So I bought a wrecked '99 M3...

[Gooch]

And obviously, I plan on doing an OBD-II S52 swap. The general idea is raceland headers, m50 exhaust, tune from TRM who will also delete the emissions stuff (rear o2 sensors, secondary air pump) and EWS.

I've been researching for what seems like months because I've been passively looking for an S52. This car basically dropped into my lap two weeks ago, so I jumped at the opportunity. Fast forward to this past weekend (which luckily was my fall break) where I ripped out the engine and trans and stripped the car.

I took all the obvious items I'm going to need from the car, but I'm wondering if I'm missing anything. I took the entire engine wiring harness and plan on making an adapter to hook up to my c101. Do I need any of the body wiring? What about the three connectors in the engine bay and the associated wiring? I snapped a quick picture, but it's pretty much mayhem:



The fuse box was all smashed from the accident so I wasn't sure how to take it all apart. Some of the connectors in that bunch plugged into the A/C compressor and the (I think) secondary air pump. Do I need these?

What about the fuel pressure regulator/purge valve/contraption on the drivers side frame rail? It has what seems to be a vacuum line going to the intake?

I am under the impression an e36 diff has different mounting points and simply swapping the cover does not work. Is this correct? I plan on using the ZF that came with the M3, so I'm looking for a 3.25 or similar ratio LSD, I presume.

I think that's all for now, any help is appreciated. Build thread will come in May when I'm home from school, although I'll probably start resealing the engine and whatnot over my winter break.

[Dissembler]

You're going to need:

-Driveshaft
-Shifter Assembly
-Body Side of X20 (for your adaptor)
-The 3/2 way valve (aka fuel pressure regulator) from the frame rail.

There isn't anything else you'll need from the donor car for your swap. A/C is all taken care of by the E30 wiring. Just adapt the clutch control terminals to the E36 compressor

Suggestions:

Since matt is flashing out ews, buy a different ecu for him to flash. Pull the ignition barrel, antenna, transponder, ecu, ews II module and all the door locks/trunk locks and sell them on ebay for $500. Matched sets can be worth a lot.

[Gooch]

Wow, thank you. I didn't realize all the EWS stuff was worth that much cash. I'm assuming the driveshaft needs to be shortened for use with an e30 compatible diff? I have the entire shifter assembly, so I'm good on that.

Thanks for clearing things up for me, I really appreciate it. Looks like I'll have to look up where people are mounting the FPR from the frame rail onto the e30 when they do OBD2 swaps.

[Dissembler]

The drive shaft is the perfect length. You'll want to buy a new CSB because the E30 CSB is needed to hold the driveshaft up in the middle (E36 won't bolt up). The drive shaft length is adjustable +/- 2" to suit your specific installation.

I mounted my FPR on the firewall, almost exactly behind the throttle pedal. I'll see if I can snap a pic of it tomorrow. There is also a stud on the framerail that can be used, just behind the charcoal canister

[Gooch]

Awesome, thank you so much for the help.

A picture would be amazing. I have an M42 so I don't have a charcoal canister, I wonder if I still have the stud...

[cabin]

FWIW, M42s do have a charcoal canister. At leats mine did...

[ColdAccord]

why obdII? obdI is such a better idea...

[Gooch]

I have not noticed a charcoal canister on my car, either I'm blind or the PO got rid of it. Either is a good possibility.

And why swap to OBD2? First off, I like the diagnostic properties of OBD2. Second, I have the entire car, so why would I want to convert to OBD1 when the only gain is an M50 intake? I'm going to swap to an M50 intake anyway, so why spend the the plethora of extra money to delete all the OBD2 stuff and buy all the OBD1 stuff when the only gain is the intake??

Not to be an ass, but am I missing something in the "convert to OBD1" bandwagon?

[325issguy]

My 318 also had a charcoal canister.

Obd1 is just a much simpler swap with alot more information in case something goes wrong.

[Gooch]

Just scored a spare X20 at the junkyard today. There was one e36 M50 car with no intake, no e34 M50 cars, and one ix with no brake booster. Talk about your all time backfires.

Anything else I'm overlooking, guys?

[IanS_in_Oz]

If you have all the OBD II parts already (as I did), I can see no valid reason to front up with extra $$ to change to OBD I.

I hooked up the EWS and all to my E30, works just fine.

[Gooch]

Thanks, Ian. Anything else you can see that I'm overlooking?

If I do an M50 manifold do I still need the fuel pressure regulator on the frame rail?

[jrdeamicis]

I fully support your idea of the OBD2 S52 E30. Whether you swap to OBD1 or stay OBD2 I just recommend putting down the cash and replacing some of the critical sensors.

I just retrofitted my S50 to accept OBD2. Love the diagnostic parts of OBD2 and some of the emissions control.

[Gooch]

I will ohm out the sensors to see if they are within spec, but I do not plan on replacing them if they don't require it. The motor only has 95k according to the PO.

I am very excited to start the swap and I plan on creating a thorough thread because there does not seem to be a DEFINITIVE detailed thread pertaining to OBD2 swapped e30s.

[jrdeamicis]

What I can see being the pain is the 4 O2 sensors and the O2 pump. But neither of those are hard. You will have to take the FPR from the body of the E36 and mount it on your car. And that will tie into the engine harness. Running losses Im not sure how you would deal but its part of the harness also.

Reverse lights are integrated into the engine harness. So you can leave them unhooked.

Coolant temp you will have to figure out, since the OBD2 head uses a single 4 pole sensor. People drill and tap the head for the E30 sensor thread.

As far as not replacing sensors. My cam sensor with 75k miles had all the insulation on the wires completely cooked shorting out the sensor. Pull back all the strain relief and check that out at the same time.