MyE28.com

I had noticed I had an interesting "wrinkle finish" on one of the last rotors I pulled out of the turbo car. New ignition components always have that smooth, shiny look, so I found this odd. When the head came off a little while ago, I noticed that the rotor that was in there was even worse than the last one. It was actually melted into the end of the cam a little bit. The whole thing looks like its melted on the outside. The car was running pretty good, but I wonder why I'm cooking these rotors? I have a feeling Megasquirt has something to do with it, but other than that I have no idea.

How do you have your ignition control setup with megasquirt?

I'm using the stock BMW stuff. Stock single coil directly controlled. About 2.5ms dwell, I cant remember the spark duration off the top of my head. Its something wacky like .6ms.

Does Motronic use a condenser or a resistor on the primary side of the coil?

altus22 wrote:Does Motronic use a condenser or a resistor on the primary side of the coil?

The primary being the coil the one that generates the spark when the secondary coil is grounded right? If thats the one, then there is no single resistor and no condensor. The ignition rotor has about 1.5k ohms, plug wire sockets have 5k ohms and the plugs have another 5k ohms of resistance. The plugs arent stock though, so I'm not sure if they're providing too much resistance or what.

turbodan wrote:

altus22 wrote:Does Motronic use a condenser or a resistor on the primary side of the coil?

The primary being the coil the one that generates the spark when the secondary coil is grounded right? If thats the one, then there is no single resistor and no condensor. The ignition rotor has about 1.5k ohms, plug wire sockets have 5k ohms and the plugs have another 5k ohms of resistance. The plugs arent stock though, so I'm not sure if they're providing too much resistance or what.

The primary coil is connected to 12V ignition at one end, and to the secondary at the other. The secondary is connected to the primary at one end, of course, and to the distributer at the other. The ECU is connected to the point between the two coils.

The ETM doesn't show a condenser or ballast resistor. If there is a condenser, it would be across the transistor in the ECU, and wouldn't be something you'd normally replace.

The ignition wire is connected directly to the coil, thus there is no ballast resistor.

Thats right. I always forget that the outer terminals are on the same coil.