OBD Code P0304

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wabbitslayer - 22 Mar 2006 14:42 GMT

OK, last night on the way home from work I noticed
surging/stumbling/something generally not right between 1500-2000 rpm.
I Went to WOT a time or two, both times the check engine light would flash a
time or two right after then go out. I eased it home, right before I got
there the light came on and stayed on. Took it by autozone a minute ago,
their scanner showed code P0304; of course, all the guy could tell me was
that cylinder 4 was misfiring, that it could be plugs, coil pack, wires,
etc....nothing that I couldn't guess for myself.

Google search only turned up the following info:

A code P0304 may mean that one or more of the following has happened:

Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer

I've got 53k miles...I'm guessing it's time for plugs, although the dealer
says 60k.
Guesses, anyone, before I either start throwing on parts or bend over and go
to the dealer?

Wabbitslayer

01 GT vert

Service Engine Soon Light---Operational

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Backyard Mechanic - 22 Mar 2006 15:09 GMT

> Took it by
> autozone a minute ago, their scanner showed code P0304; of course, all
> the guy could tell me was that cylinder 4 was misfiring, that it could
> be plugs, coil pack, wires, etc....nothing that I couldn't guess for
> myself.

Well? If he could just lean over and yank off the offending part, he
wouldnt be working there would he?

> Google search only turned up the following info:
>
> A code P0304 may mean that one or more of the following has happened:

Gonna separate out the possibilities,
Ignition, direct effect:

> Faulty spark plug or wire
> Faulty coil (pack)

> Defective computer

- that would be a weak injector driver, I would check ign wiring first

> Faulty fuel injector

- obviously, see below

> Burned exhaust valve
> Poor compression

- easily found with cyl leak-down test

From the "Stray quark ripped through my PCM and damaged a bit on the #4
injector driver department":

> Faulty catalytic converter(s)

discard, unless you consider "looks as if"

> Running out of fuel

> I've got 53k miles...I'm guessing it's time for plugs, although the
> dealer says 60k.
> Guesses, anyone, before I either start throwing on parts or bend over
> and go to the dealer?

First do a search on the alt.autos.ford and this group looking for
similar, IIRC likely to be a boot... or maybe a coil pack

Second: the old trick of analysing plugs is still valid, pull # 4 and a
couple others from both banks and compare them (LABEL THEM!)
- If you have a bad injector, O2 sensing will cause other plugs in bank
to show over compensation

Gee, I cut the O2 sensor and forgot to paste it... well, if it's faulty
then all the plugs on that side will show too lean or too rich

Signature

Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!

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wabbitslayer - 24 Mar 2006 03:08 GMT

well, looks like saturday morning I'll change plugs...about time for it
anyway,
if it's not the plug, they all needed changing anyway.

Although you should have seen me looking for the spark plugs on the sides of
the heads...
I even thought for a second, since I can't even see them from up top, the
best way is probably
to remove the wheel on each side and go in with a long extension....and
then....DOH!

(I know...I know...what a dumbass)

Wabbitslayer
01 GT vert

> First do a search on the alt.autos.ford and this group looking for
> similar, IIRC likely to be a boot... or maybe a coil pack
[quoted text clipped - 3 lines]
> - If you have a bad injector, O2 sensing will cause other plugs in bank
> to show over compensation

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Backyard Mechanic - 24 Mar 2006 04:01 GMT

> well, looks like saturday morning I'll change plugs...about time for
> it anyway,
[quoted text clipped - 8 lines]
>
> (I know...I know...what a dumbass)

Hey... about every other day, i cant find my keys.. and I KNOW what they
look like.

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Yeh, I'm a Krusty old Geezer, ......

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