TEST 4: Checking For Leaking Oil/Anti-Freeze
If all of the ignition coils fired off spark in TEST 1 and yet your Ford car or truck is experiencing a misfire condition, then the most likely causes are: 1) the spark plug boots spark plugs have developed carbon tracks or 2) the spark plugs and spark plug boots are swimming in engine oil or anti-freeze (from a leaking intake manifold gasket) or 3) both of the aforementioned conditions. All of these conditions are a very common occurrence in this type of Ford Coil-On-Plug ignition system.
If the spark plug boots spark plugs are swimming in engine oil, it's usually due to the valve cover gasket leaking oil into the spark plug tubes. This oil will cause the ignition system to misfire and/or cause carbon tracks to form as the spark cooks the oil. The solution here is to replace the valve cover gaskets along with the spark plugs and ignition coil boots.
If the intake manifold gasket (which is made out of plastic) is leaking anti-freeze into the spark plug tubes, this will cause your Ford car or truck to misfire. The solution here is to replace the intake manifold gaskets along with the spark plugs and ignition coil boots.
In the image above, you'll see what a carbon track looks like on the spark plug boot and on the spark plugs. The next step is to remove the spark plugs and spark plug boots to visually inspect them for carbon tracks and/or to see if the are all oil-soaked or anti-freeze soaked.
If the spark plugs are oil-soaked and/or anti-freeze soaked and/or with carbon tracks, you'll need to replace them all along with the spark plug boots. Failure to replace one without the other will only make the carbon track return and/or continue to misfire still.
Now, if no carbon tracks are visible on any of the spark plugs, or spark plug boots, then the ignition system is not the cause of your misfire condition. I would check engine compression and the fuel injectors among several things. Go to: TEST 6: Other Common Causes Of A Misfire.
TEST 5: Doing A Cylinder Balance Test
As stated in the beginning of the article, you don't need a scan tool to find out which cylinder or cylinders are the ones misfiring. But, if you have one, read on anyway. This info will help you to add to your ‘toolbox of know-how’.
The main reason why you should perform a cylinder balance yourself and not rely on a scan tool to identify the misfiring cylinders (on a Ford) is that in many cases it takes the fuel injection computer too long to set the misfire code and a lot of times, it may not be the correct one. Therefore, knowing how to perform a simple cylinder balance test (with tools that are not going to break the bank) becomes important.
To perform a cylinder balance test, you'll unplug one fuel injector at a time to see if you can hear/feel a drop in engine RPMs and a drop in engine vacuum (as measured using a vacuum gauge).
The vacuum gauge is not an absolute necessity to perform the cylinder balance, but if you use one, it'll help you to visually confirm the drop in engine RPM.
The test is done with the engine running. So you have to be careful. Take all necessary safety precautions and use common sense. Also, this method will set some fuel injector codes that you'll have to erase after you get done. Alright, here's the procedure:
NOTE: The instructions below call for a vacuum gauge. If you don't have one, don't worry about it since you can still perform the cylinder balance test without one.
- Connect the vacuum gauge to an available vacuum hose that has vacuum at engine idle (if you have one). You can connect the vacuum gauge to the plastic vacuum line that feeds the EGR vacuum solenoid.
- Start the engine.
- Disconnect one fuel injector and notice if:
- You can hear/feel a drop in the engine RPMs and
- See if the vacuum gauge needle drops (if you're using one).
- Again, what you're looking for is if disconnecting the fuel injector causes a change in the hum of the engine (RPM drop) and a change in the vacuum gauge's needle.
- Unplug and re-connect the same fuel injector connector as many times as you need to to get a result you're sure of.
- After you're sure of your result, re-connect the fuel injector and go to the next one.
- Repeat this with all of the remaining fuel injectors.
OK, now that you know what cylinders are ‘dead’ (or in other words: not contributing power), you can now test the Coil-On-Plug ignition coil that supplies that cylinder with spark to see if it's the cause of the problem. Go to: TEST 1: Checking For Spark.
