[DeTomaso] more evidence I'm a not much of a mechanic...

[Tomas Gunnarsson]

I have a feeling that such a gizmo detects current in the wire, not spark
per se. That means that a shorted out plug will indicate as "fine". With a
shorted out plug there's still a spark generated inside the distributor cap
(if the car is so equipped) btw.

Tomas

-----Original Message-----
From: detomaso-bounces at realbig.com
[mailto:detomaso-bounces at realbig.com]On Behalf Of Asa Jay Laughton
Sent: den 20 februari 2010 07:07
To: De Tomaso List
Subject: Re: [DeTomaso] more evidence I'm a not much of a mechanic...


He needs to do two things here:

- Determine if the plug is firing, you can do that with the little gizmo
I was talking about, and yes, it -only- works if there is spark as far
as I know.  If the plug is grounded or not firing, it won't show the spark.
- Figure out which cylinder is causing his mis by -removing- the spark
from each cylinder one at a time.

It may be spark related or it may not be.
It could be a plug not firing, or it could be an intake valve not opening.

He wants to warm up the engine and then remove spark from each cylinder
one at a time to see which one -doesn't- make a difference.  Then he'll
know which cylinder is affected.

But with an MSD box, I don't think it's a good idea to pull the wires.
Though if you do, do it quickly and I'd recommend some spark plug boot
pliers to do it with.  You don't want the MSD box trying to seek a new
ground very long, or it will find it.

What you really need is an engine analyzer/scope kind of deal.
Asa Jay

Asa Jay Laughton, MSgt, USAFR, Retired
& Shelley Marie
Spokane, WA
******************************
http://www.asajay.com   ***   http://www.teampanteraracing.com




Julian Kift wrote:
> I fail to see the benefit of pulling a plug wire and testing it to ground
as that's no different than the gizmo that detects current in the wire
(albeit the gizmo is a lot safer for you and your MSD). If the problem is
not the electronic ignition it's just gonna tell you all 8 wires are fine.
Even if you pull a plug and ground it to see if it sparks or not, that is
also no guarantee it is not faulty as I have known plugs that look good and
are failing under compression.
>
>
>
> IMHO I'd buy a set of 8 plugs and swap them all out, what are they about
$3 ea.
>
>
>
> Good luck,
>
> Julian
>
>
>> From: chrisvkimball at msn.com
>> To: asajay at asajay.com; detomaso at realbig.com
>> Date: Fri, 19 Feb 2010 20:40:54 -0800
>> Subject: Re: [DeTomaso] more evidence I'm a not much of a mechanic...
>>
>>
>> That's exactly right--I don't want to pull the plugs since that's such a
royal pain in the rear. If I did pull a plug, it would be no problem, since
then the ground would be easy; the plug casing grounded with the wire still
hooked up would simply let me see the spark plug sparking its little heart
out...
>>
>> The problem with the signal sensor you mention is that it only shows the
power, not whether or not the plug is firing. I'm pretty sure the electronic
ignition is not the problem. Once I figure out which cylinder it is, then I
can pull the corresponding plug and see what it looks like.
>>
>> It seems as if I just take off a plug wire and make sure it doesn't touch
anything, that shouldn't hurt anything, should it?
>>
>> Thanks,
>>
>> Chris
>>
>>
>>
>> Sincerely,
>>
>> Chris
>>
>>
>>> Date: Fri, 19 Feb 2010 20:30:02 -0800
>>> From: asajay at asajay.com
>>> To: detomaso at realbig.com
>>> Subject: Re: [DeTomaso] more evidence I'm a not much of a mechanic...
>>>
>>> Jack, the trouble is he doesn't want to pull the -plug-, just the
>>> wire. I'm not sure how I'd do that with an MSD.
>>>
>>> My dad used to have this cool little gizmo. It looked like a pen but
>>> was actually a spark detector. You held it next to the plug wire and it
>>> would flash in time with the energy going to the plug. Something like
>>> this would at least tell you there is spark going to each plug.
>>>
>>> Have you tired pulling the plugs to inspect them? Sometimes just
>>> looking at the plugs will tell you what's going on.
>>>
>>> Asa Jay
>>>
>>> Asa Jay Laughton, MSgt, USAFR, Retired
>>> & Shelley Marie
>>> Spokane, WA
>>> ******************************
>>> http://www.asajay.com *** http://www.teampanteraracing.com
>>>
>>>
>>>
>>>
>>> JDeRyke at aol.com wrote:
>>>
>>>> In a message dated 2/19/10 6:28:19 PM, chrisvkimball at msn.com writes:
>>>>
>>>>
>>>>
>>>>> when you say I should run the spark plug wire to ground, do you mean
that
>>>>> once I remove the wire from the plug I should actually run the spark
plug
>>>>> wire directly to ground, and that won't damage anything?
>>>>>
>>>>>
>>>>>
>>>> Attach a ground wire with an alligator clip to the ground lug on the
plug
>>>> base so the plug works normally but is outside the engine. Otherwise,
the
>>>> built-up energy in the MSD and coil will have no place to go .... until
it
>>>> punches a hole in a circuit board to ground inside the box. Good luck-
J DeRyke
>>>> _______________________________________________
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