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.

Spark Control

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 page.

Ignition Coil

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.

Spark Plugs

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 plug)
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.
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This page is maintained by Russell W. Knize and was last updated 06/03/99. Comments? Questions? Email minimopar@myrealbox.com.

Copyright © 1996-2003 Russ W. Knize