There are typically two kinds of
engine backfires, one is
generated from the intake manifold
of the engine, and the second is
expelled from the exhaust pipe
at the rear of the car. A backfire is an explosion of sorts in the intake manifold
or the exhaust system. A backfire occurs when there is an imbalance in the air to
fuel ratio required for your vehicle to operate properly. If the fuel mixture is
too lean (not enough fuel) you may have a backfire in the intake, or too rich (too
much fuel) you may get a backfire out of the exhaust system. Most backfires are
easily repaired by correcting the imbalance and providing a greater or lesser percentage
of fuel to the mixture.
Common Problems and Solutions
Most causes of backfires in the exhaust system can be addressed by
troubleshooting the reason for the
air to fuel ratio imbalance. The solution usually involves checking for
vacuum leaks, changing the
oxygen sensor, or fuel filter
to ensure the fuel system is functioning properly.
A common backfire situation occurs when there is a small leak in the
air injection system that feeds the
exhaust system. This can cause unburned fuel to explode suddenly. One of the most
common causes is a stuck or faulty air intake or gulp valve near the exhaust manifold.
Backfiring can also occur with a sudden
drop in fuel
pressure. This may be due to a faulty fuel pump or a plugged fuel filter. Correcting
problems in the fuel system usually resolves these issues.
Incorrect ignition timing to the spark plugs is another cause of backfire. Adjusting
the ignition distributor, if the engine is so equipped, may resolve this problem.
Adjusting engine timing is not difficult and can be done with a timing light by
following the timing adjustment procedure for your car. If you do not know your
car's ignition timing procedure please visit our car repair manual page. A vehicle
that is not timed properly will not idle, run or operate correctly and will often
backfire rapidly. On newer cars you will need to scan the pcm to check for CKS (crankshaft
angle sensor) and CMS (camshaft position sensor) related trouble codes.
To prevent backfires there are a few things you can do:
Change the fuel filter as
needed, the fuel filter is a vital part of your fuel system and can cause a backfire(s)
if the filter is clogged and not changed regularly. A bad fuel filter can
cause low fuel pressure creating a perfect situation for a backfire to occur. Changing
the filter is simple and can save gas with improved performance of your vehicle's
engine reducing the occurrence of backfires.
Tune up and service your fuel
injection system in accordance with the maintenance schedule for your particular
car. This ensures correct fuel consumption with the correct amount of emissions.
Fuel that is not burned completely will leave ample opportunity for a backfire to
occur. These maintenance requirements are associated with other systems on your
vehicle. Avoiding maintenance of your car can increase the risk of backfiring and
other system malfunctions.
If further assistance is needed, our certified car repair technicians are ready
to answer your car questions.
Related Car Repair Information