BMW Ignition Coil Bench Testing procedure.

Hello all,

   Attempting to develop a technique for bench testing bmw ignition coils. These are the rod type ignition coils (Delphi PN 12 13 8 616 153). They are shielded and attempting to use a paddle probe for secondary ignition pattern when installed on vehicle does not work. The best thing I have found is to use low amp probe and clamp around the supply wire for coil and check current ramp. I will attach pictures of wiring diagram, a scope capture of a shorted and a good ignition coil. You can see that when these coils fire, they fire at nearly 10 amps, so this is not a circuit that you could fire off using just a test light.

   What im trying to develop is how to bench test the coil. I have connected the coil to a battery outside of vehicle, with a spark plug installed and grounded to battery.and CANNOT get it to fire. Could you please review wiring diagram and let me know if you have any ideas how to Bench test it?

My connections were as follows: 

1. Pin 3, fused link straight to battery
2. Pin 2, wired straight to battery ground.
3. Pin 4, is the spark plug, i have grounded the threaded portion of plug straight to battery ground.
4. Pin 1, using a jumper wire, attempt to quickly tap to battery ground to build magnetic field in coil. When doing so you can see the connection spark, and ignition coil will get warm if repeatedly doing it. However you cannot get coil to fire. I have tried on 6 different coils, several of which i know for a fact are good coils and are not shorted.

Thanks for your time and ideas,
Ted


 

Why reinvent the wheel? The B in BMW is for Bench, right?
I like an adjustable spark tester like this one for coils that break down under load. You can really stretch out the spark and stress the coil like it would be under high load conditions, for when the misfire just isn't present at idle in the bay. 
Never missed a weak coil with this tool.

Hello Noah,


   The hope of bench testing is being able to use a paddle probe and check the secondary pattern. When these coils are removed you can hold it to the side of the assembly and achieve a reading. This has been verified by using a secondary extension wire between coil and plug. Take the vehicle currently being repaired for example, 2021 bmw 750. The coolant bottle must be removed to reach coils, no coolant can be spilled because it can damage injectors and or ignition coils which are directly under the bottle. Extreme care must be taken to ensure none is leaked. Pictures attached. While it is agreed that the suggested tool is great for identifying bad coils, alternate testing procedures are being sought due to coil removal being labor intensive. 

   Customers may not understand the scope pattern when shown, however if coil can be proven to be bad on the bench they are much more likely to understand.

Thank you,
Ted 

I see! I was picturing an inline six engine where they are relatively easy to access.

Bought this device on eBay and it works to test the coils! Scope signal of amperage waveform attached! Instructions are translated poorly but the device can be used!

Ted

Perhaps your initial make shift setup was missing a condenser or capacitor that would normally be inside the engine computer.