[s-cars] help with a suspected bad coil.

[chris chambers]

James,

This is what I did, FYI this procedure does require a helper.

Get an adjustable gao spark tester like this one, they are cheap:
http://us.st11.yimg.com/us.st.yimg.com/I/sjdiscounttools_1907_54559075
FYI I purchased mine at auto zone. 

1. unbolt coil pack from engine
2. position the coil pack so spark plug connectors are pointed up,
balanced on a piece of wood (wood is used for insulation)
3. Attach the clip to a good ground (I used a suitably thick piece of
wire to attach to my ground point and then clipped the clip to the
wire, this way I could unclip the wire and adjust the gap easier)
4. Press the other end of the tester into the spark plug boot 
5. Have your helper turn over the engine while you observe and confirm
there was a spark. 
6. Move spark tester to next cylinder and repeat test, after confirming
each of the 5 cylinders all have spark increase the gap on the tester
and retest each cylinder. 
7. Keep repeating this test until you get a cylinder that fails while
the others still have spark, you have identified the weak coil.


HTH

Chris




--- james McCarthy <jjssmccarthy at yahoo.com> wrote:

> Ok folks - could use some help.  The sedan (95.5) has
> developed a stumble - at idle and through all range of
> rmp.
> I'm pretty sure it's a coil.  Here's why...
> new plugs (1 week)
> new plug boots (24hrs) 
> swapped new pos in both slots - no change...
> so tonight I pulled the coil harness (all 5 coils and
> the cover) out of the avant (also a 95.5) and stuck in
> in the sedan - stumble is gone.
> So got to be the coils right?
> But when I unplug the injectors one by one -  all seem
> to degrade performance. So I suspect a coil is just
> mostly dead - notcompletely.  How do I figure out
> which coil is dying???
> For what it;s worth the sedan is running stock
> software with a FMIC and stromung exhaust.
> TIA
> -jamie in houston
> 
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