DOHC swap & OBC functions?

[bmwpower]

I use my total miles left and MPG almost daily. I think it would be worth it if it looked stock or close to it.

There's got to be a way to get it to work with the E30 OBC though.

[Ablice]

The e34 obc?

i'm not feeling like typing out caps today. but, the thing is the e34/32 obc is shoved so close to the radio. i'll need to make a custom bracket since the e34/32 obc is secured differently (quite differently) than the e30 obc is.

i can get it to work off the e30 wiring. wiring is pretty straight forward, took me hours to find out what little information was already on it. groveling through wiring diagrams and all. the e34 wiring diagram is not as concise as the e30 one is, for example on the e30 diagram it'll tell you pin 15 is for fuel level input, 22 is start input, 16 is outside temp input, etc. but on the e34 obc diagram you have to deduce where everything comes from. right now my notes for the corresponding e30 stuff i just mentioned, pin 5 is temp sensor, 26 says "comes from fuel tank level" (i had to trace everything, it doesn't tell you what that pin does), 10 is "comes from start signal".

basically i had to fill in what was generously omitted on the e34 diagram on what does what. good thing is most of the e34 obc stuff is junk on the e30: for example, pin 3 and 16 are diagnostic link, e30s don't have that, pin 20 and 21 are parking venilation (e32s only, e34s don't have that), e30s don't have that. what's more is most of the crap i have yet to figure out. for example i know that pin 24 comes from the dme, but I have no idea what it does; as for pin 7, all i know is it comes from the check control or somehting.

should i really pursue it? it would look tight in an e30, and as far as i know i've never seen an e30 with an e34 obc. the only one that came close was a M3 with a e34 dash shoved in it. or some thing fancy was done to the e30 dash. any way you put it there's a e34 hvac panel shoved in there link

about halfway down. the op's b6 3.5 is flippin' sick. but that m3 with the alpina bi-turbo engine is ...omg. how much power do you need? it could fly

guys, you think i should do it? obviously for me that's a lot of work, as i have nothing here...no garage, nothing.

[Ablice]

lots of interest here.

am i all getting blank stares?

[BDSax]

i rather my stock obc to work.

[PiercedE30]

i rather my stock obc to work.

I've decided to yank mine out.

[BDSax]

i want my m50 swap to look totally stock. i want all things to work as it did with the m20.

[Ablice]

Well you guys got it easy with the stock 13 button OBC. All you need to do is get some kind of data thing that can transform the 24v DME fuel rate input into something that works accurately for the OBC.

The e34 OBC on the other hand, is another story...it would work right with the fuel rate input (mine that is, coming out of a 525i M50/M50TU, I didn't check the year) if it doesn't have the coding plug shoved in the cluster, but the e34/32 obc is tight though...would be interesting to wire it up through the console for like a "information display" for the rear seat passengers...

would be real useful for me, I am nearly always the only occupant -.-

thanks for all the input. seems like this is a very popular mod a lot of people would be pushing for. /sarcasm

[BDSax]

im all for a working OBC, but i want the e30 one.

so would you jusdt tab out of the DME? i have a buddy that knows all kinds of electronics that i want to help me. and info you can give me to point me in the right direction?

[Drew325is]

Well you guys got it easy with the stock 13 button OBC. All you need to do is get some kind of data thing that can transform the 24v DME fuel rate input into something that works accurately for the OBC.

Where do I get some kind of data thing can tranform the input?

[Ablice]

Phew I dunno.

Ask around. They exist. People have used them on e30s too.

[BeirBrennerE30]

you kinda need to make yoru own... the computer calculates fuel economy using injector pulse width. So every injector size will need a different conversion module.

[bmwpower]

you kinda need to make yoru own... the computer calculates fuel economy using injector pulse width. So every injector size will need a different conversion module.

But doesn't the signal carry over one cable?

So is it the frequency you need to change? Is that it? Is it a linear change?

Anyone with a scope??

[BeirBrennerE30]

yep... there is one wire that is surprisingly easy to get at that both the mpg meter in the cluster and teh OBC use to cal the varius numbers. I have no idea what signal my car is getting and what one it needs to acurate. I believe its a black wire coming out of the computer but i would need to double check.

If a couple people with a working e30s m20b27, m20b25, m10b18, etc could tell me what signal is in that line across the range. i could probably come up with some conversion box with dip switches for the various engine combos(assuming the signals are different) and different injector choices.

[Drew325is]

I've been thinking about buying an oscilloscope for the purpose of getting the E30 obc sorted. I've always assumed the OBC read injector pulse width...but is it one injector? a number of injectors? etc etc. From memory the signal from the motronic comes for a solid state point on the motronic board, so the signal could be anything really. The only way to work it out is with a scope. In my case...I'll also need to do it whilst the M20 is still in the my car and running. Maybe I should check with my autoelectrician, see if he has one. Otherwise they're pretty expensive things to buy.

Do we know of anyone who's ever actually made an oscilloscope trace of the signal?

[bmwpower]

I've been thinking about buying an oscilloscope for the purpose of getting the E30 obc sorted. I've always assumed the OBC read injector pulse width...but is it one injector? a number of injectors? etc etc. From memory the signal from the motronic comes for a solid state point on the motronic board, so the signal could be anything really. The only way to work it out is with a scope. In my case...I'll also need to do it whilst the M20 is still in the my car and running. Maybe I should check with my autoelectrician, see if he has one. Otherwise they're pretty expensive things to buy.

Do we know of anyone who's ever actually made an oscilloscope trace of the signal?

If you can't get a scope, I might be able to. I could probably get one of my garage buddies to run the scope on my car.

Does anyone have an E30 electrical troubleshooting manual? Would that help any?