The comprehensive DOHC engine swap thread.

[Mike B.]

Engine side and chassis side wiring colors will differ, this is typical.

The best way to trace wiring is using the Bentley and ETM (electronic troubleshooting manual) for the year of your vehicle. Scour the ETM for everything related to the C101 connector and you will have your chassis side of your diagram done in no time at all. Now do the same for the E36 engine side.

Don't rely on diagrams you find on the net. Use them as a reference, but don't forget to do your homework.

[asubimmer]

yeah I looked at most of the wiring diagrams ppl posted up and spent about 6hrs going over all my wiring stuff for my car and crossing everything to make sure it was right. And all that time spent payed off b/c I didn't have anythign wired in incorrectly.

[Brew]

Now that the OBD2 dme has been 'cracked', its no longer a performance gain doing the OBD1 conversion. And the diagnostic capabilities of OBD2 make it well worth keeping it. S52 + OBD1 intake manifold + 24#/euro hfm kit is the way to go for sure.

[etxxz]

^^ refering to the whole tunning & chipping...amen to that

anyone know where i can get the pin chart for an S52 to make my own C101 adapter? ('97 s52 & '87 325is)...cant find it here:

http://wedophones.com/BMWManualsLead.htm

although i'll guide myself by what's been posted, i want to make sure its right the FIRST time
(this specifig post# is what what i norrowed my situation down to exc. its an s50)

http://www.r3vlimited.com/board/showpost.php?p=542611&postcount=38

[Mike B.]

There are no pin charts for C101 in the ETM's. You have to go through the individual systems one by one. Scan each page for the '97 and '87, and write down wire colors and functions when ever you see a designation for x20 on the '97 or c101 for the '87. Now start matching functions. This will give you everything you need to wire up the car properly and have it start on the first try.

That's my wiring diagrams and it's for an M50 and a late model '89. There are some significant differences between the '89 and the '87. For example the ABS is wired completely different in the '87 compared to the '89.

[etxxz]

i will do that, sounds like the only way to go thanks!

[Farbin Kaiber]

Now that the OBD2 dme has been 'cracked', its no longer a performance gain doing the OBD1 conversion. And the diagnostic capabilities of OBD2 make it well worth keeping it. S52 + OBD1 intake manifold + 24#/euro hfm kit is the way to go for sure.

Does that mean I dont need ecm, ring and key from a 96+ e36 anymore? I had not heard this, can you elaborate? Ill use my other stuff (obd1 manifold, oil pan), but who has done the "cracking", and what ecm does one need to find? sounds an easier route now.

[Mr.SWISS]

Does that mean I dont need ecm, ring and key from a 96+ e36 anymore? I had not heard this, can you elaborate? Ill use my other stuff (obd1 manifold, oil pan), but who has done the "cracking", and what ecm does one need to find? sounds an easier route now.

They sell an EWS delete chip at several places notably Turner Motorsport.

[gregslow318i]

I was already planing on doing a the obd 2 to 1 conversation. my question is this how do I adapted the obd 1 motor harness to the 85 318i body harness as my car does not have a c101 plug like the later cars do.
has this ever been done to a early car or should I start looking or another shell?
thanks

[E30 Memorial]

They sell an EWS delete chip at several places notably Turner Motorsport.

I can only find EWS delete for OBD1. Am I just not finding it or is there still no way to disable to EWS on OBD2 systems?

[e30polak]

just look at their application chart under obdII software

[MIKe30]

You dont have too its just better for performance.
The OBDII set up is more constrictive with the air intake and the emmisions i beleive. Converting the engine back to OBDI yeilds more HP in the end yet i am under the impression that is still keeps the small torque gain that OBDII had over OBDI with the engine being bigger.
Altho i could be worng on this theroy, some one slap me if i am miss informed.

has anybody confirmed exactly how much of a gain is associated with the obd1 conversion (hopefully with dyno numbers/charts)??


it must be a significant gain (i think i remember reading 30 or so hp? i'm thinking thats to the crank?) because i've done some reading and i cant seem to come across anything else that suggests why the US s52 is better than a US s50.

any insight or a point in the direction to the right answers would be great. thanks :)

[etxxz]

^^ i'll say it again. you DO NOT NEED TO CONVERT TO OBDI to have an M50 manifold which is only important hardware piece that is changed and probably the only reason for hp gain. Software tunning/chip is available, maybe a tad more expensive [not really] but probably yields better gains due to larger displacement. check my post on pg59....then again all of this minus what i say about the m50 mani is speculation

[MIKe30]

^^ i'll say it again. you DO NOT NEED TO CONVERT TO OBDI to have an M50 manifold which is only important hardware piece that is changed and probably the only reason for hp gain. Software tunning/chip is available, maybe a tad more expensive [not really] but probably yields better gains due to larger displacement. check my post on pg59....then again all of this minus what i say about the m50 mani is speculation

i read what you said before i posted the first time. i ask because the car i just picked up already has an s52 with full obd1 conversion. so if you happen to have the answer, (and not in arrogant caps assuming i havent read or tried to search for anything at all) then i would be happy if you or anyone else could share their knowledge. thanks.

[etxxz]

i didnt mean to be arrogant. just becuase there's so many posts people will skip over info. caps = in your face kind of a post.

KO performance claims 32whp on a boosted s52. i know someone who works/adds for them and i trust when he says they did it w/o altering any boost or a/f settings. NA idk, i've read from 10 up to 25 on bimmerforums but don't quote me.