Strange 944 misfire

[Jacquiles]

I think i may have figured it out, or at least narrowed it down. When i replaced the spark plug, coil, and plug wires, the coil i replaced it with was a msd coil. this came from a kit made by lindsey racing. After wiggling every and every wire, taking my whole engine harness out and cutting back the wrap on it to try to find broken wires, i noticed that if i pushed my msd coil a certain direction, the problem i was having would show up. idk would drop and it would struggle to live. and i noticed i could see little arcs going from the msd coil itself to the chassis. Idk what exactly is causing it but im 85% sure thats what is causing my problem. If i take the coil out of its little mount it never has a problem but if i put it back in and move it around, it consistently and repetitively will start to present the problem i was having originally.

[yugami]

That's generally a sign the casing is cracked someplace

[michaelmount123]

Isn’t there an issue with running a MSD coil with a 944?

[Tom]

Isn’t there an issue with running a MSD coil with a 944?

Some can draw too much current all at once and fry the DME's ignition transistor. I use a good 'ol MSD 6A red box with HVC-II MSD coil. Lots of more exotic ignitions out there, I know, but his seem to hold up to just about any power level I can throw at it. Hard on the cap, rotor, wires, and plugs though...

[Jacquiles]

Isn’t there an issue with running a MSD coil with a 944?

Some can draw too much current all at once and fry the DME's ignition transistor. I use a good 'ol MSD 6A red box with HVC-II MSD coil. Lots of more exotic ignitions out there, I know, but his seem to hold up to just about any power level I can throw at it. Hard on the cap, rotor, wires, and plugs though...

Ahh interesting. i hope mine isn’t causing any damage to my DME
I’ve had it on for about three months driving it very regularly and no issues yet. other than it arcing to the body of the car. I still don’t know why it was arcing through the case, and it seems to do it from any contact point of the case. I will say, it’s not arcing far, it has to be touching the metal or within like half a millimeter. My “fix” was to wrap it in 2 layers 3m Super 88 electrical tape. Works great now, but still worried what would be causing it to arc through the case of the coil. maybe i should get a new coil?? It never had this problem with that coil until recently, although it’s possible it would have done it from the very start but just wasn’t in just the right spot/conditions for the problem to occur

[Tom]

Isn’t there an issue with running a MSD coil with a 944?

Some can draw too much current all at once and fry the DME's ignition transistor. I use a good 'ol MSD 6A red box with HVC-II MSD coil. Lots of more exotic ignitions out there, I know, but his seem to hold up to just about any power level I can throw at it. Hard on the cap, rotor, wires, and plugs though...

Ahh interesting. i hope mine isn’t causing any damage to my DME
I’ve had it on for about three months driving it very regularly and no issues yet. other than it arcing to the body of the car. I still don’t know why it was arcing through the case, and it seems to do it from any contact point of the case. I will say, it’s not arcing far, it has to be touching the metal or within like half a millimeter. My “fix” was to wrap it in 2 layers 3m Super 88 electrical tape. Works great now, but still worried what would be causing it to arc through the case of the coil. maybe i should get a new coil?? It never had this problem with that coil until recently, although it’s possible it would have done it from the very start but just wasn’t in just the right spot/conditions for the problem to occur

If you have the round canister Blaster-2 type coil that fits a factory coil wire, I doubt that is posing any significant threat to you DME. My comment was really about the bigger coils, like the one I use (pictured below). That said, if yours is arcing from the case, that means something is wrong with it and it should be replaced. Personally, I'd replace it with a Bosch original. I use the high-output MSD parts, because I was previously running a ton of boost with water injection, etc. and putting a very heavy load on the spark. But I can say from first-hand experience that the MSD stuff just isn't as reliable as the factory parts. And, if the factory ignition is in good working order, I doubt you'd see any measurable gains using the Blaster 2 over the factory coil, assuming your car is a typical of the breed.

[Jacquiles]

The cause of this was my MSD ignition coil, which I further investigated in a different post