2K GT single cylinder misfire mystery

I had an OBDII code check and it told me that cylinder#5 has been
misfiring. Since I never changed the plugs (after 100K miles), I
changed all 8, and the problem went away for a few weeks. Now, the
same cylinder is misfiring again.

What I also noticed is that when the car is in the garage for more
than a week, the misfiring always happens on first (cold) start. If I
use the car the next day, all is OK.

Should I change the coil as well or the wiring harness (which seems
like a huge pain to do)???
Thanks
Mark
2000 GT 'vert

On Jun 11, 9:20*am, "Mark G7#9" > wrote:
> I had an OBDII code check and it told me that cylinder#5 has been
> misfiring. Since I never changed the plugs (after 100K miles), I
> changed all 8, and the problem went away for a few weeks. Now, the
> same cylinder is misfiring again.
>
> What I also noticed is that when the car is in the garage for more
> than a week, the misfiring always happens on first (cold) start. If I
> use the car the next day, all is OK.
>
> Should I change the coil as well or the wiring harness (which seems
> like a huge pain to do)???
> Thanks
> Mark
> 2000 GT 'vert

Exchange the coil pack with another cylinder and reset the PCM. If the
problem moves it's the coil pack. If it stays on hole number 5 there
it's a different problem. You could then do that same swap with the
injector to eliminate/verify an injector problem.

Dan
2003 Cobra Convertible
With Some Stuff and Things

On Jun 11, 5:34*pm, Dan > wrote:
> On Jun 11, 9:20*am, "Mark G7#9" > wrote:
>
> > I had an OBDII code check and it told me that cylinder#5 has been
> > misfiring. Since I never changed the plugs (after 100K miles), I
> > changed all 8, and the problem went away for a few weeks. Now, the
> > same cylinder is misfiring again.
>
> > What I also noticed is that when the car is in the garage for more
> > than a week, the misfiring always happens on first (cold) start. If I
> > use the car the next day, all is OK.
>
> > Should I change the coil as well or the wiring harness (which seems
> > like a huge pain to do)???
> > Thanks
> > Mark
> > 2000 GT 'vert
>
> Exchange the coil pack with another cylinder and reset the PCM. If the
> problem moves it's the coil pack. If it stays on hole number 5 there
> it's a different problem. You could then do that same swap with the
> injector to eliminate/verify an injector problem.
>
> Dan
> 2003 Cobra Convertible
> With Some Stuff and Things

Good advice (should of thought of it myself). Not sure how to swap the
imjector though. Isn't it integrated into the fuel rail thingy?

On Jun 12, 8:18*am, "Mark G7#9" > wrote:
> On Jun 11, 5:34*pm, Dan > wrote:
>
>
>
>
>
> > On Jun 11, 9:20*am, "Mark G7#9" > wrote:
>
> > > I had an OBDII code check and it told me that cylinder#5 has been
> > > misfiring. Since I never changed the plugs (after 100K miles), I
> > > changed all 8, and the problem went away for a few weeks. Now, the
> > > same cylinder is misfiring again.
>
> > > What I also noticed is that when the car is in the garage for more
> > > than a week, the misfiring always happens on first (cold) start. If I
> > > use the car the next day, all is OK.
>
> > > Should I change the coil as well or the wiring harness (which seems
> > > like a huge pain to do)???
> > > Thanks
> > > Mark
> > > 2000 GT 'vert
>
> > Exchange the coil pack with another cylinder and reset the PCM. If the
> > problem moves it's the coil pack. If it stays on hole number 5 there
> > it's a different problem. You could then do that same swap with the
> > injector to eliminate/verify an injector problem.
>
> > Dan
> > 2003 Cobra Convertible
> > With Some Stuff and Things
>
> Good advice (should of thought of it myself). Not sure how to swap the
> imjector though. Isn't it integrated into the fuel rail thingy?- Hide quoted text -
>
> - Show quoted text -

Well, not integrated into as much as attached to . The inlet side of
the injectors are clipped/mounted to the rail and the rail is bolted
down to the manifold. The oulet side just press fits into the manifold
hole with an O-ring for a seal.

Dan
P49Y+

On Jun 12, 11:12*am, Dan > wrote:
> On Jun 12, 8:18*am, "Mark G7#9" > wrote:
>
>
>
>
>
> > On Jun 11, 5:34*pm, Dan > wrote:
>
> > > On Jun 11, 9:20*am, "Mark G7#9" > wrote:
>
> > > > I had an OBDII code check and it told me that cylinder#5 has been
> > > > misfiring. Since I never changed the plugs (after 100K miles), I
> > > > changed all 8, and the problem went away for a few weeks. Now, the
> > > > same cylinder is misfiring again.
>
> > > > What I also noticed is that when the car is in the garage for more
> > > > than a week, the misfiring always happens on first (cold) start. If I
> > > > use the car the next day, all is OK.
>
> > > > Should I change the coil as well or the wiring harness (which seems
> > > > like a huge pain to do)???
> > > > Thanks
> > > > Mark
> > > > 2000 GT 'vert
>
> > > Exchange the coil pack with another cylinder and reset the PCM. If the
> > > problem moves it's the coil pack. If it stays on hole number 5 there
> > > it's a different problem. You could then do that same swap with the
> > > injector to eliminate/verify an injector problem.
>
> > > Dan
> > > 2003 Cobra Convertible
> > > With Some Stuff and Things
>
> > Good advice (should of thought of it myself). Not sure how to swap the
> > imjector though. Isn't it integrated into the fuel rail thingy?- Hide quoted text -
>
> > - Show quoted text -
>
> Well, not integrated into as much as attached to . The inlet side of
> the injectors are clipped/mounted to the rail and the rail is bolted
> down to the manifold. The oulet side just press fits into the manifold
> hole with an O-ring for a seal.
>
> Dan
> P49Y+- Hide quoted text -
>
> - Show quoted text -

I'm thinking that the coil may be eliminated as a problem since it
would be bad all the time , not just on cold starts. The injector may
be affected though since over time of long rests, maybe something goes
funny with the mixture. Makes sense?

"Mark G7#9" > wrote in message
...
On Jun 11, 5:34 pm, Dan > wrote:
> On Jun 11, 9:20 am, "Mark G7#9" > wrote:
>
> > I had an OBDII code check and it told me that cylinder#5 has been
> > misfiring. Since I never changed the plugs (after 100K miles), I
> > changed all 8, and the problem went away for a few weeks. Now, the
> > same cylinder is misfiring again.
>
> > What I also noticed is that when the car is in the garage for more
> > than a week, the misfiring always happens on first (cold) start. If I
> > use the car the next day, all is OK.
>
> > Should I change the coil as well or the wiring harness (which seems
> > like a huge pain to do)???
> > Thanks
> > Mark
> > 2000 GT 'vert
>
> Exchange the coil pack with another cylinder and reset the PCM. If the
> problem moves it's the coil pack. If it stays on hole number 5 there
> it's a different problem. You could then do that same swap with the
> injector to eliminate/verify an injector problem.
>
> Dan
> 2003 Cobra Convertible
> With Some Stuff and Things

Good advice (should of thought of it myself). Not sure how to swap the
imjector though. Isn't it integrated into the fuel rail thingy?

Un-freakin'-believable!