I am not a very active visitor to internet forums. But at those times, when I read them, I have a lot of emotions. And a lot to say. 

This time, I decided to check what happened in the ignition coil “industry”. Some people are making homemade kits. Kits, with which the ignition coils, intended for B series engines (and others too), can be installed on, for example, N54 series engines. Or even more extreme: M50/52/54. In this case, an ancient past meets the present. The main argument is that the more powerful the ignition coil, the better!

I have a lot to say regarding these “kits” and other solutions. But the most extreme I read: 

A bit later, such an image was posted.

It turns out it’s not a unique case. There have been many experiments with ignition coils, which resulted in fire!

Of course, there are a lot of potential fire causes under the hood. For example, fuel supply. But this time, the topic is – can the car burn down due to ignition coils?

The answer is… “Yes” and “No” at the same time.

Part “no”. The ignition coil itself (if it’s not a completely “shady” product) can not create such a shortcut for it to catch fire. Also, if the connection defect is created in the ignition coil, the fire will not occur. Even if the full energy leak happens in the ignition coil (all stored energy will not be conducted to the spark plug but will “jump” to the ignition coil itself), the ignition coil will not catch fire. Well, there is a disclaimer – ignition coil of a known/large brand or offered by BMW. In these ignition coils, non-combustible materials are used. Materials that can “handle” large electrical voltages/potentials. China fakes can bring surprises. This section of the “no” answer does not apply to them. Yes, in theory, China fakes can start to burn (especially in modes when DME, by noticing the misfires, starts to “dry” the spark plug). 

Part “yes”. Different engines have different ignition coils. The appearance of these ignition coils is different. But the most important thing is that the electrical parameters of these ignition coils are fundamentally different. Dwell times of the ignition coils are almost similar for M, N, and B series engines (2 .. 2.5 ms). However, the energy accumulated by the ignition coils is significantly different. How is that possible? Very simple – the larger the current during dwell time, the larger the energy is accumulated in the ignition coil. 

The parameter which defines how large current will flow in the ignition coil is the inductance of the primary winding. If for M series engines, this parameter was 5 .. 6 mH, for N series engines around 3 mH, then for B series engines – only 1 .. 1.5 mH. Accordingly, the current during dwell time has increased from 3 .. 5A to 15A.

At this moment, we come to the first problem – a more powerful ignition coil creates a much larger load on DME. To the DME Ignition switch. What are the consequences if the Ignition switch is overloaded? The switch is damaged. With a probability of 99.9%, the defect manifests as short-circuit. A short-circuit in the Ignition switch means – all onboard voltage is continuously supplied to the ignition coil. In the coil, the large heat capacity of 150 .. 200W is released. The insulation of the wires starts to melt, and the body of the ignition coil starts to melt. Yes, such a defect can cause a fire.

Note: each ignition coil doesn’t have a separate/individual fuse installed, and this is the cause of why, in case of such a defect, the connection is not disconnected. 

First major conclusion – more “powerful” (as intended by the manufacturer) ignition coils MUST NOT be installed. Yes, such an act can cause a fire!

A second topic – respectable manufacturers in their ignition coils use materials that are non-flammable and are good insulators of electrical energy. These materials are continuously upgraded and are undergoing serious tests. The body of the ignition coil and other parts should endure even 30.000 V voltage in high temperatures (work temperature can reach even 120 .. 150 oC).

What do you think, what are the parameters for this spare part:

This spare part is taken from “another application” and will now be used in the kit of the ignition coils. The author notes that it “covers the spark plug well”. What about thermal durability? What about the parameters of the electrical insulation? What about the resistance against oil and fuel? As shocking as it would be, the author of this “kit” hasn’t even tested anything of it, not even talking about some kind of certificates or Datasheet compliance. Yes, the use of such a “solution” is the shortest way to the fire!

Conclusion No.2: materials or spare parts intended for “other applications” CAN NOT be used in the ignition system. DO NOT not use the ignition coils of cheap and unreliable manufacturers. All this can cause a fire!

Third topic – keep away from the “sport”/”tuning” ignition coils! The basic information I already mentioned here. This time, the confirmation of what I wrote before – honest posts from Vargas TurboCharger Technologies.

Here, this company honestly admits – they are not manufacturing the ignition coils by themselves but ordering from the manufacturers. What kind of manufacturers? Bosch? NGK? Of course – no! They order from small Chinese factories that offer to fulfill the “OEM” orders, too. These are the manufacturers who offer – “order 500 ignition coils, but in your color of choice and your inscriptions”. Do these manufacturers use the newest, best materials? Some specific technologies? Of course – no.

Does this – a USA-based company – have some unique laboratory that tests the ignition coils? Such a lab would cost several tens of millions of USD. If there would be such a lab – there would be numerous images and posts. And the coils would not cost USD 20. Without any illusions: the only testing is – ignition coils installed for personal and friend’s BMW, and – if it works – excellent! The product is born! 

I have a question regarding this painting – does the used color endure high temperatures, and is it non-flammable? Of course, no one has checked anything like that… 

But, with all respect to this USA-based company:

Here is an honest answer – no power increase. A bonus point from me for this. True thous, everything is spoiled by the obstacle that they sell a “product” of indeterminable quality with unknown technical parameters and safety. But – the body in the customer’s color of choice!

What is the summary? Please don’t perform the experiments with your car! The consequences can be harsh. Install OEM ignition coils!

Yes, I already hear the skeptics – “But I will install the most powerful Ignition switches on the DME of my car, and then…”.

Unfortunately, the situation here is not so simple.

a. in old DMEs, there can be Ignition switches of another type (not IGBT/Eco Spark); changes should be made to their control schematics. The everyday user and “forum specialists” will not be able to do that:

b. even if more powerful Ignition switches are installed, the amount of heat released in them increases significantly. DMEs of older generations are not intended for “consuming” such heat energy. As a result – the more powerful switches will overheat, and consequences – a short-circuit, even – fire is possible;

c. even if you manage to dissipate the increased amount of heat, you have to think of the ability of PCB traces, connections, wires, and connectors to conduct the large power/current to the ignition coils;

d. the most complicated – management of the Ignition switch defines how fast the switch will open or close. This time, instead, it is very important for the switch not to overheat (if it closes too slowly) and – not to overheat if the switch closes too fast and works in a harsh “clamp” mode. Creating the right management – only a powerful development engineer will be able to do it. Anyway – the replacement of Ignition switches is NOT “plug and play”;

e. if DME uses multi-ignition, the installation of more powerful ignition coils leads to COMPLETELY incorrect performance mode. The magnetic material of the ignition coil saturates, and from that moment, the current in the connection increases strongly. What is even more harsh – all energy is not accumulated in the ignition coil but is released in heat! Such mode – fast track to the damages to the Ignition switch and the ignition coil itself. And then – only one set to till the fire. 

In conclusion. Like a trifle, that is not a trifle. 

The author of the idea offers to use such “convenient” connections: 

I say – DON’T use these connections in the automotive industry! In these connections, the soldering material with reduced melting temperature is used. In the engine compartment, the work temperature can reach more than 100 oC (not counting the heating of wires and connections themselves), and such connections are not safe!

I suggest not using these connections in an “everyday” environment. The reason is simple – the visual inspection of the soldering quality is not possible. More simplified – you will not see how correctly/ successfully the wires have been soldered. 

Attention: important information in the 2nd part (here).