RE: [DML] Re: Engine misfiring and coils

["John Hervey" <john@xxxxxxxxxxxxxxxx>]

Group, There is a saying if you keep on doing what your doing, then you keep
on getting what you got. So, the question is are you happy with what you
got.
If your happy with the perfectly good conservative Bosch ignition system,
then I would keep on buying it. It's easy for people to sit and criticize
the parts when they haven't done any testing or research on them at all.
It's easy for some to criticize the ignition system for problems when you
may have a fuel delivery problem. And we sure can't blame the coil when it's
hooked up wrong. I'll say it this way since we can't look inside the
cylinder. If fire and fuel meet in a compression stroke then there is an
explosion.
With that said, here is the skinny on the coils:
 It's a coil of wire that has a primary and a secondary winding and it
doesn't know whether it's on a Delorean or a Porsche. The coil hasn't
changed much since the Model T car so it isn't rocket science.
The Delorean stock coil has a primary resistance of .7 ohms and the MSD also
has a primary of .7 ohms. But, since the MSD coil has a higher ratio of
windings between the primary and the secondary, hence a higher output
voltage. MSD recommends that a .8 ohm external ballast resistor be used with
the coil and we have a 1 ohm on the fire wall unless it's bad.
Race car drivers use them like popcorn and coupled with the proper wires you
will have a positive firing and more powerful firing system to burn the fuel
more effectively.
The 8mm low ohm wires are also the standard HP wire used in most modified
street cars and most general race cars. Low ohm wire again is used by people
requiring a hotter spark and more effective fuel burning.
The Pertronix coil which is more favorable to the stock wires has a higher
resistance of
1.5 ohms and has a primary vs. secondary windings rated to 40,000 volts and
that's what I would recommend with stock wires.
Also keep in mid that now having a more powerful ignition system and a more
positive firing system will now bring out the flaws in the fuel delivery
system. It will also find little problems easier that the forgiving stock
ignition system.
Some of the problems could be a defective plug, defective wire, bleed over
from wire to ground at higher RPM's, fuel injectors not balanced out and one
is delivering more fuel than another, What else ???.
Bosch was the original plugs used on the car. Going to the Bosch Platinum +
4 again is an up grade to the stock plug.
To me the best way to find the weakest link in a system like Dan's is
possibly a engine analyzer to find the problem.
There are 1000's of MSD and Pertronix coils out there with no problems, so
we just haven't found his particular one.
Here is a link to take a look at.
http://www.msdignition.com/coil_blaster_1.htm

John






-----Original Message-----
From: David Teitelbaum [mailto:jtrealty@xxxxxxxxxxx]
Sent: Monday, June 07, 2004 11:24 AM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: [DML] Re: Engine misfiring-Updated-


This is correct. Recently there was another poster with a similar
problem. He went back to the Bosch coil (again from an MSD) and found
a bad connection or a bad wire going to the coil which turned out to
be his problem. IMHO there is little to gain from an MSD. If you are
really having coil problems I would replace it with another Bosch. A
long shot, but another possability is a plugged up fuel filter or
really dirty air filter. I don't think it is a timing problem with the
camshafts. You could check the spark timing and verify that the
mechanical and vacuum advance is working. Try some fresh gas with 91
octane and see if that helps.
David Teitelbaum
vin 10757


--- In dmcnews@xxxxxxxxxxxxxxx, "Elvis Nocita" <elvisnocita@xxxx> wrote:
> Dan,
> I have no real idea what the reason is for your problem.
> But you can be sure, that the chains didn't skip anything.
> What I would check is - plugs (use the regular ones), ignition coil
> (I don't trust anything that doesn't show BOSCH on it) and the
> fuel injectors.
>
> There was one on the list lately who had a problem with a MSD-something
> coil, too.
>
> 9 of 10 problems are electrical problems. Therefore I suggest to
> check these parts first.
>
> Elvis
>
> > Here is some updates on the problem-The engine only misses at
> >  is
> > fine. Everything check out okay. Only misfires beyond 1/3~1/2
> > throttle, if throttle is below this it will not misfire. The car
> > shakes a lot while it is misfiring. Alternator is
> >
>b
> --
>




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