Firebird

I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
the code being displayed is P0301, which is misfire in cylinder 1. I finally
brought it to the Jeep dealer, they could not find any issues with the
plugs, wires etc..
So, they reprogrammed the computer, and told me if the lite comes on again
then the cylinder head would require removal and possible replacement would
be required...

The car runs fine...except for the dumb light. DOes anyone experience this
same issue also.
Thanks

Mike Romain

I think I would be first looking at the distributor cap under a strong
light for a small white spider web looking mark around the post for that
cylinder.

I next would take an ohm meter and check the plug wire. I would compare
it to the ohms for #2 or #6 depending on the engine. I believe one of
those wires are the same length as #1, so they should read the 'same'.
It is measured in "X" ohms per foot, so a 2' wire measures double the
"X" of a 1' wire.

I next would spend 2 or 3 bucks and change the damn spark plug, then
pull the battery cables to reset the computer. When I did that, I would
pull another plug to see if #1 looks fouled or really clean in
comparison. (electric misfire vs coolant/compression leak)

'Then' if all else failed I would get a ten dollar compression tester
and check the compression to compare all to #1.

Then I might change the head gasket....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Firebird wrote:
>
> I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
> the code being displayed is P0301, which is misfire in cylinder 1. I finally
> brought it to the Jeep dealer, they could not find any issues with the
> plugs, wires etc..
> So, they reprogrammed the computer, and told me if the lite comes on again
> then the cylinder head would require removal and possible replacement would
> be required...
>
> The car runs fine...except for the dumb light. DOes anyone experience this
> same issue also.
> Thanks

Mike Romain

I think I would be first looking at the distributor cap under a strong
light for a small white spider web looking mark around the post for that
cylinder.

I next would take an ohm meter and check the plug wire. I would compare
it to the ohms for #2 or #6 depending on the engine. I believe one of
those wires are the same length as #1, so they should read the 'same'.
It is measured in "X" ohms per foot, so a 2' wire measures double the
"X" of a 1' wire.

I next would spend 2 or 3 bucks and change the damn spark plug, then
pull the battery cables to reset the computer. When I did that, I would
pull another plug to see if #1 looks fouled or really clean in
comparison. (electric misfire vs coolant/compression leak)

'Then' if all else failed I would get a ten dollar compression tester
and check the compression to compare all to #1.

Then I might change the head gasket....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Firebird wrote:
>
> I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
> the code being displayed is P0301, which is misfire in cylinder 1. I finally
> brought it to the Jeep dealer, they could not find any issues with the
> plugs, wires etc..
> So, they reprogrammed the computer, and told me if the lite comes on again
> then the cylinder head would require removal and possible replacement would
> be required...
>
> The car runs fine...except for the dumb light. DOes anyone experience this
> same issue also.
> Thanks

Mike Romain

I think I would be first looking at the distributor cap under a strong
light for a small white spider web looking mark around the post for that
cylinder.

I next would take an ohm meter and check the plug wire. I would compare
it to the ohms for #2 or #6 depending on the engine. I believe one of
those wires are the same length as #1, so they should read the 'same'.
It is measured in "X" ohms per foot, so a 2' wire measures double the
"X" of a 1' wire.

I next would spend 2 or 3 bucks and change the damn spark plug, then
pull the battery cables to reset the computer. When I did that, I would
pull another plug to see if #1 looks fouled or really clean in
comparison. (electric misfire vs coolant/compression leak)

'Then' if all else failed I would get a ten dollar compression tester
and check the compression to compare all to #1.

Then I might change the head gasket....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Firebird wrote:
>
> I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
> the code being displayed is P0301, which is misfire in cylinder 1. I finally
> brought it to the Jeep dealer, they could not find any issues with the
> plugs, wires etc..
> So, they reprogrammed the computer, and told me if the lite comes on again
> then the cylinder head would require removal and possible replacement would
> be required...
>
> The car runs fine...except for the dumb light. DOes anyone experience this
> same issue also.
> Thanks

Coasty

I would change dealers anyone who said that is about as much of a mechanic
as a rock, it takes a lot more than a misfire code to determine you need a
new head.
Coasty

"Firebird" <erodman@nyc.rr.com> wrote in message
news:1mU1g.24184$nA3.1460@news-wrt-01.rdc-nyc.rr.com...
>I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
>the code being displayed is P0301, which is misfire in cylinder 1. I
>finally brought it to the Jeep dealer, they could not find any issues with
>the plugs, wires etc..
> So, they reprogrammed the computer, and told me if the lite comes on again
> then the cylinder head would require removal and possible replacement
> would be required...
>
> The car runs fine...except for the dumb light. DOes anyone experience
> this same issue also.
> Thanks
>

Coasty

I would change dealers anyone who said that is about as much of a mechanic
as a rock, it takes a lot more than a misfire code to determine you need a
new head.
Coasty

"Firebird" <erodman@nyc.rr.com> wrote in message
news:1mU1g.24184$nA3.1460@news-wrt-01.rdc-nyc.rr.com...
>I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
>the code being displayed is P0301, which is misfire in cylinder 1. I
>finally brought it to the Jeep dealer, they could not find any issues with
>the plugs, wires etc..
> So, they reprogrammed the computer, and told me if the lite comes on again
> then the cylinder head would require removal and possible replacement
> would be required...
>
> The car runs fine...except for the dumb light. DOes anyone experience
> this same issue also.
> Thanks
>

Coasty

I would change dealers anyone who said that is about as much of a mechanic
as a rock, it takes a lot more than a misfire code to determine you need a
new head.
Coasty

"Firebird" <erodman@nyc.rr.com> wrote in message
news:1mU1g.24184$nA3.1460@news-wrt-01.rdc-nyc.rr.com...
>I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
>the code being displayed is P0301, which is misfire in cylinder 1. I
>finally brought it to the Jeep dealer, they could not find any issues with
>the plugs, wires etc..
> So, they reprogrammed the computer, and told me if the lite comes on again
> then the cylinder head would require removal and possible replacement
> would be required...
>
> The car runs fine...except for the dumb light. DOes anyone experience
> this same issue also.
> Thanks
>

DougW

Mike Romain did pass the time by typing:
> I think I would be first looking at the distributor cap under a strong
> light for a small white spider web looking mark around the post for that
> cylinder.

<snippies>

Also if that's a coil on plug setup, 1 and 3 fire at the same time.
A leaky injector on #1 (or a fowled plug) can cause a misfire.

I'd take a look at the plug first.

> Firebird wrote:
>>
>> I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
>> the code being displayed is P0301, which is misfire in cylinder 1. I finally
>> brought it to the Jeep dealer, they could not find any issues with the
>> plugs, wires etc..

--
DougW

DougW

Mike Romain did pass the time by typing:
> I think I would be first looking at the distributor cap under a strong
> light for a small white spider web looking mark around the post for that
> cylinder.

<snippies>

Also if that's a coil on plug setup, 1 and 3 fire at the same time.
A leaky injector on #1 (or a fowled plug) can cause a misfire.

I'd take a look at the plug first.

> Firebird wrote:
>>
>> I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
>> the code being displayed is P0301, which is misfire in cylinder 1. I finally
>> brought it to the Jeep dealer, they could not find any issues with the
>> plugs, wires etc..

--
DougW

DougW

Mike Romain did pass the time by typing:
> I think I would be first looking at the distributor cap under a strong
> light for a small white spider web looking mark around the post for that
> cylinder.

<snippies>

Also if that's a coil on plug setup, 1 and 3 fire at the same time.
A leaky injector on #1 (or a fowled plug) can cause a misfire.

I'd take a look at the plug first.

> Firebird wrote:
>>
>> I have a 2001 Jeep Grand Cherokee Laredo. My check engine light was on and
>> the code being displayed is P0301, which is misfire in cylinder 1. I finally
>> brought it to the Jeep dealer, they could not find any issues with the
>> plugs, wires etc..

--
DougW