94 325is Engine wiring harness HELP - BMW Forum

knotarian · 04-03-2009, 08:36 AM

We just did an engine replacement do to a bad head / head gasket. I'm trying to put all the plugs back together but BMW decided to you the same plugs for everything on the driver side of the engine. Most are 2 prong and a few are 3 prong. Anyone have any pics of the drivers side of the motor with all the wiring intact? i have a PDF download that may help to a point but it isn't that great. I don't want to try to fire the engine up with plugs mismatched and blow the engine.... I'd like to finish the BMW this weekend if possible.. Thanks in advance!!

talisman318is · 04-04-2009, 06:49 AM

Yeah, that's a predicament that will probably require some logic and a little good luck. Unfortunately, no picture is going to solve your problem. However, with a little bit of ingenuity and luck, you can trace the lengths of the harness' tentacles and the bends and contours in those wires and probably figure it out. What you'll find is that BMW configured the three prongers and two prongers so that the harness can be figured out. For instance, if you have same length wires you may be able to note that one plug will be inverted compared to the other one and you'll see that the bends and contours of the wires 'want' to be plugged in to fit just that way.

So, don't freak out that now you have this Octopus of wires to sort out. Familiarize yourself with the sensor locations and try to lay out the wires and note that if you have a three pronger going someplace that there is a two prong sensor, you probably haven't found all the right sensors/plugs because they will be under and behind something that you probably forgot you unplugged.

GOOD LUCK.

knotarian · 04-05-2009, 05:31 PM

OK. I got the electrics hooked up. I left the radiator out and just connected a water hose to the car for the time being. I need to hook up the small vacuum line from the fuel rail to the intake. Any ideas what this vacuum line does?

Anyways i fired the thing up and i won't idle at all. I have to keep feathering the throttle to either half or full to keep it running. It runs like its only running on a few cylinders. I changed all the spark plugs, no difference. The one thing i do notice is that it seems to run smooth at high rpm and horrible at mid to low rpm. Is this the result of that little vacuum line being off? or is there some electrical issue somewhere?

EDIT: I think i may have left one of the small wires to the starter off also. think it's related?

talisman318is · 04-06-2009, 06:31 AM

fix the vacuum leak. replace the hose. if that doesn't fix it, get a smoke test done.

knotarian · 04-06-2009, 07:00 AM

I'll run to Advance Auto today and grab some vacuum hose. I'll connect the wire back the the starter and hope for the best.

knotarian · 04-06-2009, 12:23 PM

I ran a new vac line and the problem is still there. I'll have to find someone that can check the fire for me. I don't feel like getting shocked 6 times...

Is there any other suggestions?

612wade · 02-07-2010, 04:06 PM

I have a 1994 325 is. That little vacuum hose could be the fuel pressure regulator. disconnected will create a rich condition. Also, on my car when I disconnect the mass air flow sensor it idles rough, but does idle, and smoths out as I rev it up. I have known wiring harness problems with my car that Im trying to figure out.Im Looking for a new harness.