M30 swap question

[Spinning Tires]

Anyone ever try using the m20 computer instead? reason being my donar car was an e28 and has an older fuel injection setup wich means i will no longer have a working check engine light. if not then what m30 computer is a direct plug in for my m20 harness?

[bmw335isturbo]

Anyone ever try using the m20 computer instead? reason being my donar car was an e28 and has an older fuel injection setup wich means i will no longer have a working check engine light. if not then what m30 computer is a direct plug in for my m20 harness?

One computer that I know will work is the e34m30 should plug right in
but that is all that I know of this.

[Spinning Tires]

Thanks for the info. I think im gonna go with the m20 computer first and see where that gets me. If I have problems then i'll go for the m30 one

[SpunkyE30nOk]

www.jaredsquires.com awesome site to check out...from what i gather you can use the m20 wireharness/ecu if u are running an older m30...thats what i plan on doin since my m30 is from a e23 735i w motronic

[george graves]

I'm running a m20 harness (off a '89 is) connected to a m30 ECU (88' e24?)

[euroshark]

The M20 computer won't run right, but the M30 computer will plug right into the M20 harness!

[Spinning Tires]

Well i was looking up the wiring diagrams on Alldata and it seems that none of the pins are in the same spot for the computer. so i would either have to use the m30 harness i have or use the m20 harness and a newer comuter i guess. i dont see how the m30 computer would have worked on the m20 harness unless they changed the m20 from 1989 to 1990. not to mention the m30 im using has those 2 stupid sensors in the bell housing to tell crank position and load and my m20 has a normal crank sensor on the front instead. so it seems im pretty much stuck with getting a newer m30 computer

[euroshark]

Yep, M30 with Motronic 1.3 ECU, or just swap the harness.

It takes like 5 minutes with the engine out of the car, and as long as you are using a new enough harness (round plug), you won't have to splice much to make it work. I mated a 1980 L-Jet harness to my E30's stock fusebox and it took all of 15 minutes with the pinouts.

[Spinning Tires]

Ya well I lose because i have the square plug. I could do it anyway it's just that i wanted my check engine light to work and the 1988 535i doesn't have one

[euroshark]

Square plug FTW! That makes it super easy to splice. Just get yourself the pinouts, write the colorsa and functions for each set (chassis and engine) and then match them up by color, it's as easy as that! And now you don't have to stick them in that gay annoying round connector... lol

Check engine lights are for people who don't know what's going on btw. Not trying to be a dick, but M30s are oldschool, when something is going wrong you will hear it, feel it, or smell it... you won't need a light to know! Just check your fluids regularly, adjust your valves every 12 - 15k, and you should be golden!

[george graves]

adjust your valves every 12 - 15k, and you should be golden!

Thanks for the reminder - I'm clicking a bit...I need to get on that ASAP.

[euroshark]

Me too actually...

[Spinning Tires]

Check engine lights are for people who don't know what's going on btw. Not trying to be a dick, but M30s are oldschool, when something is going wrong you will hear it, feel it, or smell it... you won't need a light to know! Just check your fluids regularly, adjust your valves every 12 - 15k, and you should be golden!

thats true onlt thing is if it comes down to a vacume leak or an o2 sensor i'd rather not spend the money on a sensor for no reason. I am fairly good at diagnosing problems but on the other hand i'm lazy as hell.
and completely off topic has anyone ever taken an m30 head apart man it's a fuckin bitch. way more of a pain in the ass then the m20

[euroshark]

Fair enough, but if it doesn't work, don't worry about it, it will still be fun!

And yeah, the M30 is pretty much a fucker to take apart and put together if you only have basic tools... I spent an hour or so getting the cam in by rotating it and using a long ass screwdriver to pry the valves out of the way as needed... A spring compressor is your friend! Getting the rocker shafts out though, forget it... no easy way.

[Spinning Tires]

ya there is a giant steel dowel and a big ass hammer
ha ha