M30 Issues.

[msinger]

I have a swapped M30b35 from an e32 in my 89 325i. i am running the m20 wiring harness with the 150 computer from the e32. i have been driving it for about a month, the first week i ran it off the m20 computer then the last three on the m30 computer. it was running like a dream occasional near overheats because of air in the coolant lines.

when i was bleeding the system the other day it suddenly wouldnt start up. then a couple hours later it started and i drove it around the block it ran perfectly as usual. now it turns but wont start, or starts and runs for maybe 30s and dies.checked the spark and fuel and neither are working, tried changing the crank sensor and at first it seems to fix the problem, then 45s later it shuts down again, and im back with the same issue. checked the crank sensors we were using on my buddies e30 and they both worked fine on his. looking for help, is there an issue with my relays or something? complete mystery to me...... thanks for the help!

[chadthestampede]

Part of the problem could be that the m20 computer and the harness is made for motronic 1.3, while the 150 ecu is running motronic 1.1. Just a thought.

Commonly the relays are a problem though, so I would try to swap them with known good ones and see what happens.

Also from what engine are the temp sensors you're running?

[Erick]

Part of the problem could be that the m20 computer and the harness is made for motronic 1.3, while the 150 ecu is running motronic 1.1. Just a thought.

Commonly the relays are a problem though, so I would try to swap them with known good ones and see what happens.

Also from what engine are the temp sensors you're running?

Um, what?

If he's running the M20 harness (Motronic 1.3), then you'd never be able to plug a Motronic 1.1 ECU to the harness plug.

[chadthestampede]

Um, what?

If he's running the M20 harness (Motronic 1.3), then you'd never be able to plug a Motronic 1.1 ECU to the harness plug.

haha, uh, right i didn't think of that lulz. But he does say "i am running the m20 wiring harness with the 150 computer from the e32."

and

735i/iL
E32
M30/B35
86-88
0 261 200 150
Bosch Motronic M1.1

so there's something wrong there, no?

[Erick]

I didn't know E32s came with 1.1s. I thought that was done after E28s. If all he posted is correct, then yes, something wrong is going on there.

[RickSloan]

im almost 100% your problem is bad relays seeing as how you described my porblem from last week, i replaced the relays and i just drove the car 800 miles yesterday

buy new relays and all should be good

[msinger]

interesting, the motor i have is from an 89 though, but why would it have worked and now intermittently stop?

[msinger]

we checked the relays in the fuse box, they all seemed to be working alright, but not the main relays on the side of the bay, ill check those out. thanks for the help

[msinger]

which relays did you replace?

[RickSloan]

the main and the fuel and the other one in that cluster of 3 for shits and giggles

they heat up and thats when the dont work, then when they cool they work again

[BDK]

Ok, couple of things...
The E30 M20 is 1.1 or 1.3, the e34 M20 is 1.3
The 150 Ecu can be 1.1 or 1.3, because the early B35 (E24) run 1.1 mit 150 ECU, but I have heard that early E34/E32 B35 also run the 150 and they are 1.3...
150 ECU can be used with either from my research...
I even know people who are running 179 ECU 1.3 thru their 1.1 plug...all are 55 pin
E28 is 1.0 and 24/28 PIN, you can't run these thru either due to the different number of PINS


The problems you have listed sound very much like bad relays or a bad ecu as in corrosion on the board and need resoldering

Do you have or have access to another known good ECU?

[msinger]

yes i hooked up the old m20 ecu that worked previously and had the same issues.

thanks for all your help guys, turns out it was the relays! big props goes to RickSloan for the diagnosis!

Speaking of ECU's though i am looking for a 179 ecu if anyone has one laying around, apparently they respond best to chipping.

also if anyone knows any good tricks for bleeding the system, i'd like to be able to get it on the first try instead of the 10th...?? thanks again!

[BDK]

for really stubborn m30 bleeding,
I find backing up a steep hill works (after the fill)...
I dunno why, but it worked for me but I am now living in FL so that will now be impossible...
Before the fill, get the front end as high as you can then fill it up...

[george graves]

Um, what?

If he's running the M20 harness (Motronic 1.3), then you'd never be able to plug a Motronic 1.1 ECU to the harness plug.

BDK is Right

Umm yea, 1.1 and 1.3 are interchangeable unless I'm off my rocker.

I squeeze the crap out of the hoses while beading(motor off) - works for me.

[RickSloan]

i find when it gets real frustrating too, just driving the damn thing or revving it good with the heat on does the trick