4.0 light miss
 

Gang,

My good old 96 Cherokee has a slight miss, and has had it since the new
engine was put in.

Driving down the road at a steady speed or under hard acceleration it's
unnoticeable, it's most noticeable under light to moderate acceleration.

When the new engine was put in it got new plugs, wires, filters,
distributor cap, rotor and front 02 sensor.

I assumed the miss was due to the 7+ month old gas in the tank, so I
started using Techron fuel system cleaner.

10,000 miles and a gallon or so of cleaner later the problem is still
there. Sometimes it almost goes away with the cleaner in it but not
entirely. Then something interesting happened last week.

I put the new downstream O2 sensor in, and of course had the battery
disconnected so the computer would reset. When driving it later much to
my surprise for the first 20 min or the engine ran absolutely
beautifully, then it stated acting up again.

The O2 sensor operation was successful and the "Check Engine" light is
staying out, but something is off enough to keep the engine from running
quite right.

So it seems as though when it's in learning mode (using default
settings?) it works great, but as it picks up the information from the
Jeeps sensors it gets out of whack.

Have I got a sensor going (gone) bad but not quite enough to trigger the
light or..?

Any suggestions?

Thanks!

Jeff DeWitt

Re: 4.0 light miss
 

Jeffrey DeWitt wrote:
> Gang,
>
> My good old 96 Cherokee has a slight miss, and has had it since the
> new engine was put in.

I had a slight miss on my 93 4.0 for quite a while and it turned out
to be the coil assembly. Coil and resistance wire were a recall for
several years and if you don't have the correct one it seems to throw
the timing off. Dunno exacly how, but it did solve my problem.
http://partimages2.genpt.com/partimages/103447.jpg

The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
and prior to this I had to run 93 or suffer highway ping.

And also the fuel filter, but usually that is ping only at full throttle.

--
DougW

Re: 4.0 light miss
 

Jeffrey DeWitt wrote:
> Gang,
>
> My good old 96 Cherokee has a slight miss, and has had it since the
> new engine was put in.

I had a slight miss on my 93 4.0 for quite a while and it turned out
to be the coil assembly. Coil and resistance wire were a recall for
several years and if you don't have the correct one it seems to throw
the timing off. Dunno exacly how, but it did solve my problem.
http://partimages2.genpt.com/partimages/103447.jpg

The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
and prior to this I had to run 93 or suffer highway ping.

And also the fuel filter, but usually that is ping only at full throttle.

--
DougW

Re: 4.0 light miss
 

Jeffrey DeWitt wrote:
> Gang,
>
> My good old 96 Cherokee has a slight miss, and has had it since the
> new engine was put in.

I had a slight miss on my 93 4.0 for quite a while and it turned out
to be the coil assembly. Coil and resistance wire were a recall for
several years and if you don't have the correct one it seems to throw
the timing off. Dunno exacly how, but it did solve my problem.
http://partimages2.genpt.com/partimages/103447.jpg

The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
and prior to this I had to run 93 or suffer highway ping.

And also the fuel filter, but usually that is ping only at full throttle.

--
DougW

Re: 4.0 light miss
 

DougW wrote:
> Jeffrey DeWitt wrote:
> > Gang,
> >
> > My good old 96 Cherokee has a slight miss, and has had it since the
> > new engine was put in.
>
> I had a slight miss on my 93 4.0 for quite a while and it turned out
> to be the coil assembly. Coil and resistance wire were a recall for
> several years and if you don't have the correct one it seems to throw
> the timing off. Dunno exacly how, but it did solve my problem.
> http://partimages2.genpt.com/partimages/103447.jpg
>
> The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> and prior to this I had to run 93 or suffer highway ping.
>
> And also the fuel filter, but usually that is ping only at full throttle.
>
> --
> DougW

I've got no problem replacing the coil if that will fix it, but if it
is the coil why will the engine sometimes run better with injector
cleaner in it, and why did it run so well for a few min. while the
computer was resetting?

Jeff DeWitt

Re: 4.0 light miss
 

DougW wrote:
> Jeffrey DeWitt wrote:
> > Gang,
> >
> > My good old 96 Cherokee has a slight miss, and has had it since the
> > new engine was put in.
>
> I had a slight miss on my 93 4.0 for quite a while and it turned out
> to be the coil assembly. Coil and resistance wire were a recall for
> several years and if you don't have the correct one it seems to throw
> the timing off. Dunno exacly how, but it did solve my problem.
> http://partimages2.genpt.com/partimages/103447.jpg
>
> The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> and prior to this I had to run 93 or suffer highway ping.
>
> And also the fuel filter, but usually that is ping only at full throttle.
>
> --
> DougW

I've got no problem replacing the coil if that will fix it, but if it
is the coil why will the engine sometimes run better with injector
cleaner in it, and why did it run so well for a few min. while the
computer was resetting?

Jeff DeWitt

Re: 4.0 light miss
 

DougW wrote:
> Jeffrey DeWitt wrote:
> > Gang,
> >
> > My good old 96 Cherokee has a slight miss, and has had it since the
> > new engine was put in.
>
> I had a slight miss on my 93 4.0 for quite a while and it turned out
> to be the coil assembly. Coil and resistance wire were a recall for
> several years and if you don't have the correct one it seems to throw
> the timing off. Dunno exacly how, but it did solve my problem.
> http://partimages2.genpt.com/partimages/103447.jpg
>
> The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> and prior to this I had to run 93 or suffer highway ping.
>
> And also the fuel filter, but usually that is ping only at full throttle.
>
> --
> DougW

I've got no problem replacing the coil if that will fix it, but if it
is the coil why will the engine sometimes run better with injector
cleaner in it, and why did it run so well for a few min. while the
computer was resetting?

Jeff DeWitt

Re: 4.0 light miss
 

JeffDeWitt wrote:
> DougW wrote:
>> Jeffrey DeWitt wrote:

>>> My good old 96 Cherokee has a slight miss, and has had it since the
>>> new engine was put in.
>>
>> I had a slight miss on my 93 4.0 for quite a while and it turned out
>> to be the coil assembly. Coil and resistance wire were a recall for
>> several years and if you don't have the correct one it seems to throw
>> the timing off. Dunno exacly how, but it did solve my problem.
>> http://partimages2.genpt.com/partimages/103447.jpg
>>
>> The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a
>> blower and prior to this I had to run 93 or suffer highway ping.
>>
>> And also the fuel filter, but usually that is ping only at full
>> throttle.

> I've got no problem replacing the coil if that will fix it, but if it
> is the coil why will the engine sometimes run better with injector
> cleaner in it, and why did it run so well for a few min. while the
> computer was resetting?

That was my thought as well. Close as I can tell, the new coil has
a longer connecting wire and uses a resistance balast, that might
account for a "tiny" bit more delay.

Adding injector cleaner, like running high octane fuel or running
in startup where the engine is made rich, are all the same things.
The computer only adjusts timing so much, it assumes the rest of
the system is working properly.

All I can say is that doing that got rid of my pinging. Worst off
you have a spare coil.

--
DougW

Re: 4.0 light miss
 

JeffDeWitt wrote:
> DougW wrote:
>> Jeffrey DeWitt wrote:

>>> My good old 96 Cherokee has a slight miss, and has had it since the
>>> new engine was put in.
>>
>> I had a slight miss on my 93 4.0 for quite a while and it turned out
>> to be the coil assembly. Coil and resistance wire were a recall for
>> several years and if you don't have the correct one it seems to throw
>> the timing off. Dunno exacly how, but it did solve my problem.
>> http://partimages2.genpt.com/partimages/103447.jpg
>>
>> The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a
>> blower and prior to this I had to run 93 or suffer highway ping.
>>
>> And also the fuel filter, but usually that is ping only at full
>> throttle.

> I've got no problem replacing the coil if that will fix it, but if it
> is the coil why will the engine sometimes run better with injector
> cleaner in it, and why did it run so well for a few min. while the
> computer was resetting?

That was my thought as well. Close as I can tell, the new coil has
a longer connecting wire and uses a resistance balast, that might
account for a "tiny" bit more delay.

Adding injector cleaner, like running high octane fuel or running
in startup where the engine is made rich, are all the same things.
The computer only adjusts timing so much, it assumes the rest of
the system is working properly.

All I can say is that doing that got rid of my pinging. Worst off
you have a spare coil.

--
DougW

Re: 4.0 light miss
 

JeffDeWitt wrote:
> DougW wrote:
>> Jeffrey DeWitt wrote:

>>> My good old 96 Cherokee has a slight miss, and has had it since the
>>> new engine was put in.
>>
>> I had a slight miss on my 93 4.0 for quite a while and it turned out
>> to be the coil assembly. Coil and resistance wire were a recall for
>> several years and if you don't have the correct one it seems to throw
>> the timing off. Dunno exacly how, but it did solve my problem.
>> http://partimages2.genpt.com/partimages/103447.jpg
>>
>> The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a
>> blower and prior to this I had to run 93 or suffer highway ping.
>>
>> And also the fuel filter, but usually that is ping only at full
>> throttle.

> I've got no problem replacing the coil if that will fix it, but if it
> is the coil why will the engine sometimes run better with injector
> cleaner in it, and why did it run so well for a few min. while the
> computer was resetting?

That was my thought as well. Close as I can tell, the new coil has
a longer connecting wire and uses a resistance balast, that might
account for a "tiny" bit more delay.

Adding injector cleaner, like running high octane fuel or running
in startup where the engine is made rich, are all the same things.
The computer only adjusts timing so much, it assumes the rest of
the system is working properly.

All I can say is that doing that got rid of my pinging. Worst off
you have a spare coil.

--
DougW

Re: 4.0 light miss
 

On Fri, 6 Oct 2006 17:07:57 UTC "JeffDeWitt" <jeffdewitt@gmail.com>
wrote:

>
> DougW wrote:
> > Jeffrey DeWitt wrote:
> > > Gang,
> > >
> > > My good old 96 Cherokee has a slight miss, and has had it since the
> > > new engine was put in.
> >
> > I had a slight miss on my 93 4.0 for quite a while and it turned out
> > to be the coil assembly. Coil and resistance wire were a recall for
> > several years and if you don't have the correct one it seems to throw
> > the timing off. Dunno exacly how, but it did solve my problem.
> > http://partimages2.genpt.com/partimages/103447.jpg
> >
> > The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> > and prior to this I had to run 93 or suffer highway ping.
> >
> > And also the fuel filter, but usually that is ping only at full throttle.
> >
> > --
> > DougW
>
> I've got no problem replacing the coil if that will fix it, but if it
> is the coil why will the engine sometimes run better with injector
> cleaner in it, and why did it run so well for a few min. while the
> computer was resetting?

You might want to check the fuel pressure on the rail as well -
marginal pressure or low pump capacity can cause what you see as well.

--
Will Honea

Re: 4.0 light miss
 

On Fri, 6 Oct 2006 17:07:57 UTC "JeffDeWitt" <jeffdewitt@gmail.com>
wrote:

>
> DougW wrote:
> > Jeffrey DeWitt wrote:
> > > Gang,
> > >
> > > My good old 96 Cherokee has a slight miss, and has had it since the
> > > new engine was put in.
> >
> > I had a slight miss on my 93 4.0 for quite a while and it turned out
> > to be the coil assembly. Coil and resistance wire were a recall for
> > several years and if you don't have the correct one it seems to throw
> > the timing off. Dunno exacly how, but it did solve my problem.
> > http://partimages2.genpt.com/partimages/103447.jpg
> >
> > The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> > and prior to this I had to run 93 or suffer highway ping.
> >
> > And also the fuel filter, but usually that is ping only at full throttle.
> >
> > --
> > DougW
>
> I've got no problem replacing the coil if that will fix it, but if it
> is the coil why will the engine sometimes run better with injector
> cleaner in it, and why did it run so well for a few min. while the
> computer was resetting?

You might want to check the fuel pressure on the rail as well -
marginal pressure or low pump capacity can cause what you see as well.

--
Will Honea

Re: 4.0 light miss
 

On Fri, 6 Oct 2006 17:07:57 UTC "JeffDeWitt" <jeffdewitt@gmail.com>
wrote:

>
> DougW wrote:
> > Jeffrey DeWitt wrote:
> > > Gang,
> > >
> > > My good old 96 Cherokee has a slight miss, and has had it since the
> > > new engine was put in.
> >
> > I had a slight miss on my 93 4.0 for quite a while and it turned out
> > to be the coil assembly. Coil and resistance wire were a recall for
> > several years and if you don't have the correct one it seems to throw
> > the timing off. Dunno exacly how, but it did solve my problem.
> > http://partimages2.genpt.com/partimages/103447.jpg
> >
> > The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> > and prior to this I had to run 93 or suffer highway ping.
> >
> > And also the fuel filter, but usually that is ping only at full throttle.
> >
> > --
> > DougW
>
> I've got no problem replacing the coil if that will fix it, but if it
> is the coil why will the engine sometimes run better with injector
> cleaner in it, and why did it run so well for a few min. while the
> computer was resetting?

You might want to check the fuel pressure on the rail as well -
marginal pressure or low pump capacity can cause what you see as well.

--
Will Honea

Re: 4.0 light miss
 

I might go ahead and put a new coil on anyway, it's easy and it IS the
orginal coil so it shouldn't hurt to put in a new one, and as Doug
points out it's not bad to have a spare.

I've also wondered about that fuel pump, it's orginal too, looks like a
new pump is about $100 and a gage to check the old one is about $35 so
maybe it would be a good idea to just replace the pump but I can't say
I'm thrilled about the idea... somehow I expect that pump is a LOT
harder to replace than the one on my Studebaker truck (two fittings,
two bolts, 15 min.).

Jeff DeWitt
Will Honea wrote:
> On Fri, 6 Oct 2006 17:07:57 UTC "JeffDeWitt" <jeffdewitt@gmail.com>
> wrote:
>
> >
> > DougW wrote:
> > > Jeffrey DeWitt wrote:
> > > > Gang,
> > > >
> > > > My good old 96 Cherokee has a slight miss, and has had it since the
> > > > new engine was put in.
> > >
> > > I had a slight miss on my 93 4.0 for quite a while and it turned out
> > > to be the coil assembly. Coil and resistance wire were a recall for
> > > several years and if you don't have the correct one it seems to throw
> > > the timing off. Dunno exacly how, but it did solve my problem.
> > > http://partimages2.genpt.com/partimages/103447.jpg
> > >
> > > The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> > > and prior to this I had to run 93 or suffer highway ping.
> > >
> > > And also the fuel filter, but usually that is ping only at full throttle.
> > >
> > > --
> > > DougW
> >
> > I've got no problem replacing the coil if that will fix it, but if it
> > is the coil why will the engine sometimes run better with injector
> > cleaner in it, and why did it run so well for a few min. while the
> > computer was resetting?
>
> You might want to check the fuel pressure on the rail as well -
> marginal pressure or low pump capacity can cause what you see as well.
>
> --
> Will Honea

Re: 4.0 light miss
 

I might go ahead and put a new coil on anyway, it's easy and it IS the
orginal coil so it shouldn't hurt to put in a new one, and as Doug
points out it's not bad to have a spare.

I've also wondered about that fuel pump, it's orginal too, looks like a
new pump is about $100 and a gage to check the old one is about $35 so
maybe it would be a good idea to just replace the pump but I can't say
I'm thrilled about the idea... somehow I expect that pump is a LOT
harder to replace than the one on my Studebaker truck (two fittings,
two bolts, 15 min.).

Jeff DeWitt
Will Honea wrote:
> On Fri, 6 Oct 2006 17:07:57 UTC "JeffDeWitt" <jeffdewitt@gmail.com>
> wrote:
>
> >
> > DougW wrote:
> > > Jeffrey DeWitt wrote:
> > > > Gang,
> > > >
> > > > My good old 96 Cherokee has a slight miss, and has had it since the
> > > > new engine was put in.
> > >
> > > I had a slight miss on my 93 4.0 for quite a while and it turned out
> > > to be the coil assembly. Coil and resistance wire were a recall for
> > > several years and if you don't have the correct one it seems to throw
> > > the timing off. Dunno exacly how, but it did solve my problem.
> > > http://partimages2.genpt.com/partimages/103447.jpg
> > >
> > > The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> > > and prior to this I had to run 93 or suffer highway ping.
> > >
> > > And also the fuel filter, but usually that is ping only at full throttle.
> > >
> > > --
> > > DougW
> >
> > I've got no problem replacing the coil if that will fix it, but if it
> > is the coil why will the engine sometimes run better with injector
> > cleaner in it, and why did it run so well for a few min. while the
> > computer was resetting?
>
> You might want to check the fuel pressure on the rail as well -
> marginal pressure or low pump capacity can cause what you see as well.
>
> --
> Will Honea

Re: 4.0 light miss
 

I might go ahead and put a new coil on anyway, it's easy and it IS the
orginal coil so it shouldn't hurt to put in a new one, and as Doug
points out it's not bad to have a spare.

I've also wondered about that fuel pump, it's orginal too, looks like a
new pump is about $100 and a gage to check the old one is about $35 so
maybe it would be a good idea to just replace the pump but I can't say
I'm thrilled about the idea... somehow I expect that pump is a LOT
harder to replace than the one on my Studebaker truck (two fittings,
two bolts, 15 min.).

Jeff DeWitt
Will Honea wrote:
> On Fri, 6 Oct 2006 17:07:57 UTC "JeffDeWitt" <jeffdewitt@gmail.com>
> wrote:
>
> >
> > DougW wrote:
> > > Jeffrey DeWitt wrote:
> > > > Gang,
> > > >
> > > > My good old 96 Cherokee has a slight miss, and has had it since the
> > > > new engine was put in.
> > >
> > > I had a slight miss on my 93 4.0 for quite a while and it turned out
> > > to be the coil assembly. Coil and resistance wire were a recall for
> > > several years and if you don't have the correct one it seems to throw
> > > the timing off. Dunno exacly how, but it did solve my problem.
> > > http://partimages2.genpt.com/partimages/103447.jpg
> > >
> > > The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> > > and prior to this I had to run 93 or suffer highway ping.
> > >
> > > And also the fuel filter, but usually that is ping only at full throttle.
> > >
> > > --
> > > DougW
> >
> > I've got no problem replacing the coil if that will fix it, but if it
> > is the coil why will the engine sometimes run better with injector
> > cleaner in it, and why did it run so well for a few min. while the
> > computer was resetting?
>
> You might want to check the fuel pressure on the rail as well -
> marginal pressure or low pump capacity can cause what you see as well.
>
> --
> Will Honea

Re: 4.0 light miss
 

I might go ahead and put a new coil on anyway, it's easy and it IS the
orginal coil so it shouldn't hurt to put in a new one, and as Doug
points out it's not bad to have a spare.

I've also wondered about that fuel pump, it's orginal too, looks like a
new pump is about $100 and a gage to check the old one is about $35 so
maybe it would be a good idea to just replace the pump but I can't say
I'm thrilled about the idea... somehow I expect that pump is a LOT
harder to replace than the one on my Studebaker truck (two fittings,
two bolts, 15 min.).

Jeff DeWitt
Will Honea wrote:
> On Fri, 6 Oct 2006 17:07:57 UTC "JeffDeWitt" <jeffdewitt@gmail.com>
> wrote:
>
> >
> > DougW wrote:
> > > Jeffrey DeWitt wrote:
> > > > Gang,
> > > >
> > > > My good old 96 Cherokee has a slight miss, and has had it since the
> > > > new engine was put in.
> > >
> > > I had a slight miss on my 93 4.0 for quite a while and it turned out
> > > to be the coil assembly. Coil and resistance wire were a recall for
> > > several years and if you don't have the correct one it seems to throw
> > > the timing off. Dunno exacly how, but it did solve my problem.
> > > http://partimages2.genpt.com/partimages/103447.jpg
> > >
> > > The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> > > and prior to this I had to run 93 or suffer highway ping.
> > >
> > > And also the fuel filter, but usually that is ping only at full throttle.
> > >
> > > --
> > > DougW
> >
> > I've got no problem replacing the coil if that will fix it, but if it
> > is the coil why will the engine sometimes run better with injector
> > cleaner in it, and why did it run so well for a few min. while the
> > computer was resetting?
>
> You might want to check the fuel pressure on the rail as well -
> marginal pressure or low pump capacity can cause what you see as well.
>
> --
> Will Honea

Re: 4.0 light miss
 

I might go ahead and put a new coil on anyway, it's easy and it IS the
orginal coil so it shouldn't hurt to put in a new one, and as Doug
points out it's not bad to have a spare.

I've also wondered about that fuel pump, it's orginal too, looks like a
new pump is about $100 and a gage to check the old one is about $35 so
maybe it would be a good idea to just replace the pump but I can't say
I'm thrilled about the idea... somehow I expect that pump is a LOT
harder to replace than the one on my Studebaker truck (two fittings,
two bolts, 15 min.).

Jeff DeWitt
Will Honea wrote:
> On Fri, 6 Oct 2006 17:07:57 UTC "JeffDeWitt" <jeffdewitt@gmail.com>
> wrote:
>
> >
> > DougW wrote:
> > > Jeffrey DeWitt wrote:
> > > > Gang,
> > > >
> > > > My good old 96 Cherokee has a slight miss, and has had it since the
> > > > new engine was put in.
> > >
> > > I had a slight miss on my 93 4.0 for quite a while and it turned out
> > > to be the coil assembly. Coil and resistance wire were a recall for
> > > several years and if you don't have the correct one it seems to throw
> > > the timing off. Dunno exacly how, but it did solve my problem.
> > > http://partimages2.genpt.com/partimages/103447.jpg
> > >
> > > The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> > > and prior to this I had to run 93 or suffer highway ping.
> > >
> > > And also the fuel filter, but usually that is ping only at full throttle.
> > >
> > > --
> > > DougW
> >
> > I've got no problem replacing the coil if that will fix it, but if it
> > is the coil why will the engine sometimes run better with injector
> > cleaner in it, and why did it run so well for a few min. while the
> > computer was resetting?
>
> You might want to check the fuel pressure on the rail as well -
> marginal pressure or low pump capacity can cause what you see as well.
>
> --
> Will Honea

Re: 4.0 light miss
 

I might go ahead and put a new coil on anyway, it's easy and it IS the
orginal coil so it shouldn't hurt to put in a new one, and as Doug
points out it's not bad to have a spare.

I've also wondered about that fuel pump, it's orginal too, looks like a
new pump is about $100 and a gage to check the old one is about $35 so
maybe it would be a good idea to just replace the pump but I can't say
I'm thrilled about the idea... somehow I expect that pump is a LOT
harder to replace than the one on my Studebaker truck (two fittings,
two bolts, 15 min.).

Jeff DeWitt
Will Honea wrote:
> On Fri, 6 Oct 2006 17:07:57 UTC "JeffDeWitt" <jeffdewitt@gmail.com>
> wrote:
>
> >
> > DougW wrote:
> > > Jeffrey DeWitt wrote:
> > > > Gang,
> > > >
> > > > My good old 96 Cherokee has a slight miss, and has had it since the
> > > > new engine was put in.
> > >
> > > I had a slight miss on my 93 4.0 for quite a while and it turned out
> > > to be the coil assembly. Coil and resistance wire were a recall for
> > > several years and if you don't have the correct one it seems to throw
> > > the timing off. Dunno exacly how, but it did solve my problem.
> > > http://partimages2.genpt.com/partimages/103447.jpg
> > >
> > > The ZJ can now run 91 with no problem.. keep in mind my 4.0 has a blower
> > > and prior to this I had to run 93 or suffer highway ping.
> > >
> > > And also the fuel filter, but usually that is ping only at full throttle.
> > >
> > > --
> > > DougW
> >
> > I've got no problem replacing the coil if that will fix it, but if it
> > is the coil why will the engine sometimes run better with injector
> > cleaner in it, and why did it run so well for a few min. while the
> > computer was resetting?
>
> You might want to check the fuel pressure on the rail as well -
> marginal pressure or low pump capacity can cause what you see as well.
>
> --
> Will Honea

Re: 4.0 light miss
 

JeffDeWitt wrote:
> I might go ahead and put a new coil on anyway, it's easy and it IS the
> orginal coil so it shouldn't hurt to put in a new one, and as Doug
> points out it's not bad to have a spare.

Double check the part but I used the NAPA part ECHIC409. It's the
same one that was used for a recall Jeep had a long time back. Comes
with a coil and adapter harness. You have to use the harness with this
coil as it contains a balast resistor.

Other than that it depends on if you have blades or pins. My factory
connector is pins, the later model is blade.

> I've also wondered about that fuel pump, it's orginal too, looks like
> a new pump is about $100 and a gage to check the old one is about $35
> so maybe it would be a good idea to just replace the pump but I can't
> say I'm thrilled about the idea... somehow I expect that pump is a LOT
> harder to replace than the one on my Studebaker truck (two fittings,
> two bolts, 15 min.).

Fuel pump pressure is easy to check if you have an old R-12 gauge
or stop by autozone (or sears) and buy one. Just hook it up and
duct tape it to the windshield.

My pump still works. Generally if the filter is clogged or the pump is
shot, you will get real bad ping under load and at wide-open-throttle.
Both times I've gotten ping at WOT it's been due to a clogged filter.
http://revbeergoggles.com/badgas/


--
DougW

Re: 4.0 light miss
 

JeffDeWitt wrote:
> I might go ahead and put a new coil on anyway, it's easy and it IS the
> orginal coil so it shouldn't hurt to put in a new one, and as Doug
> points out it's not bad to have a spare.

Double check the part but I used the NAPA part ECHIC409. It's the
same one that was used for a recall Jeep had a long time back. Comes
with a coil and adapter harness. You have to use the harness with this
coil as it contains a balast resistor.

Other than that it depends on if you have blades or pins. My factory
connector is pins, the later model is blade.

> I've also wondered about that fuel pump, it's orginal too, looks like
> a new pump is about $100 and a gage to check the old one is about $35
> so maybe it would be a good idea to just replace the pump but I can't
> say I'm thrilled about the idea... somehow I expect that pump is a LOT
> harder to replace than the one on my Studebaker truck (two fittings,
> two bolts, 15 min.).

Fuel pump pressure is easy to check if you have an old R-12 gauge
or stop by autozone (or sears) and buy one. Just hook it up and
duct tape it to the windshield.

My pump still works. Generally if the filter is clogged or the pump is
shot, you will get real bad ping under load and at wide-open-throttle.
Both times I've gotten ping at WOT it's been due to a clogged filter.
http://revbeergoggles.com/badgas/


--
DougW

Re: 4.0 light miss
 

JeffDeWitt wrote:
> I might go ahead and put a new coil on anyway, it's easy and it IS the
> orginal coil so it shouldn't hurt to put in a new one, and as Doug
> points out it's not bad to have a spare.

Double check the part but I used the NAPA part ECHIC409. It's the
same one that was used for a recall Jeep had a long time back. Comes
with a coil and adapter harness. You have to use the harness with this
coil as it contains a balast resistor.

Other than that it depends on if you have blades or pins. My factory
connector is pins, the later model is blade.

> I've also wondered about that fuel pump, it's orginal too, looks like
> a new pump is about $100 and a gage to check the old one is about $35
> so maybe it would be a good idea to just replace the pump but I can't
> say I'm thrilled about the idea... somehow I expect that pump is a LOT
> harder to replace than the one on my Studebaker truck (two fittings,
> two bolts, 15 min.).

Fuel pump pressure is easy to check if you have an old R-12 gauge
or stop by autozone (or sears) and buy one. Just hook it up and
duct tape it to the windshield.

My pump still works. Generally if the filter is clogged or the pump is
shot, you will get real bad ping under load and at wide-open-throttle.
Both times I've gotten ping at WOT it's been due to a clogged filter.
http://revbeergoggles.com/badgas/


--
DougW

Re: 4.0 light miss
 

Hmm, picked up a new coil on the way home from work yesterday, nothing
in the box but the coil, and it was a Borg-Warner brand coil.

Since when did Borg-Warner start making ignition parts?

I believe mine has the blade pins.

Jeff DeWitt

DougW wrote:
> JeffDeWitt wrote:
> > I might go ahead and put a new coil on anyway, it's easy and it IS the
> > orginal coil so it shouldn't hurt to put in a new one, and as Doug
> > points out it's not bad to have a spare.
>
> Double check the part but I used the NAPA part ECHIC409. It's the
> same one that was used for a recall Jeep had a long time back. Comes
> with a coil and adapter harness. You have to use the harness with this
> coil as it contains a balast resistor.
>
> Other than that it depends on if you have blades or pins. My factory
> connector is pins, the later model is blade.
>
> > I've also wondered about that fuel pump, it's orginal too, looks like
> > a new pump is about $100 and a gage to check the old one is about $35
> > so maybe it would be a good idea to just replace the pump but I can't
> > say I'm thrilled about the idea... somehow I expect that pump is a LOT
> > harder to replace than the one on my Studebaker truck (two fittings,
> > two bolts, 15 min.).
>
> Fuel pump pressure is easy to check if you have an old R-12 gauge
> or stop by autozone (or sears) and buy one. Just hook it up and
> duct tape it to the windshield.
>
> My pump still works. Generally if the filter is clogged or the pump is
> shot, you will get real bad ping under load and at wide-open-throttle.
> Both times I've gotten ping at WOT it's been due to a clogged filter.
> http://revbeergoggles.com/badgas/
>
>
> --
> DougW

Re: 4.0 light miss
 

Hmm, picked up a new coil on the way home from work yesterday, nothing
in the box but the coil, and it was a Borg-Warner brand coil.

Since when did Borg-Warner start making ignition parts?

I believe mine has the blade pins.

Jeff DeWitt

DougW wrote:
> JeffDeWitt wrote:
> > I might go ahead and put a new coil on anyway, it's easy and it IS the
> > orginal coil so it shouldn't hurt to put in a new one, and as Doug
> > points out it's not bad to have a spare.
>
> Double check the part but I used the NAPA part ECHIC409. It's the
> same one that was used for a recall Jeep had a long time back. Comes
> with a coil and adapter harness. You have to use the harness with this
> coil as it contains a balast resistor.
>
> Other than that it depends on if you have blades or pins. My factory
> connector is pins, the later model is blade.
>
> > I've also wondered about that fuel pump, it's orginal too, looks like
> > a new pump is about $100 and a gage to check the old one is about $35
> > so maybe it would be a good idea to just replace the pump but I can't
> > say I'm thrilled about the idea... somehow I expect that pump is a LOT
> > harder to replace than the one on my Studebaker truck (two fittings,
> > two bolts, 15 min.).
>
> Fuel pump pressure is easy to check if you have an old R-12 gauge
> or stop by autozone (or sears) and buy one. Just hook it up and
> duct tape it to the windshield.
>
> My pump still works. Generally if the filter is clogged or the pump is
> shot, you will get real bad ping under load and at wide-open-throttle.
> Both times I've gotten ping at WOT it's been due to a clogged filter.
> http://revbeergoggles.com/badgas/
>
>
> --
> DougW

Re: 4.0 light miss
 

Hmm, picked up a new coil on the way home from work yesterday, nothing
in the box but the coil, and it was a Borg-Warner brand coil.

Since when did Borg-Warner start making ignition parts?

I believe mine has the blade pins.

Jeff DeWitt

DougW wrote:
> JeffDeWitt wrote:
> > I might go ahead and put a new coil on anyway, it's easy and it IS the
> > orginal coil so it shouldn't hurt to put in a new one, and as Doug
> > points out it's not bad to have a spare.
>
> Double check the part but I used the NAPA part ECHIC409. It's the
> same one that was used for a recall Jeep had a long time back. Comes
> with a coil and adapter harness. You have to use the harness with this
> coil as it contains a balast resistor.
>
> Other than that it depends on if you have blades or pins. My factory
> connector is pins, the later model is blade.
>
> > I've also wondered about that fuel pump, it's orginal too, looks like
> > a new pump is about $100 and a gage to check the old one is about $35
> > so maybe it would be a good idea to just replace the pump but I can't
> > say I'm thrilled about the idea... somehow I expect that pump is a LOT
> > harder to replace than the one on my Studebaker truck (two fittings,
> > two bolts, 15 min.).
>
> Fuel pump pressure is easy to check if you have an old R-12 gauge
> or stop by autozone (or sears) and buy one. Just hook it up and
> duct tape it to the windshield.
>
> My pump still works. Generally if the filter is clogged or the pump is
> shot, you will get real bad ping under load and at wide-open-throttle.
> Both times I've gotten ping at WOT it's been due to a clogged filter.
> http://revbeergoggles.com/badgas/
>
>
> --
> DougW