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Motor Swap And Fi Conversion Questions


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Alright, so hang with me here. I'm really trying to get a grasp on everything and having a hard time figuring out what I am trying to figure out. I'm a mechanical newbie and my 02 is the first car I've ever worked on myself.

 

*As a disclaimer, all the plans I have (and that will be listed below) will have supervision and help from people who are more mechanically smart than I am.* (good grammar Jack. This post is a surefire winner)

 

My situation is this:

 

My stock 02 M10 is tired. It has leaky gaskets, the carb needs rebuilding, the transmission isn't super peppy, etc. I really want to do some sort of fuel injection set up. Being the impulsive dumby that I am, I recently went and picked up a recently rebuilt M10 out of a 1980 320i and a G245 out of an 82 320i. It did not come with the intake manifold, throttle body, or sensors necessary to set up the fuel injection. I didn't really understand fully what all was required in doing this swap. So now I'm left with a solid engine (I'm told it has about 5-10k miles on it since the rebuild) without any of the parts that would be necessary to run fuel injection, the ECU from the 1980 320i and a 5 speed.

 

*Let's all take a moment to observe Jack's stupidity. *

 

My confusion:

 

Everywhere I turn when looking for advice and guides for swapping in the E21 M10, I always find long build threads with complicated Megasquirt conversions with ITBs and blah blah blah. No one ever just swaps the motor in with the stock kjet fi. I understand that the kjet is not the best way to do it, but for the end result I'm looking for, I want something that is fairly simple, doesn't require TOO much maintenence and more importantly, doesn't require all the expensive aftermarket MS parts.

 

Now my question:

As the pre-requisite for this question, let's disregard all the steps necessary to install the 5 speed (I've sat down and chatted with a few people who have broken it down pretty well for me).

 

My simple mind seems to think that if I had a running e30 318i, or a running e21 320i or something like that, I would be able to pull out the ECU, the wiring harness (maybe have to get a new harness to make everything kosher with the 02), the intake with the throttle body, and everything else that goes into making a motor run, wire it up and then drop it into the 02 and everything should work just fine and dandy.

 

(everyone take a quick break... This post is getting wordsy)

 

 

Obviously I understand there will be some complications along the way. I get that. I will need some parts to make certain things work with the 02 (things like the driveshaft and the long speedo cable, etc in the case of the transmission). But if it was working fine in the E30 or the E21 it came out of, it should work just fine in the 02? No? Yes? Am I an idiot (well that's an obvious one... Don't answer that)? Basically everything that would be swapped in would be straight off a working parts car.

 

Sub-question to the original question:

 

Assuming I am able to find a parts car with everything mechanically sound. What parts are going to be necessary for me to make the engine compatible with the 02.

 

My solution:

 

You. You, are my solution.

 

 

I understand this is a pretty wordy question and I hope I didn't alienate anyone. Everyone always says that you gotta start somewhere and sometimes the best thing you can do is to do it yourself. But those people are stupid and never dealt with figuring out how fuel injection works. (that last part is a joke.)

 

If you are feeling especially kind, but your fingers don't want to type out your incredibly detailed and eloquent response, I would also be up for a phone call/cup of coffee/beer where you could explain all the things while I took notes. My phone number is 951-7one9-5five9nine and I live in the LA area, specifically in West Covina.

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Ok, I'll take a stab at this. I'd say the first thing you need to consider is which particular FI system you're going with and that will usually be down to cost and availability.

 

The e21 Bosch K-Jet is a mechanical FI system and therefore has very little wiring (some have lambda correction). The injectors differ from the modern type and so the inlet manifold is specific.  Folk tend to have a love/hate relationship with K-Jet, it does have advantages but can be difficult to set up.

 

E30 is usually L-Jet or some close variation and is a more modern system as it uses electronic control. L-Jet lends itself better to a Megasquirt conversion because it has most of the expensive aftermarket MS parts in place. With the exception of the MS ECU and optional wideband controller these parts cost the same whether doing a MS or L-Jet conversion.

 

Yes, both systems would work by transferring all the hardware over including fuel delivery flow/return, metering mechanism, throttle body, plenum, fuel injectors, temp senders, manifolds etc. and a bit of creative fabrication. For simplicity either of these system are fine but they control fuelling only whereas Megasquirt is a complete fuel and ignition engine management and the ability to map ignition will net you the most gains on a n/a engine.
Hope this helps
Rgrds

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Ok, I'll take a stab at this. I'd say the first thing you need to consider is which particular FI system you're going with and that will usually be down to cost and availability.

 

The e21 Bosch K-Jet is a mechanical FI system and therefore has very little wiring (some have lambda correction). The injectors differ from the modern type and so the inlet manifold is specific.  Folk tend to have a love/hate relationship with K-Jet, it does have advantages but can be difficult to set up.

 

E30 is usually L-Jet or some close variation and is a more modern system as it uses electronic control. L-Jet lends itself better to a Megasquirt conversion because it has most of the expensive aftermarket MS parts in place. With the exception of the MS ECU and optional wideband controller these parts cost the same whether doing a MS or L-Jet conversion.

 

Yes, both systems would work by transferring all the hardware over including fuel delivery flow/return, metering mechanism, throttle body, plenum, fuel injectors, temp senders, manifolds etc. and a bit of creative fabrication. For simplicity either of these system are fine but they control fuelling only whereas Megasquirt is a complete fuel and ignition engine management and the ability to map ignition will net you the most gains on a n/a engine.

Hope this helps

Rgrds

 

This helps a lot. The basis of my question outside of "would this work if I had a whole car to take parts from" comes down to what does creative fabrication entail? I am considering going and buying a cheap E21 320i or E30 318i and doing my swap this way. They seemingly can be had for very cheap (<$500 for running E21, ~$1200 for E30) but before I do, I want to know how much I need to be budgeting out for this fabrication.

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An E30 donor with healthy L-jet would be just about as plug-n-play as it gets. Budget for fuel lines, clips, filter, gaskets and maybe the odd silicon elbow, injector seals and a new fuel pump for the sake of reliability.
 

Stuff requiring creative fab: the fuel tank springs to mind as carb'd tanks don't have the return line, the throttle linkage will need adapting from rod to cable, various components will need mounting/brackets and the of course to loom will need figuring out.  Cost will depend on your skills, time & ability. It's a perfectly doable project, no doubt you'll hit a few snags but it's all been done before and nothing the knowledge base on here can't solve. Get stuck in it'll be a fun project

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ar_kid, I forgot to post a thank you reply but I really do appreciate your taking the time to write that up.

 

I ended up finding someone who is parting out an E30 318i who said I could come take whatever I wanted. I'm trying to build a list of the things I would need to be sure I don't forget anything when I go to pull everything out.

 

So far the things I've figured out:

Engine and tranny (duh)

Intake manifold with throttle body

Exhaust manifold

ECU and harness

The various engine sensors (what specifically would these be called so I can know what they look like?)

Fuel sending unit

Injectors (which if I'm not mistaken are located inside the intake manifold, correct?)

Distributor

 

What am I missing?

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You can use the l-jet efi on your E21 engine- in the days before MegaGooGoosquizzle, it was pretty common.

And it's still a developed, hardened EFI that you can find parts for. 

 

So subtract engine and transmission, since you have those.

Add the water neck from the engine, since it has a temp sensor you need.

The engine wiring harness, with enough body harness to adapt it to your car.

Take all E30 sensors- you'll find you don't need most of them.

You don't need the E30 exhaust- in fact, it probably won't fit.

You will want to weld a bung into yours for the oxygen sensor.

You need the AFM (flapper box with the air filter) and the idle motor. 

And the idle computer, a small green box inside the car, near the ECU.

 

Take the sender from the tank, along with the prepump.  It's fiddly- you remove

the inner sender (some nuts) first, pull it out, then weasel the pre- pump out.

You can then mount a high- pressure pump from a late E30 in your tank with this bracket

(and a bunch of fabrication) or you can get a '91 318 sender assembly and get

everything you need in one go.

It screws into the top of the tank.

Don't forget the ignition module- I think it's separate on the E30 (it is on the E21, anyway) and

all the wiring for it.  It should be part of the engine harness.

 

http://www.wedophones.com/BMWManualsLead.htm

and download the ETK for your E30-

this will be your bible, really.

From it, you can figure out what the EFI wants to keep it running,

which sensors you need, which are extra, and so on.

You'll need high pressure plumbing and some creativity, but it's not

a terribly hard conversion.

And when you get it done, you get to troubleshoot it like an early E30.

Which isn't that bad, really...

 

t

Edited by TobyB
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If you take the distributor from an E30, do not forget the control unit (on the drivers side firewall) and harness that go beween them. Without it the distributor will be worthless.

 

There is a writeup in the 'Articles/Engine and Drivetrain' section on the EFI conversion. It lost all of it's photos, but the words are still there. You might find more info in there to your lingering questions.

Edited by Mike87
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You can use the l-jet efi on your E21 engine- in the days before MegaGooGoosquizzle, it was pretty common.

And it's still a developed, hardened EFI that you can find parts for. 

 

So subtract engine and transmission, since you have those.

Add the water neck from the engine, since it has a temp sensor you need.

The engine wiring harness, with enough body harness to adapt it to your car.

Take all E30 sensors- you'll find you don't need most of them.

You don't need the E30 exhaust- in fact, it probably won't fit.

You will want to weld a bung into yours for the oxygen sensor.

You need the AFM (flapper box with the air filter) and the idle motor. 

And the idle computer, a small green box inside the car, near the ECU.

 

Take the sender from the tank, along with the prepump.  It's fiddly- you remove

the inner sender (some nuts) first, pull it out, then weasel the pre- pump out.

You can then mount a high- pressure pump from a late E30 in your tank with this bracket

(and a bunch of fabrication) or you can get a '91 318 sender assembly and get

everything you need in one go.

It screws into the top of the tank.

Don't forget the ignition module- I think it's separate on the E30 (it is on the E21, anyway) and

all the wiring for it.  It should be part of the engine harness.

 

http://www.wedophones.com/BMWManualsLead.htm

and download the ETK for your E30-

this will be your bible, really.

From it, you can figure out what the EFI wants to keep it running,

which sensors you need, which are extra, and so on.

You'll need high pressure plumbing and some creativity, but it's not

a terribly hard conversion.

And when you get it done, you get to troubleshoot it like an early E30.

Which isn't that bad, really...

 

t

 

 

Woah I somehow missed this one. This is awesome Toby! Thank you so much. The engine he has was rebuilt by a reputable shop down in San Diego and then never reinstalled into the car. I figure its worth picking up even if I end up choosing to just use the E21 motor. Either way I'll end up with a freshly rebuilt M10 installed and one I can sell on Craiglist. I was going to buy just the engine without the transmission but he said he wanted it gone so he threw it on top of everything for an extra 25 bucks. I'm getting all this stuff for only $875 so its not a bad deal for me.

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Wow, you can't buy a new set of pistons for much less than that- you'll be able to make a running car out of it, for sure.

 

And 'shakes is right- in 1980, the drive gear for the distributor changed direction.  So a 2l dizzy and a 1.8l dizzy (approximately)

won't swap.  So get the E30 dizzy, certainly.  And the head, if it's on offer...  but you can always get a 'reverse rotation' cam later, if

you really need it.

 

t

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