Need a few photos - M42 guys

[irish44j]

Just tying up some loose ends (literally) to get this engine ready to run. For those who don't know, this was swapped into an M10 car, so the electricals and fittings are totally different.

So here's the overview of the area I'm looking at:



First, this area. I have the plug for the O2 sensor on the right. Does that bracket for it mount someplace? Into that hole in the battery tray perhaps?

Also, the O-connecter - is this a ground, or is this connecting to the battery/power junction thing?



Now the coil wires. The coilpack mounting bracket isn't mounted yet, but it will be. How do I tell which plugs go to which coil? Looks like the wires inside are the same colors on all four. Anyhow have a good specific photo of the orientation of which wires go to which plug?

[Simon S]

Here's mine:



O2 sensor connection mounted underneath. You can see the black mounting clip come up from the underside near the grounding point.

"o-connector" is a ground.

You have my sympathies on figuring out which coil is which.. I know that if you have the cover for the coil bracket, it indicates which cylinder. Seems like I had things disconnected once and was able to see which coil connector went where from natural lengths and bends in the factory wiring.. like they would only connect in one way..

Found these photos which may help:

[irish44j]

Simon, as always you're the man with the right pics :)

That's 2 questions answered at least. Didn't even consider that the mount for the O2 was UNDER the battery tray, lol....For the coils maybe I'll just find a local M42 guy and put the cars next to each other and try to pick the right wires for the coils. It's a 50-50 shot anyhow since the two longer wires obviously go to the backside....just have to figure out which one goes to 1/2 and to 3/4 of the pairs.

Also, considering moving the whole coil pack to the battery tray (where it will get less muddy from rallycross). Thoughts on that?

1. do the coils need to be grounded (e.g. does the stock mounting bracket have any rubber grommets or anything, or is it all metal to metal?)

2. would there be any signal interference from the battery cable, assuming all wiring is good/shielded?

[Simon S]

Simon, as always you're the man with the right pics :)

No problem. Always glad to be of help! I’m stoked for you with your rallycross endeavors.

Also, considering moving the whole coil pack to the battery tray (where it will get less muddy from rallycross). Thoughts on that?

Sounds like a good idea to me. I understand where you’re coming from with mud/dust/dirt protection. Seems like you could fabricate a little box or something for it in that area. Spark plug wire routing might be a little wonky – but whatever on that.. Plus you wouldn’t have to weld on annoying brackets to the strut tower.

1. do the coils need to be grounded (e.g. does the stock mounting bracket have any rubber grommets or anything, or is it all metal to metal?)

2. would there be any signal interference from the battery cable, assuming all wiring is good/shielded?

1. This one got me as I’m not entirely sure.. in stock form, the coil hardware is mounted metal to metal (on body). With a COP conversion, there is also metal to metal mounting (on engine). I'd ground the coil pack hardware just to be safe.



2. I wouldn't worry about signal interference - unless someone else chimes in with more education on the matter..

[irish44j]

fab, now just gotta figure out the wiring. Thanks again!

[Dj Buttchug]

simon again with the killer pics. Irish, your brackets and sunroof crank are on the way. Good progress so far!

[AndrewBird]

Rather then move the coils, why not go coil-on-plug? Get everything out of the way.

[Simon S]

That crossed my mind too, but I think having the protective valve cover "valley box" over plug boots was more desirable than an exposed COP conversion - given that this car sees so much dust/dirt/mud as a rally car.

I think I'm one of the few who bothered attempting use of the valley box on an m42 COP - but even then, it takes hours of work, and the valley box gets hacked up so much in the process that it loses protective worth.

fwiw, changing the plugs or getting the valve cover off becomes pretty annoying with a COP conversion in place..

[AndrewBird]

Yeah, I suppose so. And moving the coils isn't that difficult really.

[irish44j]

Yep, simon's got it. I'd rather have the protective element with all the dirt/dust that gets in there. Plus to be honest there's no real reason to do it for my application - plus I've heard that vibration isn't great for the coils....and this engine on this car with solid mounts will be getting some vibration, lol...

Still gotta figure out the plugs though :P

[irish44j]

so here's how it all hooked up. As Simon noted, it seems to be the "natural" way the plugs go, though I'm not totally sure on the bottom two (on the right). If anyone feels like pulling their coilpack off the bracket and flipping it over and taking a pic, that would be much appreciated :)



here's the bottom two (one I had to tape up since the boot was crumbling...)



everything look correct here?

[Simon S]

Hey Josh,

First off, the spark plug wires in the valley box look right.
Here's a comparison shot of mine if it helps:




After reviewing photos, I'm concerned your coil wires are switched. I’ll post big versions of the photos I have so you can review them with greatest detail.

Terms used:
Coil pack - the assembly of coils which are stacked together like building blocks

Top - with the coil pack in factory location, the "top" coils are closer to the hood, while the "bottom" coils are closer to the ground. #2 is the topmost coil.

Coil harness - the wiring that connects to the coils in the coil pack


Note that coil harness approaches the coil pack from the side – not from the bottom (as in your posted photo).





And then here's a shot of me holding up the coil wires with them labeled:



Note that the shorter wires splitting away from harness go to 1 & 2 (top coils), while the longer ones reach downward, under the coil pack to 3 & 4 (bottom coils)

Good luck.

[irish44j]

ah, that indeed changes everything, in which case I definitely have it wrong. Simon, you just want to drive down here and show me how to do everything? lol....

[Simon S]

ha! I'm not cheap.. lol

You'll do fine in the end, I'm sure.

[irish44j]

yah....worst case the car won't start and I futz around with them a bit. I think I have them right now, we'll see.

Odd that as good as BMW was on the e30s at labeling things or putting numbers on things, they didn't think to number the coil wires or plugs............Teutonic fail.