Skip the auto shop - Our mechanics make house calls

What Does Ignition Timing Mean?

Spark Plug Arc

Timing – it has a couple of different meanings when applied to your car’s engine. One of the most critical is ignition timing (not to be confused with engine timing). Ignition timing refers to when spark is created during the engine’s cycle. It needs to be just right or you end up losing power, increasing fuel consumption and producing more emissions in your exhaust.

What’s timing all about?

Your engine runs on a controlled series of explosions. Spark plugs create their spark to ignite fuel vapors. This creates combustion. The explosion then pushes down the piston, which turns the camshaft. However, the plug can’t fire at just any time. It needs to be timed correctly with the engine’s motion.

There are four cycles in an automotive engine (thus the name four stroke). These are:

  • Intake
  • Compression
  • Combustion
  • Exhaust

The spark plug must fire at the right point in these cycles to maximize the power created by combustion. The system should fire before the piston hits top dead center (TDC). The increase in pressure from combustion pushes the piston back down (after reaching TDC), and turns the camshaft. The reason that the plugs need to fire before the piston hits TDC is that if it didn’t happen then, by the time combustion actually occurred, the piston would be so far into its downward motion that the force of the combustion would be largely wasted.

Remember: while gas is highly combustible, it doesn’t burn instantaneously. There is always a delay. By firing before the piston hits TDC, your engine is able to account for this delay and maximize the amount of power each time.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
P0477 OBD-II Trouble Code: Exhaust Pressure Control Valve Low
P0477 code means that the PCM has detected an abnormally low voltage reading often due to the exhaust back pressure control valve circuit.


Related questions

Q: Randomly doesn't start

Hi There, What you are describing sounds like an ignition coil pack that may be failing. Ignition coils are prone to this type of erratic functioning when they are beginning to fail due to the temperature fluctuations under the hood...

Q: Car not starting

This is a common problem. Although no start conditions can be caused by many things, there are two common issues that come to mind, starter failure and a parasitic drain. Often times when a starter fails it simply does nothing...

Q: Car misses and has a rough idle - 2001 Saturn L100

Hello. There are several things that could be causing your rough idle condition and therefore there are multiple possible solutions. Carbon buildup inside the intake manifold and valve train is a big cause of rough idle. This can usually be...