Other Possible Misfire Causes

Carbon Tracks On The Spark Plug and Spark Plug Boot. How To Test The Coil Pack (1990-1998 Chrysler 3.3L, 3.8L)

So you've done all of the spark tests, and your Chrysler (or Dodge or Eagle or Plymouth) mini-van is still misfiring. Well, here are a couple of suggestions that might help...

  1. 1

    Inspect the inside of the spark plug wire boots and remove the spark plugs to visually check their ceramic insulators for Carbon Tracks

    1. The photos in the image viewer point (the orange arrows) to what carbon tracks look like.
    2. Replace the components as affected with carbon tracks.
  1. 2

    Engine compression test to see if one or several cylinders have low compression.

    1. This is one of the easiest, yet most overlooked test to find the cause of a misfire condition.
    2. You'll need an engine compression tester of course.
    3. The engine between cylinders should not vary more 15%.
  2. 3

    Fuel injector test to see if there's a BAD fuel injector in the bunch.

    1. There are several methods to test them which are beyond the scope of this article but...
    2. The fastest way to test them is checking the resistance (Ohms) value of each one and then comparing them to each other.
    3. Any resistance that's not within the average of the others indicates the fuel injector is fried. If the Ohms values are nearly identical... then the fuel injecttors are OK and not the cause of the misfire.
    4. You can buy a specific fuel injector tester (on line) that activates them by a predetermined pulse width. This tester is used in conjunction with a fuel pressure gauge (which will measure the fuel pressure drop of the activated injector).

Symptoms Of A BAD Chrysler Coil Pack

When the ignition coil pack or the spark plug wires are BAD, your Chrysler (or Dodge or Eagle or Plymouth) mini-van will display one or more of the following symptoms:

  1. The car idles rough and wants to stall (die).
  2. When you accelerate the car, it has no power.
  3. Really BAD gas mileage.
  4. The vehicle will not start.
  5. The car will not run on all cylinders.
  6. misfire codes that are lighting up the check engine light on your instrument cluster.
    1. P0300, P0301, P0302, P0303, P0304, P0305, P0306
  7. Rotten egg smell coming out of the tail-pipe.

Precautions, Do's and Don'ts

The tests you're about to learn are pretty simple and easy but, since most of them are done with the engine cranking... you need to be alert and on your toes. Take all necessary safety precautions to keep your fingers, hands and entire self safe. Here are a few other tips and suggestions:

TIP 1:   The coil pack test described in this article is an ON CAR Test, so do not remove the coil pack from your car or mini-van. The coil pack is removed from the engine, in the photos I'm using, just to make it easier to explain the tests.

TIP 2:   Do not use a regular spark plug instead of a spark tester to test for spark. Using a spark plug to test for spark is the surest way to guarantee a fake spark result that will have you wasting time and money. Use or buy the HEI spark tester.

TIP 3:   Do not remove the spark plug wire from the spark plug or the ignition coil while the engine is cranking to test for spark. This procedure will fry the ignition coil pack and you run the risk of getting shocked.

TIP 4:   It's important that you start your Diagnostic from TEST 1, do not skip around from test to test unless specifically instructed to do so by the TEST you are currently on.

TIP 5:   Do not use a test light where an LED light is called for. Use the recommended/indicated tools for all of your tests