TEST 3: Swap The ‘No Spark’ COP Coil
So far, in your testing, you've found a COP ignition coil that isn't sparking. To make sure that this particular COP ignition coil is getting all of its signals (remember, the COP ignition coil has a connector with 3 wires), I recommend you swap this coil with another. No, I don't mean going out and buying a new one. I mean simply swapping this ignition coil with another one that's already on your Nissan's engine.
Just to explain in a bit more detail what we're trying to accomplish, the idea behind this ignition coil swap is twofold:
- We're gonna see if the non-sparking coil will now spark when connected to another electrical connector.
- See if the other ignition coil (that is sparking) will spark in the non-sparking coil's electrical connector.
Why this extra step? Again, this is just to make sure that the non-sparking ignition coil is getting all the 3 signals it needs to spark (these 3 signals are: power, ground, and the triggering signal).
Alright, this is what you'll need to do:
Disconnect and remove the COP ignition coil that did not spark.
Choose one of the other COP coils that is Sparking and remove it from its place.
- If you need to make sure that this COP ignition coil is sparking, you can test it with your spark tester.
Once the good COP coil is removed, place it in the location of the bad COP ignition coil.
- Next, connect the HEI spark tester to this COP coil.
- Ground the HEI spark tester with a jump start cable directly on the battery negative (-) terminal.
Now, place the bad COP ignition coil in the location of the good one you just removed and bolt it down.
Once everything is ready, have your helper crank the engine.
What you need to see is:
- That the good COP coil is still sparking
- This would confirm that the 3 signals are present in the COP coil connector.
- That the good COP coil is still sparking
Let's take a look at your test results:
CASE 1: The COP ignition coil sparked. This tells you that the COP coil that did not spark in TEST 2 is bad and needs to be replaced.
Here's why: By placing a good and sparking ignition coil in place of the bad one and having spark come out of the good one, then this proves that:
- It's getting power (10 to 12 Volts).
- It's getting the PCM's Triggering signal (known as the IC (Ignition Control) signal).
- It's being fed with ground.
CASE 2: The COP ignition coil DID NOT spark. This tells you that the reason why the COP coil did not spark is because it's lacking one of the 3 signals it needs to spark.
The next step for you is to:
- Check that the ignition coil is being fed with power (10 to 12 Volts).
- That the PCM's is providing Triggering signal (known as the IC (Ignition Control) signal).
- That the ignition coil is being fed ground.
Although these specific tests are beyond the scope of this article, you now have an idea of what direction your diagnostic/troubleshooting needs to go in.
TEST 4: How To Do A Cylinder Balance Test
It happens quite a bit, that even though the car is suffering a bona-fide misfire, the fuel injection computer (PCM Powertrain Control Module) does not set a specific misfire code. If this is happening in your specific situation, there's a simple way to find out which cylinder is the one that's ‘dead’ (misfiring).
To find the ‘dead’ cylinder you need to do a cylinder balance test. The cylinder balance test simply involves disconnecting one fuel injector at a time (while the engine is running) to see which one doesn't have an effect on the engine's idle when unplugged.
NOTE: You can also disconnect the COP ignition coil's connector, although this is not the preferred method since it loads up the cylinder with excess gasoline.
This is what you'll need to do to perform a cylinder balance test:
Start the engine and let it idle.
NOTE: This test is done with the engine running. So be careful, stay alert, and think safety all of the time.
Disconnect one fuel injector at a time.
- What you're looking out for is the fuel injector that DOES NOT make the engine's idle worse (when you unplug it from its connector). If this happens then this cylinder is the ‘dead’ one.
- In a good cylinder (one that's contributing to engine power), when you unplug the fuel injector from its connector, the engine's idle will get worse. It'll be very noticeable!
Once you've tested all of the cylinders in this way, write down the cylinder's number who's unplugged injector did not make the idle worse.
Let's take a look at what your cylinder balance test results mean:
CASE 1: Unplugging a fuel injector had NO EFFECT on the engine's idle. This test result tells you that that particular cylinder is ‘dead’
You can now start from TEST 2: Check The Ignition Coil For Spark and check to see if the COP ignition coil is bad or not.
CASE 2: Unplugging all of the fuel injectors (one at a time) had NO EFFECT on the engine's idle. This tells you that all of the ignition coils and fuel injectors are working as they should.
If you're still experiencing a rough idle condition then more likely than not, one of the following problems applies to your Nissan:
- One or more engine cylinders have very low compression or the individual compression of the cylinders varies more than 15%.
- Vacuum leak from leaking intake manifold gaskets or vacuum hoses.
- Dirty fuel injectors.
Although testing the above conditions is beyond the scope of this article, you now know in what direction you need to take your troubleshooting.
More 1.8L Nissan Tutorials
You can find a complete list of tutorials for you Nissan 1.8L equipped car here: Nissan 1.8L Index Of Articles.
Here's a small sample of the tutorials you'll find in the index:
- How To Test For A Blown Head Gasket (Nissan 1.8L).
- How To Test The Starter Motor (2000-2002 1.8L Nissan Sentra).
- How To Test Engine Compression (Nissan 1.8L).
- How To Test The 2000-2002 Nissan Sentra 1.8L MAF Sensor (at: easyautodiagnostics.com).
If this info saved the day, buy me a beer!