M20 engine swap into 320i

[lasvegascop]

Ok...yes..i know...this thread is couple yrs old buttttt.....it does have tons of great info but unfortunately some of the links are dead....If anyone out there has updated info on the wiring and color coding to splice the E30 to E21 harness it would be so helpful....

Thank you upfront....

[todor]

My server is down again... since last week. But I'll fix it tonight when I get home. Sorry about that. When I do, the main link in the first post will be active, and there's a table in there about how to splice the harnesses.

[Tom D]

here's the ETM for the E30 325. the ETM for the E21 is in the FAQ at the top of the page.

http://wedophones.com/Manuals/BMW/19...g%20Manual.pdf

[Jester323]

I've got some helpfull information on our local forum: http://www.pnwbb.com/pnwbb2/index.ph...topic=876&st=0 Since I was unfamiliar with e30's when I made the conversion in my car & I didn't pull the motor, I have documented a few things that other writeups have skipped over assuming that certain wiring is obvious if you have pulled the 2.5L from an e30 yourself.

Below are some exerpts from my writeup there regarding wiring:




I cut off the relay sockets (closer to the relay sockets than to the fuse box connector) from an e21 engine wiring harness, and cut the other end of the engine harness just before the next pigtail that came out of it, giving me a 28" long pigtail with the fuse box connector.

Once this is done, there are five shorter wires coming out of the plug. Three of these are just not going to be used (at least on my connector & sounds like John's has the same wire colors) and so I left about 6" of the wire and put some heat shrink on the end so that I could safely tuck them inside the conduit. The wires that will not be used are:
E21 fuse plug pin # : wire color
6 : green/violet stripe
8 : solid green (there are two, only one is needed)
10: black (there are two, only one is needed)

I then deviated from the other's wiring diagrams to something that seemed to make more sense to me. I took the black/yellow stripe wire that I had clipped from one of the relay sockets and soldered/heat shrinked it to the small black wire coming from pin # 15, and I have found that this is the tachometer signal lead. It connects to pin # 1 on the back of my 6-cyl 323i tach (middle post of the three-pin connector on the back of the gauge cluster). You will notice that Todor's wiring diagram & others indicate that this color wire should be for the starter trigger wire, however there are already two full length solid black wires from pin #10 so why swap colors. Typo from Todor? I tested the leads from pin # 10 with an alligator clip to the post on the top of the starter, this was the only pin that would actually engage the solenoid with the ignition in the on position and the start button pressed. I fried a $6 Harbor Freight DMM trying to figure all of this out... luckily I had an old analog MM on hand as a backup.

Okay, so there is also a green wire with black stripe going in & out of one of the relay sockets. This connects to pin # 3 for the fuel pump relay. I soldered/heat shrinked these together as well.

Then I took all of the excess wires that I didn't need and pulled them free from the conduit & tucked them away in my scrap wire pile. Then I tucked the three dead ended wires into the conduit & slid it up to cover them & added a 3" length of 3/4" diameter heat shrink (of course from Harbor Freight, hey, they had a pack of 5 different sizes on sale for $7!) and snugged up the end. I then slid an 8" length of 3/4" heat shrink over the other end to prep for the connection to the e30 screw-on plug (which I don't yet have in hand, and no, I probably won't cut this out of Susan's brother's car)














The extra wire is for the "check engine light"

[lasvegascop]

OMG!! Thats beautiful !!!!!!! wow.....

Thank you so much for me and for future swappers......PERFECT!

[Jester323]

note: my harness is probably at least 6" longer than it needs to be.

[lasvegascop]

SO it should be around 22 to 24" long?

[Jester323]

I'll measure it as soon as I get a chance.

[nMide]

To add to this:

By modifying the subframe and mounts slightly a friend of mine was able to make an M20B25 fit into my E21 with the stock E30 engine brackets...the engine seems to sit slightly farther forward than it would have with the 323i brackets.

[lasvegascop]

I'll measure it as soon as I get a chance.

Any word on the lenght? Im just about to get started on the wiring?

[jjgbmw323]

note: my harness is probably at least 6" longer than it needs to be.

So I am confused, i thought you modified the e30 harness to fit the e21 323i fuse box....

[Jester323]

SO it should be around 22 to 24" long?

yeah, go with 24" to be safe.

So I am confused, i thought you modified the e30 harness to fit the e21 323i fuse box....

I did. The e21's engine wiring harness has a plug into the fusebox, I just spliced this into the e30 engine harness as shown in the pics above. All I was trying to say was that there is more than enough harness length with the e30 harness, and that mine has a bit of excess slack in it. So when you splice the e21 fuse box plug into the e30 harness, the overall length between connectors should be around 24", not 28".

I spent some time the other day to fix a problem that arose last summer, my original e21 323i throttle cable snapped due to excessive angle at the mounting bracket on the intake manifold which caused an odd wear pattern. So I set about to see if I could use the e30 throttle cable and brackets in an un-modified way. Once switching to the the M20b25, the engine side really does function better if you can use it, the pedal side of the cable is something that I just "made work" for now.

The first real issue is how to adapt the e30 "hook" end of the cable instead of the e21's "loop" end style cable connection. What I came up with is not a permanent solution, the right thing to do is to remove the pedal assembly, drill a hole and use a bushing like the e30's do. When this zip tie breaks, I might think about it... or maybe the second or third time...

I really think that this is actually a better solution than trying to make the e21 cable work.



Once this easy enough solution was determined, I now needed to check out the length and fit it up. As it turns out, the e30 cable is actually an inch or two longer than the 323i e21 cable. So I needed a spacer for the end. I came up with a super simple spacer using an electrical butt crimp connector, cut off the excess plastic on one end, kept the steel sleeve in the middle, and presto, throttle cable solved.







regarding some of the wiring that nobody else seems to talk about, and is really a no-brainer if you pulled the m20 from the e330 your self, but if you have never seen an m20 hooked up in an e30, then you will probably wonder where this stuff connects to:





I knew that the wires with the red arrow go to the coil. I needed to extend these in order to mount the coil in front of the washer fluid reservoir. One of these is a shielded wire.

The wires with the blue arrow go to ground. A self-tapping sheet metal screw into cowl took care of that.

the connector with the green arrow goes to the O2 sensor.

the wire with the yellow arrow goes to unswitched battery power. I also extended this pigtail to connect to the main terminal on the starter. I might eventually redo some of this and use an e30 unswitched power bus and mount it on the firewall just like the e30.

I converted mine to use a MAF rather than the OEM "barn door" AFM. This is how I plumbed it. I just used some silicone couplers, the MAF from Miller Performance, and a bracket that I built.

[lasvegascop]

Did you notice any difference switching to MAF rather using OEM setup? Just wondering

[Jester323]

I never ran the 2.5L in mine with the AFM, so I can not give you a first hand account of the difference.

However, ask the guys in the E30 section, R3V, e30tech, etc & you'll probably get 80-90% that will tell you the but dyno is in strong favor of the MAF over the AFM. I have not seen any actual Dyno data, but I would love to.

The fact of the matter is that the AFM uses moving parts, and is a grossly inefficient way to meter air, so the logical upgrade is MAF. A "chip" is almost everyone's first upgrade to an EFI system. The Miller system needs a chip in order to run the system on the different voltage with the MAF than the AFM anyway, so might as well rewrite the maps on the performance side while your at it right? Another common upgrade for the m20b25 is to switch to 4-pintail, 19# injectors. Miller has a chip that utilizes the added fuel capabilities of the larger injectors and the MAF signal at no additional charge.

Let's just say that mine is currently the quickest e21 I've ever driven, by a decent margin. I've driven quite a few. The closest would probably have to be Jeff's (Alaskabimmer) 2.7L Kjet powered Baur.

[jjgbmw323]

I never ran the 2.5L in mine with the AFM, so I can not give you a first hand account of the difference.

However, ask the guys in the E30 section, R3V, e30tech, etc & you'll probably get 80-90% that will tell you the but dyno is in strong favor of the MAF over the AFM. I have not seen any actual Dyno data, but I would love to.

The fact of the matter is that the AFM uses moving parts, and is a grossly inefficient way to meter air, so the logical upgrade is MAF. A "chip" is almost everyone's first upgrade to an EFI system. The Miller system needs a chip in order to run the system on the different voltage with the MAF than the AFM anyway, so might as well rewrite the maps on the performance side while your at it right? Another common upgrade for the m20b25 is to switch to 4-pintail, 19# injectors. Miller has a chip that utilizes the added fuel capabilities of the larger injectors and the MAF signal at no additional charge.

Let's just say that mine is currently the quickest e21 I've ever driven, by a decent margin. I've driven quite a few. The closest would probably have to be Jeff's (Alaskabimmer) 2.7L Kjet powered Baur.

Yes, nice pic I am going with the Miller War chip and 3.0 Maf with 19lb injectors, and if you drive mine you will notice that its a 2.9/3.0liter m20!

[murran]

id like to know the difference in power/drivability with the maf conversion.

[Jester323]

So third party reports are all over the board, mostly because there are so many different varying degrees of modified m20s slapping a MAF conversion on and then reporting butt-dyno or actual dyno runs.

The general consensus is that the Miller chip (needed for the MAF) is as good if not marginally better than the leading Conforti chip. However, the MAF isn't just about peak power gains. In fact, the real story is how much sooner and longer peak power is availible and will allow better throttle resposnse by not having to push the door on the AFM. If you plan on doing much more than the 19# injectors, K&N & exhaust, then you should really be looking at the WAR chip instead of the pre-programmed chip that comes with the MAF kit.

This is taken from Miller's site:


What are the gains I can expect from the MAF System?

The MAF System replaces the stock AFM. We guarantee at the VERY LEAST the same gains as the leading performance chip. However, on top of that we also guarantee a better mid range, a flatter torque curve and drastically improved throttle response. Unlike the AFM, there is no "door" restricting flow. Due to no obstructions during part throttle you are able to flow more air into your engine. The chip provided with the System allows for your ECU to run the car as if the MAF sensor was an original BMW component. As far as recorded power gains go, you can expect 10 - 20 HP and 15 - 25 Ft. Lbs of torque depending on which engine you have. Here (bottom of page) are some Dyno sheets for the e30 325 and the e34 535


I will leave it at that. We can discuss MAF more in another thread if you would like.

[EBMW21]

^ i love having miller local to me (about an hour drive). when i do my m20 swap i was planning on taking it to them to the the pro street induction kit, maf and war chip. but have them tune it on there dyno.

[lasvegascop]

So how are the wrap on your headers is working out so far?? Noticed any temps drop

Let me know

[todor]

My web site is back up and running after being offline for a few months. I finally fixed my server. The link in my original post (and in my signature) works again. Happy swapping!

(also, I see some good info and pics added to this thread over the last few months - do you guys mind if I use your pics to update my write-up? I'll put up a source note in there )

[ThisGuy310]

My web site is back up and running after being offline for a few months. I finally fixed my server. The link in my original post (and in my signature) works again. Happy swapping!

(also, I see some good info and pics added to this thread over the last few months - do you guys mind if I use your pics to update my write-up? I'll put up a source note in there )

Thanks for getting your site back up!
I've been looking over it and it's a great source of info along with this thread.

I purchased a late model 323i subframe off a forum member on here, but I still need the metal support brackets as well as rubber engine mounts.

I just wanted to confirm that these are the correct part numbers I need before dropping the $ on them.

[kdonn]

I purchased a late model 323i subframe off a forum member on here, but I still need the metal support brackets as well as rubber engine mounts.

I just wanted to confirm that these are the correct part numbers I need before dropping the $ on them.

I've got some euro engine support brackets if you're interested. See my old post.

http://forums.bimmerforums.com/forum....php?t=1688311

There are two styles. I believe to older style are metal and the newer style are aluminum. I have both pictured in the thread.

[Jester323]

Check out the Eurometric mounts (part #2 above) before buying new rubber ones!

[ThisGuy310]

Did anyone ever figure out a good solution to getting a working speedometer when an e30 transmission such as the getrag 260 is used with the stock e21 diff?
Since the G260 has no hole for the mechanical speedo, and the e21 diff can not accept the e30 electronic sensor, what have people been doing?

I was wondering if something like this would work?
http://www.amazon.com/250-4165-Magne.../dp/B0009GVUG8
I would probably have to get an aftermarket speedometer gauge, but I am ok with that as my current gauge has never worked properly.

[lasvegascop]

That's a nice find and it sounds practicle and doable....

Thank god I don't have to mess or worry about that obstacle ......