How To Fix A P0300 Random Cylinder Misfire

How To Fix A P0300 Random Cylinder Misfire


All right, today i’m gonna be diagnosing p0300
which is a random
cylinder misfire on this buick
Basically a problem with a p0300 random cylinder misfire is it doesn’t tell you
It doesn’t identify, which cylinders are actually misfiring, so i’m gonna show. You how to check these, with i’m gonna show
You, how to check the misfires with a scan tool, and also how to manually test to find out, which cylinder is actually misfiring so
You can, repair it i’m working on a six cylinder here so basically out of the six cylinders, we need to figure out
Which one of the ones are misfiring because the colored we’re getting, isn’t identifying the actual misfire it’s just a random misfire so
Let’s just double-check that
trouble codes here
and as you can see
We have the p0300 engine misfire detected
So that doesn’t really give us a whole lot of information there it just tells us that, we have a misfire
So i’m gonna go into
the tech 2 here
we’re gonna go into special functions and see if
Miss paragraph so, we got a. Misfire graph here and hopefully this this is going to identify, which cylinders are misfiring
so i’ll go ahead and open that up and
All right this thing up and it is definitely misfire i can, feel it and as you can see we got cylinder six
And cylinder three are misfiring so on this particular vehicle it’s got three ignition coils two coils that run
Or three ignition coils, each coil runs two cylinders so it’s a six
Cylinder it’s got three coils, each coil runs two cylinders so first thing i’m going to check up i’m gonna go under the hood
and see if
Cylinder six and three are
Running, off the same ignition coil, which
There’s a good possibility of the our clothes are pretty common on these but let’s go ahead and go
Underneath the hood here and dig into this thing a little deeper now that we’ve identified
Which cylinders are actually misfiring on this one it’s going to be six and three
Okay, and here we have cylinder six?
And cylinder three and as you can see these cylinders are firing off the same ignition coil so
I’m just going to go ahead and start this thing up and see if we have spark coming out of the six and three
ignition coil
And to, do that all i’m going to do, is take pair of pliers and pull the wires off
and as you can see there we got a nice strong spark coming off the cylinder
and so the three, we have nothing and
cylinder two, we have nothing
So at this point
and you want a nice strong spark like, you can see
Yeah, pull out that one now, and actually almost all the motors so but so we definitely have
No, spark coming out six. And three so on that’s what’s causing our misfire
So at this point what we’re gonna have to do is our share, gonna swap these coils around
because i
Mean i’ll first
First thought you would think that it’s a
Bad ignition coil but on this motor and a mesa is actually the ignition module so each one of these coils has a driver
That the ignition module powers
So to verify
Whether or not the ignition module is bad in this or if the ignition coil is bad
We’re going to have to i’m gonna go ahead and swap
Swap it with the
Cylinder to five coil, which we know is working properly?
Just to make sure the driver in the ignition mazal module hasn’t failed
Also, another quick tip is when you’re pulling, these, spark plug wires off to check for spark
If you’re, using a pair of pliers and you, don’t want to shock yourself a good, way to avoid, that is just take a?
Take a little jumper and connect it from your pliers to a ground
source and
it’s that
ignition spark
Transference to the pliers it’s just gonna read redirects rate to ground so you, won’t get shocked
also if you’re, wearing rubber gloves that will help and
Before you start the motor you just want to make sure the spark wires themselves you know
You’ve already loosened up, along up a little so you, don’t have to tug hard, on with the pliers because you
Don’t want it’ll cause any damage to him
So now, what i’m gonna do i got both these loosened up on this motor it’s just a, five point five millimeter
Socket i’m gonna, swap the wires around and
I’m gonna, swap the coils
i’ll also leave a link in the video description below to
Tune up stuff you can, buy on amazon i find that the cheapest and the fastest for shipping
Yeah, and underneath these coils is actually two, little prongs that sticking there from the ignition module that actually drives the coils
so basically by switching these like i said we’re gonna be
Testing to make sure the ignition module is driving the coil properly
So let’s fire we know for sure we had no spark on so under six and three which is causing the p0300
random cylinder misfire
so we’ve narrowed it down to what cylinders it is
We’ve identified it was no spark coming out of that coil
And now, we have swapped the coils to make sure that our ignition module is right so i got these vicious
Well swap i got the wires swapped around we’re gonna go ahead, and fire this back up and we’re gonna use the same test
to, see if we have spark
All right so we’ve got no spark now on the
On this coil, we just walked, and the one that, we did have sparked didn’t have spotted before is now sparking
So in this case the actual driver and this ignition module has failed so our coil is good
Under the first assumption you would have suspected that this coil, was bad but now. By swapping this
we have verified and now that the ignition module and this is actually bad and that’s what’s causing our p0300
Now if you’re getting a p0300
and you can’t
Identify, which cylinder is misfiring with a scan tool or other ways, these are the best
Ways just to come out and you know start pulling pulling wires and see which cylinder is affected by you pulling those admission wires off
in this case it was pretty obvious to us that, we had no spark out of six and three and
you know we’re, we were able to narrow down relatively quick
Now in order to?
Repair, this vehicle or, ask, well all three of these coils off and replace the module that sits down underneath it now probably
Also, gonna replace the ignition coil
Only, because typically i mean there’s a reason, why, these parts fail
the
This, ignition coil, could be shorting i mean it could have, some razak, high resistance and the primary windings and
over time it could
Have just stressed that that admission module so i mean inspect the rest of the ignition components on this vehicle
Spark plug wires spark plugs themselves and if those all look, good we’re probably
gonna, we’re gonna have to replace the ignition module and we’re probably, gonna be end up replacing at least that one
ignition coil
Buy-down, what’s actually failed in our case here is the ignition module
Once again thanks for watching hope, this video
Was helpful on p0300 random cylinder misfire be sure to hit the thumbs up button, below
And subscribe to my channel says, was helpful thanks flat rate mechanic


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