Details for 3766050.pdf

Swing and a miSfire for thiS honda CiviC’S engine diagnoSiS
it watching Perry Mason. In Latin,
it says “post hoc ergo propter hoc.”
That’s Latin for “Nuh uh, wasn’t
Sam’s fault!”

BY RAY MAGLIOZZI
Dear Car Talk:
I got gas from Sam’s and my 2001
Honda Civic started misfiring. I
changed the spark plugs and air
filter. I put HEET, gas treatment
and injector cleaner in the gas tank,
but the engine is still misfiring. — AJ
I got gas at Sam’s once, too, and I
haven’t eaten there since. There’s
something law students learn called
the “post hoc fallacy,” AJ. I learned

caused Y.

In your case, it’s less likely that the
misfiring was caused by getting
gas at Sam’s, and more likely that
it’s related to the fact that your car
is 18 years old. The first thing I’d
hope for is a bad ignition coil. If
the car is misfiring continuously
(for instance, if it’s misfiring at
idle) it’s easy to test for that. While
it’s running, try unplugging one
ignition coil at time. Each time you
remove a coil, the engine should run
worse. So, if you disconnect one coil
and nothing changes, that’s likely
the bad one.

The translation is actually “after
this, because of this.” And it’s
called a fallacy since lots of people
mistakenly assume that because
Event Y happened right after Event
X, then Event X must have caused
Event Y. But that’s not always true.
If you start dating your secretary
and your gutters start to leak, the
first event did not necessarily cause
the second event. But if you start
dating your secretary and then you
find yourself divorced, living in a You can test this further by replacing
washing machine box and grilling that particular coil. If the car then
squirrels under a bridge, then X runs perfectly, you’re all set. If it’s

still misfiring, then you could have a
valve that’s too tight in that cylinder,
or if it’s been too tight for a while,
you could have a valve that’s burned
out. Another possibility is that you
have a timing belt that jumped.
Check the coils first, AJ. And if you
end up solving the problem, we’ll
conclude that’s a direct result of
writing to us. Post Car Talk ergo
propter Car Talk.
***

Got a question about cars? Write to Ray
in care of King Features, 628 Virginia
Drive, Orlando, FL 32803, or email
by visiting the Car Talk website at
www.cartalk.com.
© 2019 by Ray Magliozzi and Doug
Berman

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