What Happens If A Car Has A Bad Cylinder, What Happens If A Car Has A Bad Cylinder?  [8 Common Symptoms], KevweAuto

What Happens If A Car Has A Bad Cylinder? [8 Common Symptoms]

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Inside your engine’s cylinder block are the precisely machined cylinders that house the pistons. Each cylinder must fire properly to generate maximum power and efficiency. When one or more engine cylinders go bad, it creates a cascade of drivability and mechanical issues. Understanding what happens if a car has a bad cylinder will help motivate prompt diagnosis and repair. This guide details the common symptoms and vehicle damage caused by a malfunctioning engine cylinder.

Cylinder Basics – A Closer Look Inside

What Happens If A Car Has A Bad Cylinder, What Happens If A Car Has A Bad Cylinder?  [8 Common Symptoms], KevweAuto

At its most basic level, a cylinder consists of a cylindrical bore that houses a piston connected to a crankshaft. As the piston travels up and down inside the cylinder, this linear motion gets converted into rotational movement through the connecting rod and crankshaft. But several other components play key roles:

Cylinder Head – Seals the top of the cylinder and contains the valves for air intake and exhaust. The head also forms the combustion chamber space.

Cylinder Walls – The inner bore surface where the piston travels up and down. Made of durable iron alloys that withstand heat and friction.

Piston Rings – Steel rings that seal the gap between the piston and cylinder wall. They prevent combustion gas blowby and regulate oil distribution on the cylinder walls.

Spark Plug – Provides the high voltage spark for igniting the compressed air/fuel mixture inside the combustion chamber.

Cooling Jackets – Hollow channels surrounding cylinders where engine coolant flows to dissipate heat and prevent overheating.

These components all work together to enable the careful orchestration of the intake, compression, combustion, and exhaust stages that result in usable engine torque.

Manufacturers combine various cylinder technologies with these configurations to tailor an engine’s power delivery for its vehicle application.

Key Components and Technologies That Optimize Cylinder Function

What Happens If A Car Has A Bad Cylinder, What Happens If A Car Has A Bad Cylinder?  [8 Common Symptoms], KevweAuto

Aside from the cylinder and head themselves, various components and technologies help maximize combustion efficiency:

Variable Valve Timing/Lift – Altering intake and exhaust timing/duration optimizes cylinder filling and emptying across the rev range. This provides a broader powerband.

Direct Fuel Injection – Injecting fuel straight into the cylinder enables finer control over mixtures for increased efficiency and power versus port injection.

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Forced Induction – Turbochargers and superchargers cram more air into cylinders by increasing intake pressure for added performance.

Cylinder Deactivation – Shutting down certain cylinders during light load conditions reduces fuel consumption. GM’s Active Fuel Management is one example.

Cooled Exhaust Gas Recirculation – Recirculating cooled exhaust gas back into the cylinders lowers combustion temperatures and reduces throttling losses.

Thermal Barriers – Ceramic thermal barrier coatings on piston crowns or cylinder head surfaces shield components from excessive heat transfer.

Oil Jet Piston Cooling – Spraying a jet of oil at the bottom of the piston cools piston crowns and reduces the chance of detonation.

Engineering refinements like these ensure maximum efficiency and power is extracted from every drop of fuel.

What Happens If A Car Has A Bad Cylinder?

Here are the highlighted common symptoms caused by a malfunctioning engine cylinder.

1. Loss of Power

One of the first obvious effects is reduced engine power and performance:

  • Misfires – The bad cylinder fails to combust the air/fuel mixture, so it does not add power.
  • Reduced displacement – Total engine displacement in terms of cubic inches or liters drops by the amount the cylinder represents.
  • Lean operation – Operating cylinders run leaner as the computer reduces fuel to balance misfires.
  • Increased load – The remaining functional cylinders work harder to compensate, increasing strain.
  • Acceleration deficits – Less total power output leads to sluggish acceleration and difficulty maintaining speed.
  • Load hauling deficits – Lugging heavy loads taxes the engine further and feels even more strained.

Address bad cylinders promptly to restore full engine power and performance capabilities.

2. Surging and Rough Idling

The intermittent contribution of a bad cylinder creates an imbalanced engine operation:

  • Surging speed – Engine speed surges up and down as the cylinder intermittently fires and misfires.
  • Vibrations – The missing power strokes create a rougher, shakier idle with more vibrations.
  • Stalling – An extreme misfire at idle can kill the engine completely.
  • Hard restarting – The rough running makes the engine harder to restart after stalling.
  • Backfiring – Lean backfires and explosions in the exhaust occur as fuel ignites there.

Isolate bad cylinders by paying attention to where surges and vibrations are strongest.

3. Increased Fuel Consumption

What Happens If A Car Has A Bad Cylinder, What Happens If A Car Has A Bad Cylinder?  [8 Common Symptoms], KevweAuto

Several factors contribute to reduced fuel economy with a bad cylinder:

  • Misfires waste fuel – Fuel injected gets exhausted unburnt during misfires.
  • Excess fuel enrichment – Computers add more fuel to try stabilizing lean cylinders.
  • Higher loads – Operating cylinders run less efficiently under increased loads.
  • Spark timing retard – Retarded ignition timing reduces combustion efficiency.
  • Idling – More time spent idling further lowers miles per gallon.
  • Check engine light – Illuminated engine lights themselves impact fuel economy.
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Expect your gas mileage to drop noticeably with a bad cylinder until it can be fixed.

4. Engine Overheating

Heat generation ramps up in an engine with a bad cylinder:

  • Lean conditions – Cylinders run hotter and at greater risk of preignition when lean.
  • Increased effort – Higher loads generate more heat in the working cylinders.
  • Combustion timing – Premature or late ignition creates extremely high temperatures.
  • Cooling capacity – More heat eventually overwhelms the engine cooling system.
  • Oil breakdown – Higher temperatures also break down lubricating oil into sludge.

Sustained overheating can warp cylinder heads, damage head gaskets, and necessitate major engine work.

5. Catalytic Converter Damage

What Happens If A Car Has A Bad Cylinder, What Happens If A Car Has A Bad Cylinder?  [8 Common Symptoms], KevweAuto

Unburnt fuel and oxygen sent into the exhaust system overheat and damage the catalytic converter:

  • High temperatures – The excess oxygen and fuel create greater exothermic reactions.
  • Melting – The catalyst structure melts from prolonged exposure to very high temperatures.
  • Clogging – Carbon buildup chokes off exhaust flow through the brick.
  • Contaminants – Unburnt fuel, soot and additives coat and foul the catalyst.
  • O2 sensor damage – Excess oxygen also overheats and damages the O2 sensors.

Catalytic converter and sensor failures trigger even more warning lights and reduced performance.

6. Knock and Preignition

As cylinder pressures and temperatures climb, the chances of preignition and engine knock rise:

  • Audible knock – Loud metallic pinging results from premature ignition of the air/fuel mixture.
  • Cylinder pressure spikes – Uncontrolled ignition causes violent pressure spikes that stress components.
  • Piston and head damage – The extreme heat and pressure leads to melted areas, holes or cracks over time.
  • Connecting rod risk – Knock substantially increases the chances of a rod bending or breaking.
  • Engine run-on – Severe preignition causes runaway combustion even with no spark.

Knock and preignition place incredible stress on an engine and can lead to catastrophic failure if left unchecked.

7. Increased Emissions

A bad cylinder allows more harmful emissions to exit the tailpipe:

  • Unburnt hydrocarbons – Fuel not fully combusted gets exhausted as pollution.
  • Excess carbon monoxide – Incomplete combustion also spikes CO levels.
  • Higher NOx – Lean cylinders and high temperatures increase NOx production.
  • Fouled catalytic converter – Damage to the catalyst allows more engine pollution through.
  • Check engine light – Emissions computers turn on the check engine light due to the imbalance.
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Poor emissions make the vehicle run more dirty and risk failing inspection and emissions tests.

8. Accelerated Wear

The extreme conditions inside a misfiring cylinder accelerate wear on components:

  • Piston ring fouling – Carbon deposits keep rings from sealing properly against cylinder walls.
  • Valve recession – Heat causes valves to warp and pull away from seats, reducing compression.
  • Bearing wear – Overloaded bearings lose lubrication film strength resulting in scuffing.
  • Piston scuffing – Lean operation leads to piston skirts overheating and scuffing against cylinder walls.
  • Gasket failure – Blowby gases and distortion compromise head gaskets and cause leaks.

If worn components are not replaced, oil consumption, blowby, and power loss continues to worsen.

When Engine Rebuilds or Replacements Are Necessary

If properly maintained, cylinders may only need occasional replacement of piston rings and valve jobs. But if an engine experiences neglected maintenance, overheating, or excessive load, major repairs or replacements may become necessary:

Cylinder Boring – Badly scored cylinders require boring out and honing to restore proper dimensions for new piston ring sets. This may also necessitate oversized pistons.

Cylinder Head Replacement – Cracks, warpage, or erosion damage may make replacing the entire cylinder head more feasible than attempting to resurface or repair it.

Engine Block Replacement – If cracks or damage in the cylinder bores are beyond machining tolerances, a new engine block may be in order. This also necessitates all new internals.

Complete Engine Replacement – In some situations, it is simpler and more cost-effective to replace the entire engine with a new or low-mileage used unit versus attempting to rebuild the original.

No technician enjoys informing a customer that their cylinder damage warrants major repairs. But engines can deliver many more miles when rebuilt properly or replaced with quality components.

Keep Your Cylinders Running Strong

What Happens If A Car Has A Bad Cylinder, What Happens If A Car Has A Bad Cylinder?  [8 Common Symptoms], KevweAuto

The deceptively simple engine cylinder converts rapid gas expansion into usable power through carefully engineered sequences. With routine care and diligent maintenance, cylinders provide thousands of miles of reliable service. Key points covered include:

  • Cylinder bores house pistons connected to the crankshaft to produce power
  • Displacement, compression ratio, and fuel mixes impact output
  • Various cylinder arrangements and technologies exist
  • Symptoms like knocking require diagnosis to avoid further damage
  • Rebuilding or replacing cylinders is sometimes necessary


Cylinder problems indicate a neglect of proper maintenance or a pending engine failure. Address bad cylinders promptly to avoid destroying your engine completely. With proper care and maintenance, your engine can provide many more miles of trouble-free service.

Oghenerume Ezekiel

Oghenerume Ezekiel is an enthusiastic automobile blogger with a deep passion for all things cars. With over 5 years of experience test driving, reviewing, automobile repair, automobile maintenance, and writing about the latest models, Ezekiel provides readers with detailed yet easy-to-understand evaluations. His specialty is breaking down complex mechanical details into layman terms that both car novices and experts can appreciate.

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