Ignition Timing – The Spark Plug, Has To Fire At The Proper Time

Ignition Timing - The Spark Plug, Has To Fire At The Proper Time
Ignition Timing - The Spark Plug, Has To Fire At The Proper Time

Your engine needs proper ignition timing, to ignite the fuel, at exactly the right time.

But, what happens if, the ignition system fires, at the wrong time.

Consequently, the fuel-and-air mixture, will not be burned properly. As a result, power will fall, while fuel consumption and emissions will increase.

Subsequently, this is where, proper ignition timing comes into play. So, you start off with fuel, air, compression and spark. But, for all that to work properly, the spark plug has to fire, at the proper time. Only then, will the air-fuel mixture, burn completely.

Ignition Timing
Top Dead Center – (TDC) When The Piston Is At The Top Of Its Stroke

The way we measure this, is in degrees. This is always before or after, the piston reaches the top dead center (TDC).

Consequently, this measurement is better known as, advanced or retarded timing.

  • So, if the spark ignites the fuel, before the piston reaches (TDC). Then, the ignition timing is said to be, advanced.
  • However, if the spark ignites the fuel, after the piston reaches (TDC). Then, the ignition timing is said to be, retarded.

Manual, Ignition Timing

So, back in the day, most older engines had, manual ignition timing. Consequently, they used either, vacuum advances or centrifugal advances, to set the right advance timing.

Ignition Timing
Vacuum Advance

Whereas, modern engines, have the Engine Control Unit (ECU), to dictate the advance needed, at a given engine speed.

Using A Vacuum Gauge, To Test For Wrong Timing

Wrong ignition timing, also affects manifold vacuum readings.

Ignition Timing
Vacuum Gauge

So, by connecting a vacuum gauge, to a strong vacuum source, lower than normal readings, could indicate wrong timing.

Computerized, Ignition Timing

Newer engines usually use, computerized ignition systems. The computer has, a timing map with spark advance values. And, is used for all combinations, of engine speed and load. Then, the computer will send a signal to the ignition coil, at the indicated time in the timing map.

Electronic Spark Control Module

Also, known as, the (ESC) module or the ignition module. So, the ignition control module, works together with the computer. And, is used to set the engine’s ignition system, for the best performance and efficiency. In other words, one of the specific functions of the (ESC) module. Consequently, is to advance or retard the timing of the ignition system.

Electronic Spark Control (ESC) Module
Electronic Spark Control (ESC) Module

So, under heavy load, the module will advance the timing. And, to increase power and will retard it, at low throttle. Meanwhile, the (ESC) module, makes these changes automatically and smoothly. Almost, to the point where they are, virtually unnoticeable. So, the (ESC) module plays an important role, in the operation of the engine. As a result, any problems with it, can cause issues with the drivability and performance in your engine.

What Can Happen With, Wrong Ignition Timing

Wrong ignition timing, can cause several engine problems, such as:

  • Knocking or Pinging
  • Difficult Starting
  • Excessive Engine Heat
  • Increased Fuel Consumption
  • Reduced Power Output

Knocking or Pinging

Above all, this is one of the most common symptoms, of wrong ignition timing. In these cases, the spark fires when the engine, is still in its compression phase. So, to prevent engine knocking, modern engines use knock sensors.

Difficult Starting

This can be either, due to an advanced or delayed ignition. But, in both cases, the engine will not produce the optimal power. And, cause the vehicle to experience difficulty, while starting.

Excessive Engine Heat

Igniting the air-fuel mixture too early, in the power stroke can cause this.

Excessive Engine Heat
Excessive Engine Heat

This causes the engine, to make more heat than usual.

Increased Fuel Consumption

Consequently, if the spark fires at the wrong time, it will result in improper combustion. In addition, this will also cause the fuel economy to suffer.

Reduced Power Output

If the spark fires late, the piston is already on the way down, generating less power and wasting fuel.

There Are Basically, Three Distinct Types, Of Ignition Systems:

As you can see, there have been great advances over the years.


Consequently, newer engines adjust the ignition timing themselves. So, as long as your sensors are all working properly, you won’t have to do any tinkering with timing. In fact, you usually can’t, unless you remap your ignition computer’s chip. However, you can buy an aftermarket performance chip, that has a different timing map flashed into it.

Be careful because, the wrong chip can not only make your car run badly. But, it can also throw error codes and bring on the dreaded, check engine light.

Thank You !