DOHC swap & OBC functions?

[ed94r]

Is there a way to wire the OBC so that the range, avg mpg, and (probably related) the fuel mpg guage work. All other check/obc functions work.

TIA.

[Brew]

AFAIK, there isn't any simple way to do it.

Check through the DOHC thread; I think somebody explains it.

[Jason89i]

Re: DOHC swap & OBC functions?

All other check/obc functions work.

TIA.

not sure on the obc, but the mpg meter on the dash will not function correctly.

Did you get the oil level warning light wired?
Did you get the service interval lights to reset?

im still having trouble with them.

ITEM #1: anyone figure out the oil level sensor with the e30m50? ive heard the e34 oil level sonsor runs a different resistance and will trip the active check control panel. anyways, i couldnt get the e34 sender to work properly. should i just ground out the pin#10 (blu/wht on e30 harness) or should i just wire up the e30 sender and zip tie it upside down in the engine bay. i hate to sound like a hack, but ive had mine for over a year and i still dont have it functioning correctly.

ITEM #2: i cannot reset my service indicator lights. i plug in the reset tool, but the tool is not getting power. lights wont reset. should pin #16 (wht/blk e30 harness) be hooked up to ???? needless to say, its very annoying.

any input greatly appreciated. thanks

[ed94r]

I'll get back to you in a few once I talk to the guy who wired my conversion. He was able to get all the check functions on the car to work. My SI lights/reset and my oil check light didn't work at first but he figured it out (with help from the guys at Sports&Imports).

I seem to recall something about the DME not getting a source of power for the SI/resets.

Ed

[Ryan Stewart]

I havent screwed with it yet because I wasnt that concerned with it but if you find a solution please tell. Early or late car on the white wire? I can check mine again if its early.

My MPG functions dont work. The fuel usage system doesnt work. So it says I have infinite mileage and use 0.0l/km. The functions that only rely on the body wiring harness work, of course. If I am a bit curious about mileage left I just use the 1000 1 trick and see how many liters I have left. Its pretty accurate.

As for MPG, youd have to do the math anyway to get an accurate number. Since winter (and no traction no fun) I have been getting around 26mpg average.

[ed94r]

I havent screwed with it yet because I wasnt that concerned with it but if you find a solution please tell. Early or late car on the white wire? I can check mine again if its early.

My MPG functions dont work. The fuel usage system doesnt work. So it says I have infinite mileage and use 0.0l/km. The functions that only rely on the body wiring harness work, of course. If I am a bit curious about mileage left I just use the 1000 1 trick and see how many liters I have left. Its pretty accurate.

As for MPG, youd have to do the math anyway to get an accurate number. Since winter (and no traction no fun) I have been getting around 26mpg average.

Yeah, even if the #'s aren't accurate, i still had baselines that I used on the M20 that I would like to compare. Another reason is that I'm kinda wacky about everything working...

Mine is a '88 325is. 6/88 I think.

I believe there's a guy @ Sports & Imports who has figured the whole thing out. I'll try to go see them sometime this week...They've done 20 + conversions.

[NickP]

I have the wiring done for both.

The oil level light was easy, you need to build a small harness from the connector at the oil level sensor to C101. One of the wires goes to ground the other 2 go to the C101 - I know this is vague so I'll try and dig up the details for it.

I also have the fuel consumption thing working although it is way off - if anyone's figured a way out to calibrate this - POST HERE!!! :D Since mine's a 1987 I had to make the connection for this around the glove box - to the ECU. I don't know if later models go through C101 ala the RPM signal. Again this is vague I'll dig up the details and post them this weekend.

[ed94r]

I was wrong. The guy's gonna try using the E36 OBC to arrive at how to make the E30 OBC work. His OBC works (he drives an S52 E30 cab) but like the guy above, it's not accurate.

When he figures it out, i'll chip in some $ so that he can help w/ mine.

Ed

[gstuning]

I havent screwed with it yet because I wasnt that concerned with it but if you find a solution please tell. Early or late car on the white wire? I can check mine again if its early.

My MPG functions dont work. The fuel usage system doesnt work. So it says I have infinite mileage and use 0.0l/km. The functions that only rely on the body wiring harness work, of course. If I am a bit curious about mileage left I just use the 1000 1 trick and see how many liters I have left. Its pretty accurate.

As for MPG, youd have to do the math anyway to get an accurate number. Since winter (and no traction no fun) I have been getting around 26mpg average.

you mileage isn´t working since you either didn´t connect the MPG wire or you didn´t connect the speed wire into the DME

[Ryan Stewart]

I have the speed connection on but I didnt connect the mileage because, like stated here, the systems are incompatible. Its not a useful system if its innacurate.

I will probably just wire up an oiltemp sensor in place of it someday. That would serve me a better purpose than the "how much fuel I am supposedly using this second" gauge.

[sharky]

has anyone tried a e36 obc and mount it somewhere around the ash tray? I dont know but it makes sence.

[ian332isport]

I'm working on the MPG problems on the OBC. Will have it working shortly. Just need to get my car back from the Bodyshop before I can finish it off.

The problem is all down to the fuel rate signal coming from the DME. The signal is the same type (square wave), but the frequency is different (higher), so the E30 OBC always gives very optomistic readings.

I had a similar problem with my tacho, but not quite as extreme. I used a calibration module from Dakota Digital to fix the tacho, and the same unit should be able to do the MPG. I will swap my tacho unit into the MPG wire, and check it works before I order another one though.

Cheers,

Ian.

[Drew325is]

Sorry to dig up an old thread, but Ian is there any news on your solution to this?

[Ablice]

I'm planning on a E34 OBC swap.

Not M50'd yet, but planning.

All I need is figure out the wiring. Maybe in 3 weeks that'll be coming. I'll probably modify a spare HVAC panel, and use small radio to make up for the less tall but wider E34 OBC.

I thought a E36 OBC but it's just too big — bigger than a radio. Looks nice though, but the buttons are not E30 appropiate.

[Ablice]

I got most of the wiring worked out for the e34 obc, such as this - to - that, etc.

It'll fit in a E30. The way to do it would be to shove it in-line with the radio. After you put it all together, radio faceplate to OBC faceplate there is 1mm to work with. You have to hack the OBC in half literally, but it should work.

The reason I'm putting it off is that the e34 cluster register a different kph/hz signal, so the speed input into the e34 obc is going to be wrong.

The tight thing is I pulled the OBC from a e34 m50, so when I do the swap I won't have to fiddle with coding plugs. There are a lot of e30-useless wires on the e34 obc, mostly relating to check control and park venilation (7 series only).

I want to get it in but I'll need some sort of modulator to convert the signals from the speed input into accurate digestable information for the obc, which I don't have yet, and I'll need another one to go into the cluster from the DME so the fuel economy gauge works right.

gah. also once i hack up the E30 obc wiring harness I'd have to make a custom obc holder, probably one for the radio too. would look evil once finished, if it's worth it? the e34 obc does have secret functions ^_^ like instant L/100km readings, instant km/hr readings, among a few other things. do you guys think it's worth it?

seriously...