A car backfires when the air/fuel mixture in one or more cylinders burns inefficiently. This typically happens on acceleration because that is when there is a large demand for power, which can overwhelm the available oxygen in the exhaust manifold. On over-boosted engines, this problem is exacerbated by additional oxygen not being pulled through the exhaust system, furthering the likelihood of backfires.
A backfire has the potential to damage the catalytic converter and/or burn a hole in a pipe, so it is wise not to ignore them. A misfiring car can be difficult to drive smoothly, but most cars have a "limp mode" that restricts power so you can safely get off the road.
A backfiring car looks cool, but it says about some malfunctions in the process of burning the fuel. So you better have the car checked.
Possible causes of backfire on acceleration are:
- too much fuel in the engine, caused by broken injectors or defective pressure regulators.
- wrong ignition timing. If the camshaft sprocket is out of position with respect to the crankshaft so spark plug fires before the piston reaches the top dead center, the exhaust valve will stay open and allow all the compressed air/fuel mixture to escape to the exhaust manifold.
- wrong type of fuel. Gasoline with an octane rating lower than recommended can cause backfires.
- defects in the combustion chambers, e.g. carbon deposits blocking valves. Carbon deposits are sometimes visible on spark plugs after a backfire happens.
- low compression in one or more cylinders due to worn pistons rings, high valve clearance, etc.
About the authors
The CarAraC research team is composed of seasoned auto mechanics and automotive industry professionals, including individuals with advanced degrees and certifications in their field. Our team members boast prestigious credentials, reflecting their extensive knowledge and skills. These qualifications include: IMI: Institute of the Motor Industry, ASE-Certified Master Automobile Technicians; Coventry University, Graduate of MA in Automotive Journalism; Politecnico di Torino, Italy, MS Automotive Engineering; Ss. Cyril and Methodius University in Skopje, Mechanical University in Skopje; TOC Automotive College; DHA Suffa University, Department of Mechanical Engineering
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