An old car drives off jerkily from a stop sign, tires screeching as it lurches and bucks, with shotgun bangs coming from the tailpipe. The exhaust is puffing blue-black from the tailpipe and the ancient sedan shudders to a stop. A final pop from the exhaust closes this familiar scene.
For driving enthusiasts, backfiring is cool. We hear the pops and see the flames spit from race car exhausts, and we love the aggressive sound when our own cars do it. But like so much that looks and sounds cool, it’s not healthy in copious amounts.
Engine backfire is caused by combustion or an explosion produced by a running internal combustion engine that occurs in the exhaust system rather than inside the combustion chamber.This can cause damage to your car’s exhaust or intake if left unchecked and it also means that your car’s engine isn’t making as much power as it should and also wasting lots of fuel.
Sometimes a flame can be seen when a car backfires, but mostly you will only hear a loud popping noise, followed by loss of power and forward motion.
Some of the most common reasons for a backfire are listed below:
5 Reasons Your Car’s Engine Backfire
1)Engine timing is incorrect
If the timing of the spark is a bit too late in the engine cycle, unburnt fuel and air may be allowed to flow through the exhaust.Delayed timing means that the ignition cycle of your engine starts late in the combustion chamber, and ignites the fuel as soon as the exhaust valve is opening instead of waiting for it to be fully open.
2)High Fuel-to-Air Ratio
If your engine is being supplied more fuel than it needs to burn efficiently, it’s called a rich fuel to air mixture. It can be caused by a multitude of issues including some as straightforward as a dirty air filter. When an engine runs too rich, there is too much fuel to create an explosive, fast-burning flame.
If your engine is getting more fuel than it needs, a rich fuel to air ratio is the result. When your car has leftover fuel in the exhaust and the cylinders, that fuel explosively burns and creates a loud popping sound.
3)Broken Distributor Cap
In vehicles that don’t have ignition coils on the spark plugs, a distributor cap and wire set are used to disperse the electrical pulse to the spark plugs. This electrical pulse is what causes the spark plug to spark and ignite the fuel in its cylinder.
If a distributor cap is cracked, moisture can get in and cause the spark from one cylinder to track to another, incorrect cylinder. When the incorrect cylinder fires out of time when the exhaust valve is open, you will experience a backfire.
4)Carbon tracking on spark plug wires
When talking about what makes a car backfire, we have to think about carbon tracking. Carbon tracking can happen to all types of vehicles – the models that use distributor cap and the ones that have ignition coils.
In an old vehicle with a distributor cap, the sparks can go crossways from one wire to another due to environmental factors. In case if it becomes a regular phenomenon, a carbon that functions as a shortcut to the spark will make the car to backfire.
The second most common scenario is when spark plug wires or ignition coils are mounted directly onto the spark plug, causing the electrical spark to split paths and leaving fuel behind in the cylinder. When the next spark is generated, it strikes at the fuel left behind and rapid burn occurs, while the exhaust valve is open and you have another backfire.
How To Stop Backfire
There are lots and lots of reasons why your car is backfiring. Rather than embark upon an expensive fact-finding mission with your technician, we recommend taking care of some basic maintenance that, a) you already need, and b) could very well be the source of your backfiring.
Old spark plugs and wires, clogged fuel filters, worn fuel pumps, erratic engine timing, and air flow issues are related to that delicate balance of fuel and air that is the key to healthy combustion.
An imbalance in one area can cause the other areas to work harder to compensate.
That creates the potential for faster wear of the system as a whole, and for anomalies that shouldn’t cause backfiring, but do. Therefore, your best bet for keeping combustion where it belongs is to ensure the health of your combustion process. It’s better to fix the 98% that’s easy first rather than going after the rogue 2%.
Steps you can follow to stop your car backfire:
- Change oxygen sensors
- Stop air leaks
- Renew that spark
- Check engine belts
- Keep a healthy exhaust
- Check the distributor cap