by J.L. Eck

Created on: April 17, 2009   Last Updated: March 01, 2010

When a car or truck backfires, people duck and cover. The noise coming from the vehicle can cause fellow motorists to wonder if they have been shot at causing them to swerve as the nearby animals flee. Elderly people clutch their chests as their heart races due to the terrible trauma imposed upon them. If it is a really prominent backfire, the cops may even end up at the scene to investigate the noise or death of the elderly pedestrian that keeled over from the surprise!

Essentially, a backfire is a simple chemical reaction. Superheated unburnt fuel escapes the engine via the exhaust valves and travels through the exhaust system. When it reaches oxygen while still above flash-point, it ignites, causing an explosion. This reaction is usually harmless to anything excepting the vehicles fuel mileage, or maybe the muffler. Sometimes, however, it can be a sign of the imminent failure of vital components under the vehicle's hood.

To determine what is happening to the cackling car, one will first need to check if the vehicle has any sensors failing.  It's usually free to go to the local auto-parts store and have the vehicle's engine trouble codes checked. If anything shows up, you are already at the place you will need to be to buy the problem part(s)! Sometimes, many trouble codes will show up on the scan. If this happens, do not buy parts unless you trust the salesman on a personal level, after all, it is their job to sell parts.

When many codes appear, it may be time to move on to checking the vehicles ignition timing components individually.  Parts such as spark plugs, plug wires, oxygen sensors, etc. can be easily replaced, narrowing the search for the problem.   If this seems a daunting task, one should take the vehicle to a mechanic for an in-depth diagnostic scan. There are many reasons a newer vehicle will backfire that hide from even the trained professional.

Amongst the many culprits of a backfire are spark plugs, plug wires, coil or coil packs, and spark distribution module or distributor. It is also a possibility that the timing has "slipped". For this, one would use a timing light to check if the spark is being delivered at the right time to the number one cylinder. Many sensors could be the problem as well. These include the oxygen sensors, map sensor, or any other sensors having to do with air fuel mixtures.  Fuel contamination can lead to these components failing as well.  Replacing them in this circumstance can lead to new sensors failing as well. 

Having exhausted all possibilities in the engine compartment, one may want to check for gremlins in the muffler bearing. If that doesn't work seek professional help!

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