Why is my car backfiring suddenly?
We often think of old, rusty trucks when we hear the pops
and bangs of a backfiring engine, but any engine can backfire. Even the one
under your car's hood!
Modern engineering, on the other hand, has made it possible
for cars to have sophisticated engines with variable valve timings and
computer-controlled spark timings that make backfiring almost impossible. If
your engine has been making loud noises that make you think it might have
backfired, read on. We'll tell you the five things that most often cause things
to go wrong.
The first reason could be caused by a Lean Air fuel mixture.
This can happen if you don't put enough gas in the engine.
See, if there isn't enough fuel mixed with the air in the engine, the mixture
will burn more slowly. This means that when the exhaust valves open, there will
still be unburned gasoline ready to be dumped into the exhaust. This problem
could be caused by clogged fuel injectors, a broken fuel pump, or even a
pressure leak in the fuel system.
The second reason could be a Rich Air fuel mixture.
Not only does your engine's spark have to go off and its
valves must close at the right time, but it also has to burn the right amount
of air and fuel. If too much fuel is put into the engine, it might not all burn
up before the exhaust valves open. This could let unburned gasoline into the
red-hot exhaust headers, where it could catch fire and cause a backfire.
Your engine could be getting too much fuel because the fuel
injectors are broken and leaking or because the engine sensors are broken. If
the sensors on the engine send the computer wrong information, the computer may
try to make up for it by adding more fuel than it needs to. To fix this, you
may need to have your car's fuel system cleaned, replace some O2 sensors, or
replace the mass airflow sensor.
Another culprit could be a bent or damaged valve.
As you can see, timing is an important part of making sure
your engine runs smoothly and safely. In interference engines, the valves open
into the space where the rising piston will soon be, so the valves must close
before the piston gets there. If the engine timing system breaks, the pistons
could hit the open valves, which could bend or break them. This will make it
hard for them to make a good seal when they are shut, which could let the
engine backfire. Even though this kind of damage is rare, it is very bad, and
your engine will need a lot of work to get it back in shape.
An incorrect spark firing order could also contribute to an
engine backfire or misfire.
Today's electronically controlled engines with coil-on-plug
ignition systems pretty much eliminate this problem, but on older models with
spark distributors and spark plug wires, the spark plugs could be connected to
the distributor in the wrong order. If the spark goes off in the wrong cylinder
at the wrong time, among other things, the engine will backfire. This problem
can also happen if the spark plug wires are crossed, like after you get new
spark plugs, but again, most modern cars are built to avoid this problem. Yay
for making progress!
Finally, Bad Ignition Timing could be the root problem.
In a modern combustion engine, at least one intake valve and one exhaust valve are in each cylinder. The intake valve opens to let air and/or fuel into the combustion cylinder, where it can be ignited to make power. The exhaust valve then opens to let the byproducts of combustion leave the car through the exhaust.
Hundreds or even thousands of times per minute, these valves
must open and close at the exact right time. This could go wrong if the timing
is even just a little bit off. If the intake valve doesn't close all the way
before the spark, fuel can burn in the intake manifold, making a loud bang and
making your engine run less smoothly and with less power. Or, if the exhaust
valve opens too soon, it can let unburned fuel into the exhaust before it's all
burned up. Instead, it will burn in the exhaust, which will make a loud noise,
do nothing for your engine, and could even send flames out of the tailpipe.
If you are having any sort of engine backfire it is vitally
important that you bring your car or truck into Central Florida Transmission
Repair and let our expert technicians and mechanics help you diagnose what is going
on under the hood. Call us today!
