you have an engine MISFIRING problem? Here are a
few tips for you!
means one or two of your engine cylinders are not
firing. This will cause your engine to miss resulting
in a rough running engine.
are the symptoms:
shakes when idling
cannot let an engine miss (misfire) for a long
time. Sometimes, it will take your ignition module,
which will cause a NO START later.
are the types of MISFIRES?
misfire happens when the cylinder fail to fire
because of mechanical failure.
train failure if the cylinder valves are worn,
the cylinder looses compression. The same applies
if the piston rings get too small clearance causing
it also to loose compression. This kind of failure
is easy to check, using a compression tester.
Measure the cylinder compression of ALL the cylinders.
Anything below 100 PSI or below the norm or average
reading is an indication of a failing cylinder.
The only repairs you can do here is either pull
out the cylinder head or replace the engine.
misfires happens when your engine has a vacuum
this happens, your engine will have a rolling
miss. It is called rolling because unlike the
first one on top, your engine miss could travel
to any cylinder, whereas the first one is confined
to one or two cylinders. This is hard to diagnose
because the compression testing won’t help you.
The trick here is to find the vacuum leak usually
by spraying carb cleaner to suspected vacuum hoses
and gaskets. When done on idle, the RPM usually
change when the carb cleaner hits the vacuum leak.
misfires is almost similar to the second one above
except this one could be caused by ignition failure.
this engine miss will happen like a rolling misfire
because the weak spark could happen in any cylinder.
The most common fix on this is to check ignition
parts for proper readings.
misfires happens after your engine overheats (this
is also a mechanical failure).
this occurs, your cylinder head gaskets has a
crack. This will cause your cylinder to lose compression
just like the first case above. The same thing
happens when the cylinder head itself gets warped
because of the heat. A compression tester can
test both of these problems.
problem MISFIRE TIPS:
One of the leading causes of rolling misfires
is cause by EGR failure. As you remember, EGR
is a devise that introduces exhaust gases to your
intake to make your engine run cooler and reduce
emission. The EGR valve, which opens and acts
like a door for the exhaust gases does this. However,
the EGR is stuck open all the time, your engine
will miss. It must be done on acceleration only
but not on idle.
are some misfire fixes shown on ATS database:
GM engine EGR tips:
check the egr:
make sure it will open and hold vacuum with the
eng. off. Next start the engine, it should slam
closed. If it does not, then it is bad. Also,
it is a negative feed back EGR valve and requires
eng vacuum to regulate how much it opens. To know
if was not regulating, the egr would close, but
digital (electric) EGR fixes:
fix, was electric solenoid for EGR valve, it has
a dump in the top of it (has a filter over it)and
it was holding the vac on so when the engine was
started cold it already had EGR valve open enough
to cause minor over fueling (vac leak through egr
valve)that the long decel period customer went through
to second stop sign must be enough to flood engine
just enough to kill it and not enough to make it
start like it was rich”
“The fix turned out to be the EGR valve - it was
open enough to completely mess up the engine when
cold but the engine ran okay when warm.”
F150 EGR testing:
check this, take your vacuum pump and open the
EGR valve, The engine should stumble like it is
going dead and then recover and run fairly well.
If this does not happen, the EGR passages are
stucked up. However don't jump the gun too quick,
remember the DPFE (EVR) solenoid still gives it
a share of problems too”.
Have you seen ATS
newest SECRET tool?
closer look at the injector $5 Noid Tester: