[DeTomaso] Fwd: Re: more evidence I'm a not much of a mechanic...
larry at ohiotimecorp.com
larry at ohiotimecorp.com
Sat Feb 20 11:06:43 EST 2010
Hi Chris,
Pulling a plug wire off for a short time will not be a problem. Keeping it off for a long time can be.
If you are doing this at the cap I would simply ground one end of an old plug wire, pull one wire and
put the grounded one in. You should only do this as the motor is running. It will be much EZer to tell
the difference from one cyl to the next, this way. You can buy or make a fancier tool by putting an
alligator clamp on the side of an old spark plug (providing its ground) clamp that onto the motor and
hook the plug wire to it. You are now removing the spark from the cylinder and can see it jump the
plug gap. Remember that the spark acts differently when under pressure of the cylinder, it sparks
more in that environment.
Yes Ken some old timers still use the engine analyzers with a scope. You can see voltage and duration
that a computer will not tell you. Each of my analyzers, with a scope, have the ability to cut out a
cylinder for this kind of testing. This is very handy in tuning Weber carbs to make sure each is doing
the same as the next carb.
Larry - Cleveland
On Sat Feb 20 2:35 , Christopher Kimball chrisvkimball at msn.com> sent:
>
>I can't believe that if I pulled one wire off at a time from the top of the MSD Ready-to-Run
distributor cap it would cause any harm to the electronic ignition--it seems as if to the system it
would simply "look like" that one spark plug was gapped way too wide, and therefore no spark was
occurring.
>
>I'm really trying to avoid pulling all the plugs--they're less than 1000 miles old, and last time I
changed plugs, it took almost 2 hours. It's those darn passenger-side ones! If I can narrow it down
to just one problem cylinder, then I can pull out the plug and examine it for indications of what's
going on in that cylinder.
>
>If pulling the wires indicates there isn't a problem with the cylinders firing as they should, then
I'll know it's something else.
>
>I could also take off one of the wires with the car stopped, then start the car and simply plug the
wire back into the top of the distributor, then turn the car off and do it again, wire by wire.
>
>Does anyone know if this could cause harm to the system? Without the plug wire flailing all around,
there's no way the ignition could accidentally ground out.
>
>Thanks,
>
>Chris
>
>
>
>
>> Date: Fri, 19 Feb 2010 22:07:18 -0800
>> From: asajay at asajay.com
>> To: detomaso at realbig.com
>> 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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