Coil On plug retrofit

[bmwman91]

Also, is the coil-to-plug extension that comes on the coils long enough to reach the plugs?  It is a little tight between the humps on the valve cover to fit the coils far in.  Oh, and so DEFINITIVELY, which coild are going to be used (from what model)?

[D. Clay]

Possibly the reason for shorter life is the coils are subject to engine vibration and heat when used in a coil on plug setup. The tradeoff is performance and elimination of plug wires. This approach has been used for 15 years by BMW. The problems have been pretty much eliminated. There's no denying that the coils last longer in the stock M42 configuration. It seems to be 75% of the fender mount setup. Throw in the cost of M42 plug wires and it's still a lower cost deal.
Reread this thread and this is from BM318ist's post on first page:
"I took e-36 m3 coils popped em on and plugged them in.you have to cut open the factory loom in order for the wires to extend then re-loom them.making a hold down bracket is the trickiest part! you also have to grind the mounting holes a little to fit them securely in the valve cover."

[bmwman91]

Alrighty, I have 4 spare coils from the last car.  I am going to machine off the mounting holes (they are the only part preventing me from fitting in between the valve cover humps.  I will weld on some tabs to secure them to a mounting bracket, and machine the bracket.  My goal is to have the black plastic 'BMW' cover fit back on.

I just need to get coil-to-plug boot thingies that are long enough.  Anyone have dimensions on some (length, not including the top & bottom where parts insert...I want the EFFECTIVE length).  Thanks a million.

[2002maniac]

here are a few pics of a M50 coil modified to fit in the galley.  I had to completely remove the mounting tabs to get it to fit at all.  Unfortunately the connector in the M50 boot does not snap onto the plug like the original plugwires do.  They do need a bracket pushing the coil down onto the plug.  Unfortunately I have no mounting tabs now so I'll have to come up with something different.
 

[bmwman91]

So, the boot does fully seat on the plug?  Are you sure the reason that ti is not staying seated is not just because it si not long enough to fully engage?

[zerofreez]

Did you check to see if the coil was functional after you modified it like that?  I would have to think that the magnetic field in the coils primary circuit would be weakened by modifiying it like that.

I guess the only way to find out is to get a spark tester and see how far the spark will jump before modification, then try it with the same amount of gap after modification and see if it will still jump that distance.

[2002maniac]

So, the boot does fully seat on the plug?  Are you sure the reason that ti is not staying seated is not just because it si not long enough to fully engage?

I pulled the plug out to make sure

[bmwman91]

Excellent Smithers......

As far as the effects of chopping those tabs off, they are probably minimal to nonexistant.  The wire windings inside generate the magnetic field, and the outer steel wrappings just act as a big transmitter for the magnetic field.  As long as the main portion is still intact, I doubt there would be any effect.

[D. Clay]

So much for the question of whether Bremi's are as good as BMW coils. It seems the answer is do you want to read the first or third line. It looks like only the ears of the mounting tabs were ground off (first photo of coil-on-plug post) and that there is no reduction in the effective area ot the steel wrappings:


You could hold all four coils down with one piece that attached to the valve cover bolts between the end spark plugs that also had the slots for the factory cover. Perhaps someone with a TIG welder.......

[bmwman91]

Interesting note:

I was checking around looking at coild, and after some quick PN checking:
The Bremi coils used on the M42 are the same PN as those used on the M/S50 engines.  Soo, I guess all you need to do is buy the boot and hack up your stockers if you want?

I still think I am going to look for smaller units that do not require as much chopping.

[nickmpower]

i think thats an error? at least the connectors are different arent they?

[bmwman91]

i think thats an error? at least the connectors are different arent they?

Well, I thought it was an error as well, initially.  I was looking through realoem and saw that there was a coil-to-plug boot in the ignition ciol diagram for the M42.  Pelican Parts' picture of the S50 coil was strikingly familiar looking...so i cross referenced the PN's & sure enough, same PN on the different vehicles.  Not only that, but when you do a search for the PN for the boot, the part is listed for the 318iS.

If you search Pelican in the root BMW level, it will shot the result as an E36 part, but if you click on the part, it goes into the E30 section & is titled a part for the E30.  I just ordered new valve cover gaskets and 4 plug boots.  I also informed them of the discrepancy.

I guess I just have to go get a set of helicoil inserts to repair the like 9 stripped valve cover bolt holes in the head, and I am all set!

[D. Clay]

People have been posting that the coils are the same ever since I have been lurking on BMW forums. The similarity has been noted several times in this thread alone. It seems the choice is grinding off the mounting ears of the M50, S50, M42 or "whatever you want to call them" coils and having plug and play electrically or finding smaller coils with a suitable  extension and hoping you don't have to chop up your wiring harness too much. You still need something to secure either one. K.I.S.S. Those photos tell me all I need to know.

[bmwman91]

Here is a solution.  Weld together a bracker that will secure all 4, weld on mounting tabs to the 4 coils, and screw them together.  Where to mount from there?  Drill as deep as you can into the heads of the 2 valve cover bolts in there, tap the holes, then bolt the bracket assembly onto those tapped boltheads.  Simple enough, and should provide adequate support.  The things do not have to be held on with much compression, just held down so a bumpy road cannot jump them off the plugs.

[zerofreez]

Yeah, I got one of my boots today, definately long enough, but a bracket is definately needed.  The boot does not clip onto the top of the spark plug.  It has a spring inside that requires the coil be bolted down to somthing.

Also, the 28 year master tech at my work said that those metal "brackets" are what picks up the colapsing primary magnetic field and fires the secondary.  He said that it would definately effect performance if they were modified.