Ignition Coil Test

Can someone tell me how many coils or coil packs are on a 2004 taco 3.4 v6 5vz-fe model? And also the easiest way to test them and find the bad one?

 

Three coil packs. Each one fires two plugs. They either work or thet don't. Hope this helps

 

Best thing is to be able to read engine codes that make your CEL on. Because they are 3, they are combined by two cylinders. Something that some people don't know is that the sparks goes trough BOTH cylinder each time, at the same time.

Sometimes it can happen for that reason that you'll received 2 missfires codes for one coil defect.

If the coil is not completely fried and missfires happen only when you are climbing hill or requesting more power it's gonna be pretty have to identify the one to replace by an old way like removing sparkplug wires when the engine is running.

OBD reader is the best solution.

 

If you are getting a CEL for a misfire...you can swap the coils around, reset the CEL and see if the CEL comes back and the misfire has moved with the coil swap.

Then you know you have a bad coil.

 

One bit of information, if you are having any kind of misfire, (backfire) you are putting your cats at risk. depending on the age, and condition of your cats, you can ruin them very fast.

 

In a wasted spark system, the spark plugs fire in pairs even though one is on its compression stroke and one is on its exhaust stroke. The extra spark on the exhaust stroke has no effect and is thus "wasted".
This design halves the number of components in a typical ignition system, while the extra spark, against much reduced dielectric resistance, barely impacts on the lifespan of modern ignition components. In a typical engine, it requires only about 2 to 3kV to fire the cylinder on the exhaust strokes. The remaining coil energy is available to fire the spark plug under compression (typically about 8 to 12kV).


It is difficult to actually test a coil directly in this system. As mentioned above, if a misfire is evident, swap the coils out and see if the misfire moves or remains. Also remember that a misfire is NOT limited to spark. Fuel and compression in a cylinder can affect it as well. (Although the most common failure is spark related)


If you are replacing the spark plugs, I would recommend the plug wires as well with that many miles.