87e to 91is swap

[nu-B]

I have been looking around and really haven't found much reliable info about doing this swap. since you read the title you know i'm working with an 1987 325e chassie and just picked up a 1991 325is motor. It came with for what i know to be all sensors including mas.Have ecm, full harness including the fuse box. On the underside of the fuse box the wires are cut with enough to splice in if needed. The only parts I didn't get were the oil cooler and lines, and radiator.
So being that I have done some research and know that the trans's are slightly different. One has your crank sensor the other does not. Does this trans have any other un-similaritys? The "e" trans will bolt up and use same starter rite?
I wouldn't think this swap would be very hard being that this motor came in this car just different model. I've done a sr 240 before and the wiring on that was not that hard did it in about 4 hours.

So I guess I'm wondering if anyone that knows something would like to lend some advise this way it would be much appreciated.

[nu-B]

All I'm looking for is the 20 pin connector differences and what to do about it. The "E" has 11 pins being used and the "IS" has 17. What do I do to use a pig tail or spice??????????????????????


Please help I have 25 days left untill I drive this car from CO to IL.

[Adrian_Visser]

I would do the same thing as you would for a 24v swap. Go through the electrical troubleshooting manuals for both years at http://www.wedophones.com/BMWManualsLead.htm Start at the power distribution section and write down the pin number and wire color of every instance of the c101 connector.

Not sure what I mean by that? read this: http://www.r3vlimited.com/board/showthread.php?t=147862

Then either splice the old square connector off the old harness directly onto the new harness in place of the round c101.

Or:

Get the bodyside round c101 connector off a junkyard car and make a harness adapter with the old square plug. Leave a fair bit of wire on both connectors and just splice the wires together.

You will have a couple extra connections that go through the c104 on the older chassis that on the late models were integrated into the c101. IIRC they are the tach, road speed signal and something else which escapes me right now. How you connect those wires to the c104 will depend on how you adapt your c101.

[nu-B]

Thank you Sir.. I'll look into the link you posted.

[MR 325]

Use an 87 325i/is engine harness. It will be plug and play.

[nu-B]

well I talked to a shop to day that told me its just plug and play anyway. He said as long as I had the full engine harness with relays it will just run. The only thing i don't want is to do this and have it fry my computer.

[MR 325]

If you say so, not like I've done this before...

[nu-B]

im not saying you haven't mr325. But the owner at Auto sport werks in Broomfield CO said all I need is the complete engine harness and computer and it would work in dam near any older bmw. He seemed more than confident and said he's been doing these swaps for 20 plus years.

[nu-B]

Well if you have a spare I'll buy it. But finding a new one is about 700 if its available. Junk yards around me are usully picked clean. I'm not interested in buying another parts car just for the harness. So now what? Why is it such a big deal to make the 91 harness work with the 87? P.S. I'm not looking to piss you off I just need a solution for this because I have 22 days before my 1000 mile drive. I like making friends not enemys.

[nando]

im not saying you haven't mr325. But the owner at Auto sport werks in Broomfield CO said all I need is the complete engine harness and computer and it would work in dam near any older bmw. He seemed more than confident and said he's been doing these swaps for 20 plus years.

too bad he's wrong.

do what the other guy said - make an adapter. the M50 guys do it all the time, it's no different for an M20 swap.

[lateracer]

I dropped an engine harness from an 89i into my 87e with no cutting or splicing. I asked the same question about the old vs new C101 connections.

I didn't really get a definitive answer, so I wound up crossing my fingers and just plugging it in after some probing with a volt meter to make sure I wasn't connecting a powered line to a grounded one. I plugged it in without a DME connected first, then with it. It worked fine for me, but there are stories of people frying harnesses.

If I had to do it again, I would connect an ammeter to the main power cable to watch for a spike when everything was connected. Good luck.

[nando]

he has a 91 harness though. There are differences from 87-89-91. There's a risk of melting wires, or doing some quick research and modifying the harness to work. And it's definitely not true that any harness will work in any old BMW. The older ones don't have the same connector.

[Sharino]

I got a 87i harness complete if interested, shoot me a pm

[nu-B]

Ok I found there are 3 differences. 1st The E number 15 is RXD/ diagnosis sensing lead. On the "I" it's EGS control unit.
2nd pin number 19 on the "E" is Timing control/ distributor and on the "I" it's Ground.

3rd pin 20 on the "E" Motronic control and on the "I" it's EGS control unit.
Does any of this make sense to any of you guys/and or gals????