The why and where on how to find your engine's firing order is important if you plan to do maintenance or repair work on your new or used vehicle. New vehicles come with different warranty lengths of time and mileage, as well as what components are covered under those warranties, but most don't cover routine maintenance. You should check the owner's manual to find out what items are under warranty and which are owner responsibility. Used vehicles normally carry little if any warranty, and maintenance items from the time of purchase are at your expense. If you have the mechanical ability to perform at least some of the maintenance or repair on your new or used vehicle, including changing the oil and oil filter, replacing the air filter and changing the spark plugs, replacing the points in the distributor (if so equipped) or the rotor could save you money.
Firing of Spark Plugs
In older conventional engine vehicles, correct firing of the spark plugs in gasoline engines or of the sequence of fuel injection in diesel engines is necessary, as it affects the performance and wear of the engine system and can affect your driving comfort and enjoyment. In newer models with an engine management system and direct ignition, an electronic control unit (ECU) directs the firing sequence. Normally, if your vehicle is running smoothly, not backfiring and obtaining close to the estimated mpg rating, and you are replacing the spark plugs or spark plug wires for maintenance reasons, your firing order is probably correct. Mark the plug wires and locations as you remove them and you will not need to know the firing order. If there have been any running problems or the wires were not marked when removed, then you will need to know the correct firing order.
Finding the Correct Firing Order
One of the ways to locate the correct firing order for your vehicle can be as simple as locating the information on the engine, usually on the cylinder head. Sometimes it's located on the valve covers, and occasionally on the intake manifold. Some manufacturers put this information in the owner's manual under the specifications information.
Another way to find the firing order for your vehicle is by using a repair manual. Repair manuals are available for purchase at auto parts stores, from some manufacturers or online at some book sites. Some libraries have manuals available for checking out for your use as well.
Many people find and use information available on web sites for how-to-do repairs, including the specific steps needed to complete a repair, the specifications and more.
Now that you know where to locate your engine's firing order and what the order is, you are ready to complete the repairs or maintenance on your vehicle.