TEST 1: Testing For Spark At The Spark Plug Wires
The purpose of this test is to find out if:
- All of the spark plug wires are NOT firing spark.
- Or if just some (of all) are firing spark.
- From the results of this test, you'll be able to say if the spark plug wires are bad or if you need to dig a little deeper.
Either way, I'll take you step by step thru' the whole process and you'll be able to pin-point the problem to either a bad igniter (ignition control module), or a bad ignition coil, or BAD distributor cap and/or Rotor, or bad spark plug wires. You will also find out if the problem is due to a broken timing belt.
As a side note, you will NOT be testing the resistance of the spark plug wires, since this is the most useless, complete waste of life method to test for BAD spark plug wires. The spark plug wire test you're about to do is a dynamic test done with the engine cranking. Read on...
Just a friendly reminder: do not use a regular spark plug instead of a spark tester for the spark test and do not pull the spark plug wire off of the spark plug either while your helper is cranking the engine (to check for spark). Ok, here's the test:
- Remove the spark plug wire from its spark plug.
- Attach the HEI spark tester (or an equivalent spark tester) to the spark plug wire.
- Attach the HEI spark tester to a good Ground point, or use a battery jump start cable to attach it to Ground (my preferred method).
- Have your helper crank the engine while you observe the spark tester.
- Repeat the test for all of the remaining spark plug wires.
Let's take a look at what your test results mean:
CASE 1: If you got spark on all of the spark plug wires: This confirms that the ignition coil and the igniter (ignition control module) are working. If your Honda Accord or Prelude is suffering a NO START Condition, this result indicates that the ignition system is not the cause of it.
What I recommend you do, is to do an engine compression test or a fuel injector test. You can find these step-by-step tests at troubleshootmyvehicle.com by clicking here: How To Test A Misfire Condition (Honda 2.2L, 2.3L).
CASE 2: If you got NO spark on none of the spark plug wires: This could possibly caused by a BAD igniter or a bad ignition coil or a bad ignition coil high tension wire. The cool thing is that these possibilities can be tested. Therefore the next step is to test the high tension cable that connects the ignition coil do the distributor cap. Go to: TEST 3: Testing For Spark At The Ignition Coil's High Tension Wire.
CASE 3: If you got spark on some but not all of the spark plug wires: This usually indicates that either the spark plug wires are bad or the distributor cap is bad. It's a common problem for one or two spark plug wires to go bad or for one or two distributor cap towers to go bad and not let spark thru'. 90% of the time replacing the distributor cap, the distributor rotor and the spark plug wires should solve your problem, BUT to further test this, go to TEST 2.
TEST 2: Testing For Spark At The Distributor Cap
In this test step we're gonna' test for spark directly on the distributor cap tower of the spark plug wire that did not spark in TEST 1.
As you can see in the photo above, we're gonna' place the spark tester directly in the distributor cap tower.
IMPORTANT: Perform this test only if one or several (but not all) of the spark plug wires did not spark in TEST 1.
These are the test steps:
- Remove the spark plug wire that did not spark from its tower on the distributor cap.
- Place the spark tester directly on the tower.
- Use a battery jump start cable to hold the spark tester to the tower as shown in the photo above.
- Have your assistant crank the engine while you observe the spark tester.
- You're only gonna' get one of two results: spark or No spark.
Let's analyze each of these results below:
CASE 1: You got spark. Then the spark plug wire is bad, replace them all. This is probably as far as you may need to go since your Honda will probably start after replacing these parts.
Here's why: As the spark plug wire ages, its normal resistance to spark increases to the point that the wire can not and does not transmit the spark to the spark plug. This will either cause a misfire, or a lack of power, or a no start condition. spark plug wires don't last forever, especially after-market ones (average life-span is 3 to 4 years).
CASE 2: You got NO spark. Then the distributor cap is probably bad. I say probably because further testing is required. To further test the distributor cap, go to: TEST 3: Testing For Spark At The Ignition Coil's High Tension Wire.
Here's why: As the distributor cap ages, the terminals that transmit the spark to the spark plug wires corrode. This corrosion increases the resistance to spark and over time (as more corrosion is created) this same corrosion stops the spark from passing thru' to the spark plug wires. The good news is that this condition CAN be tested.