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hello all.....this being the most informative of the bm forums I have question that has not been fully answered.....the use of a auto m30 engine harness and engine in manual installation......from previous threads it seems that just the TPS wiring needs to be altered....is this the case???.....I have a manual 79 e12 based manual 635........it had the ljet setup but was goosed so only replacement that was convenient was a 87 e32 auto 635 engine and harness....question is what wiring changes need to be made to the auto harness to run her.....it suppose some changes need to be made to the various connectors close to the ecu(e32 setup)........

From what read you are tring to convert your 79 635 to motronic 1.3 I did that with my 78 530i you can use a auto harness if the car you converting is manual you remove the auto stuff from the harness

here is a pics of it
http://tinypic.com/usermedia.php?uo=TCh ... h4l5k2TGxc

nice install and thanks for reply....from what i have seen of other conversions yours is quite unique.....from looking at your cold valve on throttle body..you are running motronic 1.3 i assume...most people seem to just horse in the newer m30s.......The jetronic engine that was in my car was fried and it would have taken ages to find another (being in jolly auld ireland)so I went with a 87 e32 735 auto replacement......have it in now and is cranking but not starting.....am trying to rule out the possiblity of the auto harness inhibiting startup some way.....at the ecu connector there are 4 connector that I believe plugged to the auto box ecu (we don't use tranny in description of car components this side of the ocean!!!! ) the biggest being a eight hole block with 7 pins in use.....then there is one 3 pin and two connectors with 2 pins.....Is there any small mods made to this harness to make it would.....i feel i am very close to getting the whore to start......of course getting accurate wiring diagrams is also proving difficult for euro models.....

If it turns over but does not start, I think you can rule out problems related to the auto box connections. Engine / gearbox connections are just a signal that tells if it is in gear or not (will not turn over if in gear) and another one that goes from the TPS potentiometer to the gearbox calculator so that it can shift gears adaptive. Or at least, that is how much I recall from my E32.

Try to figure out the obvious things first (power to motronic, spark, fuel. RPM pick up).

I just mounted a 3.5 motronic engine in my E12, actually takes very few wires to be connected from the engine harness to the car in order to run; permanent 12V, ignition 12V, starter 12V, fuel pump 12V, and some grounds (not sure if this is the complete list ). Of course you also want alternator light, RPM, coolant temperature, and oil pressure, but it does run without those as well, for a while at least..

Oh yeah, my engine was from an automatic as well, my car is manual, and I did not make any modifications at all to cover this difference. It runs, but rough, my MAF is bad and I might have some air leak somewhere.

LE: Have a look at this topic: http://www.mye28.com/viewtopic.php?p=758206

Thanks for the inputs.....turns out i have a fuel problem......there is pressure at fuel inlet but possibly not enough.....replaced the regulator with a spare and by passed one of the fuel filters......there is fuel in the rail but nothing coming out the return pipe......unfortunately i do not have a fuel pressure tester however I am assuming the pressure is not sufficient or my injectors are not triggering for some reason.......

There should be plenty of fuel coming from the return. So that seems to be where your problem is: fuel pressure. Is the pump working ok?

fuel pump was knackered...car starting and running now happy days but engine is racing and settling down to normal idle momentarily before racing again in cycles......any ideas???

Mine also oscillates, bad MAF and maybe also an air leak. On idle RPM it runs rough, then almost stalls, and then accelerates. Motronic idle control can behave funny when something is not right.

found few vacuum leaks air and there idling better now.........got oil leak from flywheel/ bellhosing.....that sucks donkey dick.....read the bolts attaching the flywheel can leak oil......i'm suprised the bolts are supposed to seal oil too!!!!! crank seal was not replaced......''not apparently broke so didn't wait a month to get part to replace it''..... getting new seals and gaskets here is time consuming
must wire up the rev gauge on dash........would i be running a wire from coil???

Yes You run a nice thick wire from the - of the coil to the black wire that comes out of the fuse box.Do not use the black wire in the harness is too small of gauge

black and yellow is for starter
green and purple is for the fuel pump
green and brown = oil pressure
green= switch power
blue wire from small conector to blue on fuse box

Murphy states that you should always change that seal in the back when you have easy access to it.

I am surprised to read that the thickness of the tacho wire matters. Never had any issues there, the current should be low, it's just for sensing. I am planning to take mine from the diagnosis plug, the install might be a bit cleaner that way. If not possible , I'll put an extra wire on the - of the coil.

the most would be 10 gauge any where between 10-14 gauge wire would be fine

anyone ever weld in couple flexible exhaust pipe sections.....might refine the exhaust a litte and take pressure off the manifold....had two cracked manifolds on two engines....luckily the manifolds were flanged between cylinder 3/4 so got one good manifold from the 2.........just a thought......

coil wire i just took black one from old loom.....about 1mm square cable.....my e12 based 79 e24 car has quite thick silvery coloured wire in its cables that are unnessecarily thick for use in some applications but used anyway.....i guess copper was lot cheaper 30 years ago.....

by the way my 79 e24 owners manual is the ultimate....wiring diagrams, specs on everything......maintenance chat.....more like a little haynes manual or bentley......they don't make them like they used to!!!!!!

I connected my RPM yesterday, straight from the - of the coil to the fusebox connector. Used 0,75mm wire, works like a charm.

thirdrocker wrote: by the way my 79 e24 owners manual is the ultimate....wiring diagrams, specs on everything......maintenance chat.....more like a little haynes manual or bentley......they don't make them like they used to!!!!!!

Agree. There is a lot of info in there, compared to modern ones where you can find all about the number of storage compartments for coins but not what kind of spark plugs it needs.

hey falkenberg i want to ask where did you place your ECU in your car.....i understand your hareness is from an e32 so is quite short and won't reach into the glovebox where it would be out of the elements......mine is placed in front of glovebox area in the bulkhead at moment and i made a cover for it but its still in a venerable place......did you make a complete sealed enclosure for it or something or cut all the wires and extend them!!!!! extending all those wires would be my very last resort although it would be tidy to have ecu in glovebox.

anyway any ideas???
and how did you get on with that erractic idle you had earlier.....mine idles a little bit erratic at moment.....just small flucuation. never slights to want to stall just i can see the rpm needle shaking a little