hey guys chrisfix here today we're going
to diagnose bad spark plug wires I'm
going to show you how to tell if a spark
plug wires bed some symptoms might be a
misfire in your engine you could be
getting bad fuel economy you're idling
is weird
it could be idling high or low there is
radio noise interference like you hear a
high-pitched squeal those are all
indicators of bed spark plug wires I'm
going to show you three different
methods the first method is just going
to be a water mist test and you're going
to do that at night the second method is
a visual inspection and the third method
is using a multimeter so we'll cut the
lights right now what you need is a
water bottle a spray bottle set to mist
you have your engine running so here
your spark plug wires this is where the
electronic distributor is and your spark
plug wires go into the spark plugs in
the cylinder heads what I'm going to do
I'm going to shut the light on the
camera and just take the spray bottle
just plain water and mist it and what
I'm going to look for our sparks sparks
mean that the spark plug wire is
shorting and arcing so you get the idea
now I'm going to shut the light off
right now I'm spraying on top of the
distributor cap area hopefully that
comes up on the camera now I'm moving
over to the passenger side wires
underneath where the wires meet the
spark plugs I don't see anything there
and now I'm moving to the driver's side
I don't know if you can see it sparking
in the back there but they're sparking
it's just like little flickers of light
and now I'm going to try underneath I
don't see anything underneath so you
just saw the water mist test and you saw
it did spark so there is arcing so I'm
going to show you the next way to tell
if a spark plug wire is bad the second
method is to visually inspect the spark
plug wires now this could be difficult
to do when it's in your car so you might
have to take them out and I have them
out just to show you make it really easy
for you to see so I have these spark
plug wires side-by-side what we're going
to look for were three different things
we're going to look for corrosion on the
metal pieces we're gonna look for any
burn marks and we're gonna look for any
cuts any cracks anything where there's
no insulation between the wire and the
outside that will cause problem so we
have a brand new wire here you can see
right next to the used wire and the idea
here is I want to show
you the difference the metal on both the
brand new one and the old one look the
same there's no corrosion that's a good
first step now we're going to look down
the spark plug wire and make sure
there's no cracks or burns and as we go
past when I check all sides it might
help to use some wd-40 to clean the
spark plug wire you just spray it on
there and use a paper towel to clean it
off you can see here here's some spots
where the insulation is worn down
because it was rubbing so that's no good
and the final thing is look for any
cracks a lot of times it'll crack near
the boot that goes right next to the
block because it's really hot there and
this actually looks pretty good you can
see there's a burn mark right there
that's no good I have an example of a
bad spark plug wire that has a bunch of
different things you can see this is
where the clip was it kind of dug in and
caused some problems there there's a
nice cut right there when you bend it it
really opens up and right behind the
crack you can see here there's a really
good burn mark and this thing is shot
we're going to replace the spark plug
wires I'll have a video at the end of
this video to show you how I did it but
again just for a summary you're looking
for little cuts little cracks anything
like that you're looking for burn marks
and you're looking for any corrosion
that's inside here or inside here so the
next method we're going to use test
spark plug wires is using a multimeter
we're going to put it on Ohm's and we're
going to check each wire so I'm going to
use old and new spark plug wires to show
you the difference I have a tape measure
and I'll explain why that's important
and I have an ohm meter this is actually
a multimeter has a bunch of different
functions what you want to do is look
for the horseshoe that's an Omega symbol
and you want to set it to 20,000 when
you make contact it tells you the
resistance of the wire so this is the
first test you want to do it you wanna
make sure it's working properly see how
it changes and then when you let go
break the contact it goes back to one so
we're using a tape measure because the
resistance of a wire is measured by foot
so on a normal spark plug wire you get
about five to eight thousand ohms of
resistance per foot now the newer spark
plug wires today that resistance could
go all the way down into the hundreds
here is the spark plug wire that just
showed you that has the burn marks and
the cuts in it this spark plug wire is
about 17 inches long I'm going to just
take one side here and make contact with
the metal and then take my other side
and in here there's a piece of metal as
well and make contact and you can see
that change
to five thousand four hundred ohms so
that's actually not too bad the problem
is right now the spark plugs bent and
you can see there's contact once I like
unbend it a little bit you can see I'm
moving the spark plug wire around it
loses contact inside so that means
there's a fault in here so sure maybe
this works some of the times but once it
gets moved around a little bit you lose
a connection in here and that's no good
so the spark plug wire is shot now I
have this long spark plug wire it's 32
inches long and here's the matching one
which is the same length and this is the
brand new one so I'm going to do the
brand new one first so you can see here
the brand new one is 1500 ohms
that's pretty good for a over two foot
wire so now I'm going to check the stock
wire that's old and see what that is and
we can see the old one is ten thousand
three hundred thirty three ohms so still
within spec but not as good as the new
spark plug wires so that's how you check
the continuity and ohms of a spark plug
wire so those are the three different
methods I have for you on checking your
spark plug wires hopefully this video
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