Upgrading The Ignition System
[ Spark Control | Ignition
Coil | Distributor | Wires
| Plugs ]
This page describes the options available for upgrading the ignition system
on 2.2L and 2.5L engines.
On all fuel injected engines, spark is controlled by the computer.
It automatically sets the spark advance based on its programmed spark curves,
relative to the base ignition timing. On turbocharged engines, the
computer uses a detonation sensor
to measure the amount of spark knock that is currently being generated.
If knock is too excessive, the computer can reduce the spark advance to
some degree. If you are experiencing spark knock and the sensor is
functioning properly, you can retard the timing some by retarding the base
ignition timing. To learn how to set the base ignition timing, see
the Engine Timing and Belt Replacement
The stock ignition coil has proven to be more than sufficient for any application.
It can produce enough spark even at very high boost and engine speeds.
You can give the coil a greater advantage by relocating it closer to the
distributer. It can be bolted to the AC compressor bracket and the
coil wire can then be shortened. The later model spark coils from
1991 and later are significantly smaller than the older oil-filled type,
but perform just as well. If you can't fit the older stock coil closer
to the distributer, try one of these.
There are high performance coils available (such as MSD), but no gains
have ever been detected with these coils. MSD's other products, such
as their spark booster, have actually decreased performance in many applications.
Keep it simple: stick with the stock coil.
The stock distributer is a simple, no-frills design that does not require
any special attention. Any decent stock replacement cap and rotor
will work fine.
One disadvantage of Chrysler's distributer is that the contacts for
the spark plug wires are the wires themselves. The spark jumps right
from the rotor tip to the spark plug wire connector. If the wire
connectors are badly burnt but the wires are still in good shape, just
pull the wire out (by squeezing the connector tip with pliers), rotate
it 180 degrees and put it back in.
Spark Plug Wires
The stock wires are usually sufficient for most applications. Many
high performance folks go with Magnecore 8mm spiral core wires, which also
have proven to work very well. A fresh set of wires can make a huge
difference if your engine is misfiring. Replace the cap, rotor and
plug, while you are at it.
Believe it or not, there are no magic spark plugs for these engine.
In fact, a set of stock RN12YC Champions or Autolites are the best plugs
you can get. Bosch Platinum core plugs have been known to fall apart
in turbo engines. Avoid them. Also avoid Splitfires, which
are thankfully going out of style. NGK V-Power plugs work well, but
the electrode erodes more quickly because of its sharp edges. You
will have to re-gap them after about 1000 miles. You end up with
a normal plug at that point, so they really aren't worth it. No improvement
in performance was noticed with V-Power plugs.
If you are running high boost, then you will want to run a colder plug
to prevent misfires and detonation. A colder plug has better heat
sinking properties to cool off the electrodes. Too cold a plug will
foul because it is not running hot enough. In terms of Autolite and
Champion spark plugs, here are my recommendations:
Autolite 65, Champion RN12YC for up to 14psi of boost (stock plug)
Autolite 64, Champion RN11YC for up to 18psi of boost
Autolite 63, Champion RN9YC for greater than 18psi of boost (coldest
Autolite 62, Champion RN7YC this plug will probably just foul up, but
it is there
These are just ballpark figures to give you an idea. You can try
running a colder plug and see what happens. If they foul up, go with
a hotter plug.
This page is maintained by Russell W. Knize and was last updated 06/03/99.
Comments? Questions? Email
Copyright © 1996-2003 Russ W. Knize