum leak in the throttle body, intake manifold, or associated hoses - gasoline models (Section 4).
• Spark plugs are worn, defective or the gap is incorrectly adjusted - models with a gasoline engine (Section 1).
• Faulty spark plug high voltage wiring - petrol engine models (Section 1).
• Faulty injector - diesel models (Section 4).
• Distributor cap cracked or burned inside - petrol models (where it is applied) (Section 5).
• Defective ignition coil - models with petrol engine (Section 5).
• Uneven or low compression in engine cylinders (Section 2).
• Clogged injector/malfunction in the fuel injection system - models with a petrol engine (Section 4).

The engine misfires when the gas pedal is pressed

• Spark plugs are worn, defective or the gap is incorrectly adjusted - models with a gasoline engine (Section 1).
• Vacuum leak in the throttle body, intake manifold, or associated hoses - gasoline models (Section 4).
• Clogged injector/malfunction in the fuel injection system - models with a petrol engine (Section 4).
• Faulty injector - diesel models (Section 4).

The engine stalls

• Vacuum leak in the throttle body, intake manifold, or associated hoses - gasoline models (Section 4).
• The fuel filter is clogged with dirt (Section 1).
• The fuel pump is faulty or the supply pressure is low - models with a gasoline engine (Section 4).
• The drain hole in the fuel tank is blocked, or the cross-section of the fuel lines has decreased (Section 4).
• Clogged injector/malfunction in the fuel injection system - models with a petrol engine (Section 4).
• Faulty injector - diesel models (Section 4).

The engine does not develop full power

• The timing belt is incorrectly installed or tensioned (Section 2).
• The fuel filter is clogged with dirt (Section 1).
• The fuel pump is faulty or the supply pressure is low - models with a gasoline engine (Section 4).
• Uneven or low compression in engine cylinders (Section 2).
• Spark plugs are worn, defective or the gap is incorrectly adjusted - models with a gasoline engine (Section 1).
• Vacuum leak in the throttle body, intake manifold, or associated hoses - gasoline models (Section 4.)
• Clogged injector/malfunction in the fuel injection system - models with a petrol engine (Section 4).
• Faulty injector - diesel models (Section 4).
• Incorrect injection timing - diesel models (Section 4).
• Wheel braking (Sections 1 and 9).
• Clutch slippage (Section 6).

The engine backfires

• The timing belt is incorrectly installed or tensioned (Section 2).
• Vacuum leak in the throttle body, intake manifold, or associated hoses - gasoline models (Section 4).
• Clogged injector/malfunction in the fuel injection system - models with a petrol engine (Section 4).

The oil pressure warning light comes on when the engine is running

• Low oil level, or wrong grade of oil has been added ("Weekly checks").
• The oil pressure sensor is faulty.
• The crankshaft bearing shells and/or oil pump are worn out (Section 2).
• High engine operating temperature (Section 3).
• The oil pressure reducing valve is faulty (Section 2).
• Clogged oil pump inlet pipe mesh filter (Section 2).

The engine runs after being turned off

• Excessive carbon deposits in the engine (Section 2).
• High engine operating temperature (Section 3).
• Fuel injection system malfunction - petrol models (Section 4).
• Defective fuel shut-off valve - diesel models (Section 4).

Engine noise

• Pre-ignition (detonation) or detonation under acceleration or load.
• Incorrect ignition timing/ignition system fault - petrol models (Sections 1 and 5).
• Spark plugs are not suitable for the engine type - petrol models (Section 1).
• Wrong type of fuel.
• Vacuum leak in the throttle body, intake manifold, or associated hoses - gasoline models (Section 4).
• Excessive carbon deposits in the engine (Section 2).
• Clogged injector/malfunction in the fuel injection system - models with a petrol engine (Section 4).

Whistling and hissing noise when the engine is running

• Leaking intake manifold gasket or throttle body gasket - gasoline models (Section 4).
• Leaking exhaust manifold gasket or exhaust pipe to manifold connection (Section 4).
• Vacuum hose leak (Sections 4 and 9).
• Damage to the cylinder head gasket (Section 2).

Tapping or rattling

• The valve mechanism or camshaft is worn out (Section 2).
• Auxiliary components are damaged (water pump, generator, etc.) (Sections 3, 5 etc.).

Low frequency knocking

• The connecting rod bearings are worn out (regular, intense tapping, possibly weakening under load) (Section 2).
• The main bearings are worn out (a rumbling or knocking noise, possibly increasing under load) (Section 2).
• Piston knock (most noticeable when the engine is cold) (Section 2).
• Auxiliary components are damaged (water pump, generator, etc.) (Sections 3, 5 etc.).