Getting supercharged obd-II s52 engine...questions...

[JGood]

I bought a 93 325is at Copart (wrecked auto auction) and am parting it out, and actually am making an unreasonable amount of money because people are begging for stock e36 parts it seems. Anywho, while searching for a wrecked m3 for my next auction purchase, to use the engine out of, I came across a rear hit 74k mile 96 m3 that upon closer inspection has a supercharger bolted on, as well as a roll cage and five point harnesses on the inside. So I'll prolly pick this up for 2-3k and part it out, make my money back and keep the engine/supercharger for free.

Can I keep it OBD-II for the e30 swap or does it have to be converted to OBD-I? The reason I think it may be a hassle to convert is the supercharger setup, and even if it would be easy, that's an extra 30hp or whatever I don't need because traction will be an issue as is. And being 20 years old I don't want more then 280 whp or whatever it is in a 2700 lbs car, that just has trouble written all over it.

Does the DME plug into my existing computer connecter? Anyone know the wiring match ups for an 85 325e to a 96 s52? Should I keep the tans out of my current parted out 93 325i to use with 178k miles, or anything else? Anmyone have any sources for 5 series oil pans?

[niq_nak]

not completely sure, but i think i remember my friend with an s52 e30 saying that they had to convert it back to obd-i because the obd-ii wont start without the original key or something like that. im sure someone else who knows more definately will chime in.

[Ryan Stewart]

Umm. No, no, and no.

You will need to convert or figure out who to make the DME think that all the sensors and secondary air systems are still hooked up. Its much easier to just put the OBD1 parts on there.

IF you are worried about safety and traction buy a 84 318 and keep good tires on it. If youd rather have fun put the s50 into the E30, supercharger or not. People have been putting down 300whp into E30s all over the world, dont drive stupidly and you will be fine.

wont plug in, you have to modify the wiring.

[JGood]

Well I know there is some wiring involved, such as the engine harness to the car's harness, but as far as the actual ECU, does that plug into the large white connector or do I have to redo all the wiring under the dash to match the engine stuff? If so, wouldn't it be easier to run all new wires?

What all is involved in converting to obd-I, and how much am I looking at spending? Maybe I'll just trade this supercharged s52 for a s50 plus some $$$. I don't need that much power, it's a daily driver I don't want to break it.

I could maybe get 6k for this, and buy a s50 for like 3k, and have some money left over for some brakes and tires. What do you think. But DAMN, will I ever regret that within 6 months.

[Bryson]

for the wiring

SERIOUSLY. Read the ginormous thread that we have written about the 24v swap
If you cannot answer your own questions after reading that, it is highly unlikely that you are capable of such a swap

[JGood]

I have read the thread. I also check it on a daily basis for new posts. I took all of the information and sectioned it and put into into a Word document for my own use when I do the swap. Mechanically, I know the swap inside and out. NOBODY has given even remotely a complete writeup on wiring. But being fairly good with electrnoics I'm not worried. I just have a few questions.

Does my 85 325e have a engine harness plug or not? Because some people have told me it is straight wired into the car, which actually makes the swap easier because there is very few wires.

Nobody has mentioned plugging in the computer module, as far as the actual harness plug that goes into the computer. Does the stock one work or do I need to splice in a e36 one in the gloveox?

Two fairly simple questions, that to me were not clear in the 38 page thread, I don't see a problem.

Also, I have never seen a writeup on the obd-II swap, so I would like to know what all is involved.

Thanks,

Justin


------
85 325e
5 speed swap
Sachs Sport Clutch
Z4 shifter
H&R's/Bilsteins
Mille Miglia MM11-2's
BMP body kit
Autothority chip
Borla Exhaust
.....and much more

[Bryson]

well, first of all: the DME connects only to the motor's wiring harness, there is no splicing to get that to work, thus you need a 24v computer. 24v motors don't work at all the same as the 12v, using TPS, MAF/HFM, and some w/ VaNoS and knock sensors

every e30 AFAIK has an engine harness plug. Wiring is easier on an 88+ car. That is my personal opinion having done both cars multiple times. The wiring is likely not included here for legal reasons, as it comes mainly from companies who have marketed their info (cough: zoinsville). You must ask someone who has done the swap how they did their wiring. It's a fairly simple, logical task.
On a late e30, you have to splice in only ONE place, there the engine harness connects to the car harness. Now if you go through the 24v swap info again knowing this, it should be glaringly obvious

edit: there is no write-up on the obd-2 swap because there is no viable, justifiable reasoning to do it. And it's far beyond the capabilities that you and most others have portrayed to have in this thread

I'm done talking, any more questions can be answered by anyone else

[JGood]

Well you answered my question by mistake I think. I thought there was a car harness in between the engine and ecu, and you spliced the engine harness to the car harness then the car harness to the new ECU. So the engine harness will include a plug for the ecu for under the dash? Then why is there any wiring at all? Just for various sensors?

I meant an obd-II to obd-I swap, not an obd-II s52 swap. I know that would be retarded, less hp and more hassle. I need to know how to convert an obd-II engine to OBD-I.

[BahnE30]

here maybe this will help

Harness A = S52 DME Harness
Harness A1 = S52 DME in Glove Box

Harness B = S52 Engine Harness
Harness B1 = E30 Chassis Harness

Connect A to A1 and B to B1
don't ask me how but thats my take on this topic.

[Brew]

Well you answered my question by mistake I think. I thought there was a car harness in between the engine and ecu, and you spliced the engine harness to the car harness then the car harness to the new ECU. So the engine harness will include a plug for the ecu for under the dash? Then why is there any wiring at all? Just for various sensors?

I meant an obd-II to obd-I swap, not an obd-II s52 swap. I know that would be retarded, less hp and more hassle. I need to know how to convert an obd-II engine to OBD-I.

I can't help you with the OBD-1 conversion, but check over on bimmerforums. Obviously its not something that us e30 folks have to deal with often.

I think you've got the right idea about the wiring. The only wiring interface between the M/S50 and the e30 is at the main plug, which is directly to the right of the fuse box, and power/ground. The engine harness has a plug for the ecu, and it is long enough so you can put it in the glovebox.
The interface between the motor and the e30 chassis is for a few different things- instruments, check engine light, fuel pump, etc. Start with the pin chart on www.akgmotorsport.com and check the DOHC thread on this forum for any further questions. The wiring is definitely one of the simpler parts of the swap.