Why is my truck backfiring
HOW TO FIX AN ENGINE BACKFIRE IN 15 MINUTES!
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hello and welcome to two car pros say
we're going to show you how to fix an
engine that is backfiring this is going
to be a video guide on the first things
to check when your engine does backfire
the first thing we're going to cover is
what causes a backfire when your engine
backfires it can do so in one of two
ways first and the most common way is
when the engine is running a small
explosion of unburned fuel is ignited
inside of the intake manifold causing a
loud bang which is what you hear in a
backfire this explosion can bend the
throttle actuator plate push the intake
gaskets outward creating a vacuum leak
and even blow apart plastic intake
manifolds when intake manifolds were
made of aluminum they could better
withstand this kind of problem this
occurrence can happen once or a few
times when the engine is under load or
it can happen continuously signaling a
mechanical failure which we'll go over
in the following repair the second kind
of problem will occur from the rear of
the vehicle's tailpipe which is a rich
fuel mixture problem that can happen
when the fuel delivery parts fail such
as an injector fuel pressure regulator
or intermittent ignition system failures
a backfire condition can also occur in
race cars using a turbocharger which is
normal because they push the field
through the engine which is an ignited
in the exhaust system we will cover the
primary occurrence of the engine under
load first this problem must be
corrected and cannot be neglected
because serious engine damage can occur
on the small side of things a simple
vacuum hose might be pushed off which is
an easy fix our step one is if you have
a check engine light any time you have
an engine that is backfiring the first
thing to do is check the check engine
light if no warning lights are on the
dash continue on with the sky if the
check engine light or service engine
soon light is on go ahead and scan the
computer for these trouble codes I have
a link in the description for a more
detailed video about that
this will help locate the system that is
having a problem and needs a repair
step two
checking fuel system pressure an intake
backfiring explosion can be caused by
the feel air mixture being too lean when
the engine is demanding power every
internal combustion engine runs on a
mixture of 14 to one which is 14 parts
air to one part fuel proper fuel
pressures needed to atomized the fuel
correctly when it leaves the fuel
injector to complete the burn process
the most common cause for this problem
is a weak fuel pump which cannot supply
the volume of fuel needed to the
injector to produce the power and the
proper spray pattern I have a link in
the description to a video that more
accurately goes over this problem the
fuel system pressure needs to be tested
in order to see if the fuel delivery
system is the problem and what's causing
your back pressure if your fuel system
pressure checks out continue on in the
sky
step number three service or replace the
mass air flow sensor your vehicle's
computer system monitors the air that
enters the engine via the mass airflow
sensor or MAF when the sensor
malfunctions due to addition called
coking the hot wire inside the sensor
becomes contaminated and will alter the
reader reading to the computer which
will create a lean mixture condition
that may or may not trigger the check
engine light the lean condition is
because the computer thinks there's less
air entering the engine than there
actually is less air means less fuel the
first step is to remove the mass airflow
sensor and clean it using carburetor
cleaner we have had better luck by
replacing the sensor because once this
condition happens the Hotwire can become
unresponsive in which case the sensor
needs to be replaced
rather than cleaned but if you do have a
the time to clean it and check and see
if this fixes your problem it is a good
step what we do recommend just replacing
the sensor entirely if this didn't fix
your problem continue on in our video
guide step number four is to check the
air intake boot or to the air intake
boot or tube transfers air from the mass
airflow sensor into the throttle
actuator and then into the engine if
there is a problem with these parts such
as a tear or a rip it will allow
unmetered air into the engine which the
computer will see via the oxygen sensor
which in turn will deliver less fuel
creating a lean condition check this
part for damage by removing it for
inspection and replace it if needed I
again I have a link in the description
to a more detailed video on that subject
go ahead and go check that out
if that didn't fix your problem go ahead
and continue in this guide step number
five check for vacuum leaks the engines
intake system depends on completely
being sealed and free from leaks if a
main vacuum hose such as the power brake
booster feed line has broken or falling
off it will cause a Leanback fire due to
additional air allowed into the intake
engine manifold this problem will be
accompanied by a high or low engine idle
and a harder to push brake pedal than
normal using a smoke machine or
carburetor cleaner you can check for a
vacuum leak and repair it to fix the
problem like
and I have a link in the description to
a more detailed video on the subject if
your problem is still not resolved
continue on the next thing we're going
to cover is repetitive backfire a
repetitive backfire is generated when
the engine is simply running at idle or
at cruising speed and can be in line
with the engine rpm a rhythmic popping
sound which is not as prominent as lean
under power backfires this next set of
problems will give you an idea of what
the causes could be generating this
condition step number six worn or
shortened spark plugs the engines
ignition system is triggered by an
electric driver which signals the
ignition coil when to fire by design the
resistance it takes to fire the coil via
the spark plugs is figured into the
system when the resistant becomes
excessive due to severely warm spark
plugs or a bag ignition coil it can
cause these drivers to malfunction at
which point they can crossfire into an
opposing cylinder either under power or
at idle this condition may or may not be
detected by the computer so the check
engine warning light may not come on
spark plugs should be changed at regular
interval intervals Platinum plugs should
be about 60,000 miles which may correct
this problem step number seven check the
camshaft a camshaft is used to open the
intake and exhaust valves of the
combustion chamber to allow intake air
in and the spent exhaust gases out if
the exhaust valve lobe becomes worn and
loses its lift the fire from the exhaust
gases are still left in the cylinder
which is released into the intake
manifold once the intake valve opens to
check for this condition first you must
remove the valve cover
after the valve covers have been removed
and with the ignition disabled also
known as the coils being off crank the
engine over and observe the intake and
exhaust valve operation opening and
closing also if the intake or exhaust
valves are not closing completely due to
a broken valve spring it will allow the
combustion gases to enter the intake
manifold much like a flat camshaft lobe
which we talked about earlier use a
flashlight and carefully check the valve
spring windings these Springs can break
at either the top middle or bottom of
the spring which can sometimes be
difficult to see a bent pushrod can also
cause the valve not to work properly by
pastrik ting the movement of the valve
while the valve cover is still remove
look at each of the push rods to see if
there is an obvious Bend to them this
can also be done by detecting poor
rocker arm movement while the engines
being cranked over now we're going to
talk about exhaust tailpipe backfire and
exhaust tailpipe backfire is caused by
an excessive amount of unburned fuel
remaining in the exhaust system or fresh
here being allowed to enter the system
which ignites a small amount of unburned
fuel step 1 is going to be trying to
detect an upstream exhaust leak if fresh
air is allowed to leak into the exhaust
system below ignite the unburned fuel
inside the system creating a popping
noise is difficult to think of because
most people think of the exhaust system
to be under constant pressure but this
is not true the system is fed with a
series of pressure and vacuum pulses
which are created by the exhaust valve
opening while the combustion charge is
being expelled into the system and the
valve closing this is where the vacuum
event is created by the pulse velocity
of the fresh air let into the system
this is why you can get a lean mixture
trouble code when there's an exhaust
system leak inspect the system and
repair any exhaust leaks present this
detection is done by looking for flat
black soot which is evidence of a leak
step 2 in this section is to check the
gulp valve on engines made from about
2001 and older there are sometimes
equipped with an air injection system
that is fed into the exhaust system when
the engine is
load this is to burn unspent fuel which
helps with the emission systems work
better
this system is fit with an air gulp
valve that acts like a one-way check
valve to allow air into the system when
the engine is under load this gol valve
is fitted to the exhaust manifold via a
large pipe or an individual port tubing
confederación with a rubber tube that
connects to an air pump when the valve
goes bad air is released into the system
at all times even during deceleration
which is then creating a backfire or a
popping due to the fresh air igniting
the unspent fuel most engines have one
or two of these valves for each exhaust
manifold to check these valves you must
remove them and try to blow through them
each way one direction is all it should
be allowed if air is blood in both
direction the valve is bad and should be
replaced thank you so much for watching
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