300M misfire code P0302 -> no coil codes, no injector codes?

Just today my '00 300M started running rough. Most noticable at idle
- like a cylinder not firing.

Engine light came on.

After parking it for a while, and starting it, it idles rough, but no
engine light. Engine light only comes on if I drive it a little.

Codes displayed on odometer are P1684 and P0302.

The 1684 is a battery disconnect code (it has the original battery,
which hasn't been disconnected for years - if ever, so perhaps this is
an indication of a weak battery - although it turns the engine over
just fine when cold). The 1684 code is said to not be responsible for
the check-engine light.

The P0302 code (if I'm right) indicates misfire in cylinder 2. This
website:

http://www.aa1car.com/library/copign.htm

says that I should also expect to see either a coil code that
corresponds to the same cylinder (P0351 to P0358) or a code that
indicates an open or shorted injector in that cylinder (P0201 to
P0208). I don't see any of those codes. Just 1684 and 0302.

Might this set of conditions represent just a bad plug then? (orginal
plugs).

Car is exactly 8 years old tommorrow - bought it new back on Nov 1,
1999.

Comments?

Answers?

Recommendations for aftermarket plug brand (I might as well start
there) ?

Have never taken off a coil pack before - any special tools, or is it
self-evident?

Which one is cylinder 2?

"MoPar Man" > wrote in message
...
> Just today my '00 300M started running rough. Most noticable at idle
> - like a cylinder not firing.
>
> Engine light came on.
>
> After parking it for a while, and starting it, it idles rough, but no
> engine light. Engine light only comes on if I drive it a little.
>
> Codes displayed on odometer are P1684 and P0302.
>
> The 1684 is a battery disconnect code (it has the original battery,
> which hasn't been disconnected for years - if ever, so perhaps this is
> an indication of a weak battery - although it turns the engine over
> just fine when cold). The 1684 code is said to not be responsible for
> the check-engine light.
>
> The P0302 code (if I'm right) indicates misfire in cylinder 2. This
> website:
>
> http://www.aa1car.com/library/copign.htm
>
> says that I should also expect to see either a coil code that
> corresponds to the same cylinder (P0351 to P0358) or a code that
> indicates an open or shorted injector in that cylinder (P0201 to
> P0208). I don't see any of those codes. Just 1684 and 0302.
>
> Might this set of conditions represent just a bad plug then? (orginal
> plugs).
>
> Car is exactly 8 years old tommorrow - bought it new back on Nov 1,
> 1999.
>
> Comments?
>
> Answers?
>
> Recommendations for aftermarket plug brand (I might as well start
> there) ?
>
> Have never taken off a coil pack before - any special tools, or is it
> self-evident?
>
> Which one is cylinder 2?

Start with replacing the plugs if you gonna take a pot shot at it. If it
didn't take care of it the next thing you can do is swap coils from one
cylinder to another to see if the misfire switches, if it does...replace the
effected coil. you don't specify what engine, number 2 cyl on the 3.2/3.5 is
on the drivers side front. the 2.7 is on the passenger side front.

Glenn Beasley
Chrysler Tech

maxpower wrote:
> "MoPar Man" > wrote in message
> ...
>
>>Just today my '00 300M started running rough. Most noticable at idle
>>- like a cylinder not firing.
>>
>>Engine light came on.
>>
>>After parking it for a while, and starting it, it idles rough, but no
>>engine light. Engine light only comes on if I drive it a little.
>>
>>Codes displayed on odometer are P1684 and P0302.
>>
>>The 1684 is a battery disconnect code (it has the original battery,
>>which hasn't been disconnected for years - if ever, so perhaps this is
>>an indication of a weak battery - although it turns the engine over
>>just fine when cold). The 1684 code is said to not be responsible for
>>the check-engine light.
>>
>>The P0302 code (if I'm right) indicates misfire in cylinder 2. This
>>website:
>>
>>http://www.aa1car.com/library/copign.htm
>>
>>says that I should also expect to see either a coil code that
>>corresponds to the same cylinder (P0351 to P0358) or a code that
>>indicates an open or shorted injector in that cylinder (P0201 to
>>P0208). I don't see any of those codes. Just 1684 and 0302.
>>
>>Might this set of conditions represent just a bad plug then? (orginal
>>plugs).
>>
>>Car is exactly 8 years old tommorrow - bought it new back on Nov 1,
>>1999.
>>
>>Comments?
>>
>>Answers?
>>
>>Recommendations for aftermarket plug brand (I might as well start
>>there) ?
>>
>>Have never taken off a coil pack before - any special tools, or is it
>>self-evident?

Coil screw heads will either be torx #25 or #27 depending on engine.
They can be frozen and difficult to remove without stripping the heads.
Get torx bit straight and fully seated. Penetrating oil soak ahead of
time wouldn't hurt. Also try good tap directly on head of the screw
with a hammer to help break them loose before trying to remove.

>>Which one is cylinder 2?
>
>
> Start with replacing the plugs if you gonna take a pot shot at it. If it
> didn't take care of it the next thing you can do is swap coils from one
> cylinder to another to see if the misfire switches, if it does...replace the
> effected coil. you don't specify what engine, number 2 cyl on the 3.2/3.5 is
> on the drivers side front. the 2.7 is on the passenger side front.
>
> Glenn Beasley
> Chrysler Tech

Glenn - Every piece of documentation I have says #1 cyl. is front
passenger side for all three engines (3.2, 3.5, 2.7) and therefore #2 is
front drive's side. Can you check your documentation and post back?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

8 years on the original battery?

Replace the battery since it is on borrowed time. A bad battery with low
operating voltage can mess up the sensor readings and computer controls.
I'd see how it runs after that before trying anything else.

Bob

"MoPar Man" > wrote in message
...
> Just today my '00 300M started running rough. Most noticable at idle
> - like a cylinder not firing.
>
> Engine light came on.
>
> After parking it for a while, and starting it, it idles rough, but no
> engine light. Engine light only comes on if I drive it a little.
>
> Codes displayed on odometer are P1684 and P0302.
>
> The 1684 is a battery disconnect code (it has the original battery,
> which hasn't been disconnected for years - if ever, so perhaps this is
> an indication of a weak battery - although it turns the engine over
> just fine when cold). The 1684 code is said to not be responsible for
> the check-engine light.
>
> The P0302 code (if I'm right) indicates misfire in cylinder 2. This
> website:
>
> http://www.aa1car.com/library/copign.htm
>
> says that I should also expect to see either a coil code that
> corresponds to the same cylinder (P0351 to P0358) or a code that
> indicates an open or shorted injector in that cylinder (P0201 to
> P0208). I don't see any of those codes. Just 1684 and 0302.
>
> Might this set of conditions represent just a bad plug then? (orginal
> plugs).
>
> Car is exactly 8 years old tommorrow - bought it new back on Nov 1,
> 1999.
>
> Comments?
>
> Answers?
>
> Recommendations for aftermarket plug brand (I might as well start
> there) ?
>
> Have never taken off a coil pack before - any special tools, or is it
> self-evident?
>
> Which one is cylinder 2?

"Bill Putney" > wrote in message
...
> maxpower wrote:
> > "MoPar Man" > wrote in message
> > ...
> >
> >>Just today my '00 300M started running rough. Most noticable at idle
> >>- like a cylinder not firing.
> >>
> >>Engine light came on.
> >>
> >>After parking it for a while, and starting it, it idles rough, but no
> >>engine light. Engine light only comes on if I drive it a little.
> >>
> >>Codes displayed on odometer are P1684 and P0302.
> >>
> >>The 1684 is a battery disconnect code (it has the original battery,
> >>which hasn't been disconnected for years - if ever, so perhaps this is
> >>an indication of a weak battery - although it turns the engine over
> >>just fine when cold). The 1684 code is said to not be responsible for
> >>the check-engine light.
> >>
> >>The P0302 code (if I'm right) indicates misfire in cylinder 2. This
> >>website:
> >>
> >>http://www.aa1car.com/library/copign.htm
> >>
> >>says that I should also expect to see either a coil code that
> >>corresponds to the same cylinder (P0351 to P0358) or a code that
> >>indicates an open or shorted injector in that cylinder (P0201 to
> >>P0208). I don't see any of those codes. Just 1684 and 0302.
> >>
> >>Might this set of conditions represent just a bad plug then? (orginal
> >>plugs).
> >>
> >>Car is exactly 8 years old tommorrow - bought it new back on Nov 1,
> >>1999.
> >>
> >>Comments?
> >>
> >>Answers?
> >>
> >>Recommendations for aftermarket plug brand (I might as well start
> >>there) ?
> >>
> >>Have never taken off a coil pack before - any special tools, or is it
> >>self-evident?
>
> Coil screw heads will either be torx #25 or #27 depending on engine.
> They can be frozen and difficult to remove without stripping the heads.
> Get torx bit straight and fully seated. Penetrating oil soak ahead of
> time wouldn't hurt. Also try good tap directly on head of the screw
> with a hammer to help break them loose before trying to remove.
>
> >>Which one is cylinder 2?
> >
> >
> > Start with replacing the plugs if you gonna take a pot shot at it. If it
> > didn't take care of it the next thing you can do is swap coils from one
> > cylinder to another to see if the misfire switches, if it does...replace
the
> > effected coil. you don't specify what engine, number 2 cyl on the
3.2/3.5 is
> > on the drivers side front. the 2.7 is on the passenger side front.
> >
> > Glenn Beasley
> > Chrysler Tech
>
> Glenn - Every piece of documentation I have says #1 cyl. is front
> passenger side for all three engines (3.2, 3.5, 2.7) and therefore #2 is
> front drive's side. Can you check your documentation and post back?
>
> Bill Putney
> (To reply by e-mail, replace the last letter of the alphabet in my
> address with the letter 'x')

Your correct, I was thinking of the transverse set up as in a Sebring
Convertible 2.7 which would put the #2 plug at the passenger side front.
Must be an old age thing setting in

maxpower wrote:

> > Codes displayed on odometer are P1684 and P0302.

> Start with replacing the plugs if you gonna take a pot shot at
> it. If it didn't take care of it the next thing you can do is
> swap coils from one cylinder to another to see if the misfire
> switches, if it does...replace the effected coil.

The coils came off easy, and so did the plugs.

I started by putting a new plug into #2 (front driver side). Original
plug was dirty (8 years, 72k miles). Replacement was exact same kind
(champion). I didn't gap the new plug (do you still gap plugs these
days?).

That didn't work - it still idled rough.

I then replaced plug #1 (front passenger side) and swapped the coils
between 1 and 2. (original plug 1 looked to be in the same shape as
#2).

That didn't work - it still idled rough.

Codes still say 1684 and 0302 (still indicating the problem is with
cylinder 2).

> you don't specify what engine,

3.5L

So at this point, how does the computer know that the problem is
cylinder 2? What other sensor could tell the computer that #2 is the
problem? If it was the injector, then why no injector codes?

Regarding the battery -

I did have to get a replacement ignition key and fob to replace a
stolen one (about 2 weeks ago). The dealer reprogrammed the car to
accept the new key and fob and reject the stolen ones. Would that
have required disconnecting the battery?

MoPar Man wrote:
> maxpower wrote:
>
>
>>>Codes displayed on odometer are P1684 and P0302.
>
>
>>Start with replacing the plugs if you gonna take a pot shot at
>>it. If it didn't take care of it the next thing you can do is
>>swap coils from one cylinder to another to see if the misfire
>>switches, if it does...replace the effected coil.
>
>
> The coils came off easy, and so did the plugs.
>
> I started by putting a new plug into #2 (front driver side). Original
> plug was dirty (8 years, 72k miles). Replacement was exact same kind
> (champion). I didn't gap the new plug (do you still gap plugs these
> days?).
>
> That didn't work - it still idled rough.
>
> I then replaced plug #1 (front passenger side) and swapped the coils
> between 1 and 2. (original plug 1 looked to be in the same shape as
> #2).
>
> That didn't work - it still idled rough.
>
> Codes still say 1684 and 0302 (still indicating the problem is with
> cylinder 2).
>
>
>>you don't specify what engine,
>
>
> 3.5L
>
> So at this point, how does the computer know that the problem is
> cylinder 2? What other sensor could tell the computer that #2 is the
> problem? If it was the injector, then why no injector codes?
>
> Regarding the battery -
>
> I did have to get a replacement ignition key and fob to replace a
> stolen one (about 2 weeks ago). The dealer reprogrammed the car to
> accept the new key and fob and reject the stolen ones. Would that
> have required disconnecting the battery?

Did you reset the codes?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

Bill Putney wrote:

> Did you reset the codes?

No - how do you do that?

PS: Cylinder 2 is front driver side, with front meaning closest to
the front of the car - yes?

Bill Putney wrote:

> Did you reset the codes?

Hypothetically, let's say my problem is a bad #2 coil. Say that's
what's causing the 0302 code.

So I swap coil #2 with coil #1.

But I don't reset the codes.

So I start the car, car idles rough, and the check engine light goes
on.

I then do another read of the codes.

Because I didn't reset the codes, I guess I'll still see 0302. But if
cylinder #1 now has the bad coil, shouldn't I now see code 0301 ???

BTW, is there any way to reset the codes other than disconnecting the
battery?

"MoPar Man" > wrote in message
...
> maxpower wrote:
>
>> > Codes displayed on odometer are P1684 and P0302.
>
>> Start with replacing the plugs if you gonna take a pot shot at
>> it. If it didn't take care of it the next thing you can do is
>> swap coils from one cylinder to another to see if the misfire
>> switches, if it does...replace the effected coil.
>
> The coils came off easy, and so did the plugs.
>
> I started by putting a new plug into #2 (front driver side). Original
> plug was dirty (8 years, 72k miles). Replacement was exact same kind
> (champion). I didn't gap the new plug (do you still gap plugs these
> days?).

Yes. Plugs still get gapped unless they are platinum tipped.


>
> That didn't work - it still idled rough.


It may help if you replace all the plugs at that mileage.


>
> I then replaced plug #1 (front passenger side) and swapped the coils
> between 1 and 2. (original plug 1 looked to be in the same shape as
> #2).
>
> That didn't work - it still idled rough.
>
> Codes still say 1684 and 0302 (still indicating the problem is with
> cylinder 2).
>
>> you don't specify what engine,
>
> 3.5L
>
> So at this point, how does the computer know that the problem is
> cylinder 2? What other sensor could tell the computer that #2 is the
> problem? If it was the injector, then why no injector codes?


When the coil fires for cyl #2 the PCM expects to see a jump in cranshaft
speed when cyl #2 fires. It reads crankshaft speed via the crank sensor. If
cyl #2 doesn't fire the PCM sees no increase in crank speed and sets a code.
It takes more than a single misfire to set a code.

If it was an electrical problem with the injector the PCM would be able to
pick that up and set a code. If it was a mechanical problem, such as a
plugged injector, the PCM would not be able to sense that.


>
> Regarding the battery -
>
> I did have to get a replacement ignition key and fob to replace a
> stolen one (about 2 weeks ago). The dealer reprogrammed the car to
> accept the new key and fob and reject the stolen ones. Would that
> have required disconnecting the battery?