Carl wrote:
> Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three
> coil packs.

Some rails can develop internal leaks that cause misfire. If you can, try
swapping packs and see if the problem moves. If it moves, it's the pack.
If it doesn't move, it could be the coil rail.

If you have a good rpm gauge or ears you can try this.
With the engine running, disconnect the injectors one
at a time (just one at any one time though) and listen.
There should be exactly the same drop in rpm. If you lift
#3 and there is little drop then the injector or the feed
to that injector might be bad. A mechanic stethescope placed
on each injector will also give you a clue as to how they
are working. They should have a clanging sound and not
a dull thunk.

Also remember, with coil rails and packs, plugs fire in pairs.
I think this is the correct pairing. don't have the schematic
to look at.

1 5 3 6 2 4
1 6
5 2
3 4


--
DougW

 

Carl wrote:
> Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three
> coil packs.

Some rails can develop internal leaks that cause misfire. If you can, try
swapping packs and see if the problem moves. If it moves, it's the pack.
If it doesn't move, it could be the coil rail.

If you have a good rpm gauge or ears you can try this.
With the engine running, disconnect the injectors one
at a time (just one at any one time though) and listen.
There should be exactly the same drop in rpm. If you lift
#3 and there is little drop then the injector or the feed
to that injector might be bad. A mechanic stethescope placed
on each injector will also give you a clue as to how they
are working. They should have a clanging sound and not
a dull thunk.

Also remember, with coil rails and packs, plugs fire in pairs.
I think this is the correct pairing. don't have the schematic
to look at.

1 5 3 6 2 4
1 6
5 2
3 4


--
DougW

 

So, one of the coils is bad.





"Carl" <carlsaiyed@hotmailREMOVE.com> wrote in message
news:bdqdnb4NANz57QHYnZ2dnUVZ_tOmnZ2d@comcast.com. ..
> Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three coil
> packs.
>
> Carl
>
>
> "Jeff Strickland" <crwlr@yahoo.com> wrote in message
> news:OfidnY5u3NmnmQHYnZ2dnUVZ_h6jnZ2d@ez2.net...
>> With a misfire, I'd be looking at the plug wires or coil. I'd check plug
>> wires if there was a distributor, or I'd look at the coil if there was a
>> separate coil for each cylinder, or a coil for every two cylinders.
>>
>>
>>
>> "01XJ" <adam.tsacoumangos@gmail.com> wrote in message
>> news:1167779855.090317.153570@v33g2000cwv.googlegr oups.com...
>>>I just started experiencing a rough idle on my 2001 Cherokee (78k
>>> miles). My engine light went on a little after that with the P0303
>>> code. I just replaced the spark plugs, but that didn't help anything.
>>> I was
>>> thinking about changing the ignition coil or fuel injector. One other
>>> possibility I was
>>> thinking was checking the cylinder compression (maybe a gasket leak?).
>>> Anyone have any suggestions?
>>>
>>
>
>

 

So, one of the coils is bad.





"Carl" <carlsaiyed@hotmailREMOVE.com> wrote in message
news:bdqdnb4NANz57QHYnZ2dnUVZ_tOmnZ2d@comcast.com. ..
> Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three coil
> packs.
>
> Carl
>
>
> "Jeff Strickland" <crwlr@yahoo.com> wrote in message
> news:OfidnY5u3NmnmQHYnZ2dnUVZ_h6jnZ2d@ez2.net...
>> With a misfire, I'd be looking at the plug wires or coil. I'd check plug
>> wires if there was a distributor, or I'd look at the coil if there was a
>> separate coil for each cylinder, or a coil for every two cylinders.
>>
>>
>>
>> "01XJ" <adam.tsacoumangos@gmail.com> wrote in message
>> news:1167779855.090317.153570@v33g2000cwv.googlegr oups.com...
>>>I just started experiencing a rough idle on my 2001 Cherokee (78k
>>> miles). My engine light went on a little after that with the P0303
>>> code. I just replaced the spark plugs, but that didn't help anything.
>>> I was
>>> thinking about changing the ignition coil or fuel injector. One other
>>> possibility I was
>>> thinking was checking the cylinder compression (maybe a gasket leak?).
>>> Anyone have any suggestions?
>>>
>>
>
>

 

So, one of the coils is bad.





"Carl" <carlsaiyed@hotmailREMOVE.com> wrote in message
news:bdqdnb4NANz57QHYnZ2dnUVZ_tOmnZ2d@comcast.com. ..
> Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three coil
> packs.
>
> Carl
>
>
> "Jeff Strickland" <crwlr@yahoo.com> wrote in message
> news:OfidnY5u3NmnmQHYnZ2dnUVZ_h6jnZ2d@ez2.net...
>> With a misfire, I'd be looking at the plug wires or coil. I'd check plug
>> wires if there was a distributor, or I'd look at the coil if there was a
>> separate coil for each cylinder, or a coil for every two cylinders.
>>
>>
>>
>> "01XJ" <adam.tsacoumangos@gmail.com> wrote in message
>> news:1167779855.090317.153570@v33g2000cwv.googlegr oups.com...
>>>I just started experiencing a rough idle on my 2001 Cherokee (78k
>>> miles). My engine light went on a little after that with the P0303
>>> code. I just replaced the spark plugs, but that didn't help anything.
>>> I was
>>> thinking about changing the ignition coil or fuel injector. One other
>>> possibility I was
>>> thinking was checking the cylinder compression (maybe a gasket leak?).
>>> Anyone have any suggestions?
>>>
>>
>
>

 

Or it's electronic plug and socket are dirty.....

Mike

Jeff Strickland wrote:
>
> So, one of the coils is bad.
>
> "Carl" <carlsaiyed@hotmailREMOVE.com> wrote in message
> news:bdqdnb4NANz57QHYnZ2dnUVZ_tOmnZ2d@comcast.com. ..
> > Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three coil
> > packs.
> >
> > Carl
> >
> >
> > "Jeff Strickland" <crwlr@yahoo.com> wrote in message
> > news:OfidnY5u3NmnmQHYnZ2dnUVZ_h6jnZ2d@ez2.net...
> >> With a misfire, I'd be looking at the plug wires or coil. I'd check plug
> >> wires if there was a distributor, or I'd look at the coil if there was a
> >> separate coil for each cylinder, or a coil for every two cylinders.
> >>
> >>
> >>
> >> "01XJ" <adam.tsacoumangos@gmail.com> wrote in message
> >> news:1167779855.090317.153570@v33g2000cwv.googlegr oups.com...
> >>>I just started experiencing a rough idle on my 2001 Cherokee (78k
> >>> miles). My engine light went on a little after that with the P0303
> >>> code. I just replaced the spark plugs, but that didn't help anything.
> >>> I was
> >>> thinking about changing the ignition coil or fuel injector. One other
> >>> possibility I was
> >>> thinking was checking the cylinder compression (maybe a gasket leak?).
> >>> Anyone have any suggestions?
> >>>
> >>
> >
> >

 

Or it's electronic plug and socket are dirty.....

Mike

Jeff Strickland wrote:
>
> So, one of the coils is bad.
>
> "Carl" <carlsaiyed@hotmailREMOVE.com> wrote in message
> news:bdqdnb4NANz57QHYnZ2dnUVZ_tOmnZ2d@comcast.com. ..
> > Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three coil
> > packs.
> >
> > Carl
> >
> >
> > "Jeff Strickland" <crwlr@yahoo.com> wrote in message
> > news:OfidnY5u3NmnmQHYnZ2dnUVZ_h6jnZ2d@ez2.net...
> >> With a misfire, I'd be looking at the plug wires or coil. I'd check plug
> >> wires if there was a distributor, or I'd look at the coil if there was a
> >> separate coil for each cylinder, or a coil for every two cylinders.
> >>
> >>
> >>
> >> "01XJ" <adam.tsacoumangos@gmail.com> wrote in message
> >> news:1167779855.090317.153570@v33g2000cwv.googlegr oups.com...
> >>>I just started experiencing a rough idle on my 2001 Cherokee (78k
> >>> miles). My engine light went on a little after that with the P0303
> >>> code. I just replaced the spark plugs, but that didn't help anything.
> >>> I was
> >>> thinking about changing the ignition coil or fuel injector. One other
> >>> possibility I was
> >>> thinking was checking the cylinder compression (maybe a gasket leak?).
> >>> Anyone have any suggestions?
> >>>
> >>
> >
> >

 

Or it's electronic plug and socket are dirty.....

Mike

Jeff Strickland wrote:
>
> So, one of the coils is bad.
>
> "Carl" <carlsaiyed@hotmailREMOVE.com> wrote in message
> news:bdqdnb4NANz57QHYnZ2dnUVZ_tOmnZ2d@comcast.com. ..
> > Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three coil
> > packs.
> >
> > Carl
> >
> >
> > "Jeff Strickland" <crwlr@yahoo.com> wrote in message
> > news:OfidnY5u3NmnmQHYnZ2dnUVZ_h6jnZ2d@ez2.net...
> >> With a misfire, I'd be looking at the plug wires or coil. I'd check plug
> >> wires if there was a distributor, or I'd look at the coil if there was a
> >> separate coil for each cylinder, or a coil for every two cylinders.
> >>
> >>
> >>
> >> "01XJ" <adam.tsacoumangos@gmail.com> wrote in message
> >> news:1167779855.090317.153570@v33g2000cwv.googlegr oups.com...
> >>>I just started experiencing a rough idle on my 2001 Cherokee (78k
> >>> miles). My engine light went on a little after that with the P0303
> >>> code. I just replaced the spark plugs, but that didn't help anything.
> >>> I was
> >>> thinking about changing the ignition coil or fuel injector. One other
> >>> possibility I was
> >>> thinking was checking the cylinder compression (maybe a gasket leak?).
> >>> Anyone have any suggestions?
> >>>
> >>
> >
> >

 

There is only one plug, at the rear of coil rail. Three coil packs are on
the rail.

Carl


"Mike Romain" <romainm@sympatico.ca> wrote in message
news:45A04DC2.B475BFB1@sympatico.ca...
> Or it's electronic plug and socket are dirty.....
>
> Mike
>
> Jeff Strickland wrote:
>>
>> So, one of the coils is bad.
>>
>> "Carl" <carlsaiyed@hotmailREMOVE.com> wrote in message
>> news:bdqdnb4NANz57QHYnZ2dnUVZ_tOmnZ2d@comcast.com. ..
>> > Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three
>> > coil
>> > packs.
>> >
>> > Carl
>> >
>> >
>> > "Jeff Strickland" <crwlr@yahoo.com> wrote in message
>> > news:OfidnY5u3NmnmQHYnZ2dnUVZ_h6jnZ2d@ez2.net...
>> >> With a misfire, I'd be looking at the plug wires or coil. I'd check
>> >> plug
>> >> wires if there was a distributor, or I'd look at the coil if there was
>> >> a
>> >> separate coil for each cylinder, or a coil for every two cylinders.
>> >>
>> >>
>> >>
>> >> "01XJ" <adam.tsacoumangos@gmail.com> wrote in message
>> >> news:1167779855.090317.153570@v33g2000cwv.googlegr oups.com...
>> >>>I just started experiencing a rough idle on my 2001 Cherokee (78k
>> >>> miles). My engine light went on a little after that with the P0303
>> >>> code. I just replaced the spark plugs, but that didn't help
>> >>> anything.
>> >>> I was
>> >>> thinking about changing the ignition coil or fuel injector. One
>> >>> other
>> >>> possibility I was
>> >>> thinking was checking the cylinder compression (maybe a gasket
>> >>> leak?).
>> >>> Anyone have any suggestions?
>> >>>
>> >>
>> >
>> >

 

There is only one plug, at the rear of coil rail. Three coil packs are on
the rail.

Carl


"Mike Romain" <romainm@sympatico.ca> wrote in message
news:45A04DC2.B475BFB1@sympatico.ca...
> Or it's electronic plug and socket are dirty.....
>
> Mike
>
> Jeff Strickland wrote:
>>
>> So, one of the coils is bad.
>>
>> "Carl" <carlsaiyed@hotmailREMOVE.com> wrote in message
>> news:bdqdnb4NANz57QHYnZ2dnUVZ_tOmnZ2d@comcast.com. ..
>> > Jeff, no plug wires or dist cap on an 00 and 01. Coil rail with three
>> > coil
>> > packs.
>> >
>> > Carl
>> >
>> >
>> > "Jeff Strickland" <crwlr@yahoo.com> wrote in message
>> > news:OfidnY5u3NmnmQHYnZ2dnUVZ_h6jnZ2d@ez2.net...
>> >> With a misfire, I'd be looking at the plug wires or coil. I'd check
>> >> plug
>> >> wires if there was a distributor, or I'd look at the coil if there was
>> >> a
>> >> separate coil for each cylinder, or a coil for every two cylinders.
>> >>
>> >>
>> >>
>> >> "01XJ" <adam.tsacoumangos@gmail.com> wrote in message
>> >> news:1167779855.090317.153570@v33g2000cwv.googlegr oups.com...
>> >>>I just started experiencing a rough idle on my 2001 Cherokee (78k
>> >>> miles). My engine light went on a little after that with the P0303
>> >>> code. I just replaced the spark plugs, but that didn't help
>> >>> anything.
>> >>> I was
>> >>> thinking about changing the ignition coil or fuel injector. One
>> >>> other
>> >>> possibility I was
>> >>> thinking was checking the cylinder compression (maybe a gasket
>> >>> leak?).
>> >>> Anyone have any suggestions?
>> >>>
>> >>
>> >
>> >