If the cap is cracked, it allows moisture to creep in, which causes the electrical spark to jump to the wrong cylinder, causing a backfire. Carbon tracking can come into play in a variety of situations, the first situation involving sparks that are generated by wires on a distributor cap, can start to hop from one wire to another very quickly and thus a carbon track is formed which is essentially a shortcut for the spark.
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.
If you are struggling with a car that backfires, get in contact with us , and let us help you sort the problem out once and for all. We'll look for the following troublemakers:. In newer vehicles, computerized sensors help ensure the air-fuel ratio is correct. However, if a sensor malfunctions, it can throw off the air-fuel ratio, causing sluggish or delayed combustion. If this is the case, your Check Engine light might be screaming at you.
Leaks in the exhaust system, sometimes called vacuum leaks, can sound more like a screech than a bang as excess air gets sucked in. All this extra air mixes with the fuel, creating an incorrect ratio for proper combustion. Even something as simple as a dirty air filter can potentially trigger a backfire. Since air filters allow clean air to flow into your engine, a dirty filter can inhibit the flow of air into the intake, creating a poor fuel-air ratio.
Injectors that supply too little or too much fuel to the cylinder can also create a poor fuel-air ratio.
Spark plugs that fire out of turn or not at all can also cause backfiring. Shorts in wiring, incorrect wiring, or damaged distributor caps that deliver the charge to the wrong plug at the wrong time are much more common in older vehicles. But even in newer cars and trucks, plugs can malfunction due to carbon buildup or wear out over time. In the four-steps of engine combustion, timing is everything.
If the timing is off, valves might open or close at the wrong time, and the spark might arrive early or late. Any time the fuel-air explosion is not properly compressed, ignited, and contained, a backfire can occur. Newer engines with computer-controlled timing are more reliable, and backfires are less likely.
Not all backfires occur when you start the engine. Sometimes one can happen when you shift gears. However, that loud pop that you hear when shifting is, in fact, an afterfire. Most of these occur on manual vehicles where a clutch is used to shift gears. As you press in your clutch and go from one gear to the next, fuel can continue to enter the cylinders, especially if you switch gears at higher RPMs.
Basically, when that plug sparks out of turn, it lights the fuel in the cylinder - and that pressure has to go somewhere This usually goes away once the engine warms-up. A cold engine needs more fuel to run, and a warmer engine runs more efficiently and needs less fuel, so if you are only spitting when the engine is cold, then most likely it's due to a lean condition. You could also check to make sure your choke is working. If it's stuck open when the engine is cold, then it isn't doing its job by richening-up the mixture and it could definitely cause spitting.
Spitting and coughing can also be commonly caused by the accelerator pump in the carb not squirting enough fuel before the main jets start working. If you spit the instant you blip the throttle, then it's probably the accelerator pump in the carb not working, or not squirting enough fuel, so the engine takes a gulp of air and goes lean, which causes the spit back-up through the carb.
This could mean that it's plugged up with some dirt, or a piece of something that got through your fuel filter, or it could just be out of adjustment or maybe the accelerator pump itself has just gone bad and can't squirt any fuel anymore.
That's not too uncommon if the carb is a bit old. For the best deals on your performance parts and accessories with the best service, choose where I order all of my components from
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