Stripping Cental Locking and Electric Windows

#1

At the stage where I’m trying to cut down the harness and I’ve seemingly run into a bit of an issue.

I’ve got NASCAR bars so, window regulators and motors are out, along with the central locking. I traced wires from the window motors, switches, and locking system to the firewall and started removing them.

Once I got to the firewall, I stopped to check and make sure the car still ran… annnnd the answer is sort of. It doesn’t want to idle smoothly, when it does run, it’s probably like 600ish RPM?.

Turning on any accessories like the lights, or giving it gas typically will make it stumble and stall. Right now the Dash is completely removed without the cluster plugged in.

Any ideas what could be happening?

Video of the slow idle and stumble when I give it gas.
Youtube link

Cut Off
Passenger power window wiring (kept the mirror wiring)
Passenger door lock
Gas Door actuator
Driver power window wiring (kept mirror wiring and adjuster thing)
Driver door lock

#2

I can’t think of any wires around there that could cause this symptom therefore my guess is that the wire cutting did not cause the problem.

Lots of things to check when your engine is running like crap. Start with reseating every wire connector that has anything to do with the engine. Then push and pull things looking for a vacuum leak.

Confirm spark plugs at ~22ftlbs. Put fuel pressure gauge on fuel line…lots of things to check.

This would be a good time to install a fuel pressure gauge, and air/fuel meter on your dash. Those are very helpful when the engine is acting up.

Your engine running quite lean would fit the symptoms.

#3

Thanks, I’ll start with re-seating the C101, when I plugged the battery back in, it didn’t start at all because the C101 was unplugged :blush:

Then move on to the spark plugs, etc. etc.

#4

No luck with that.

I put a multimeter lead on the positive terminal of the alternator and the negative to the closest ground I could find and seemed to get 9v??

Seems like the alternator is bad? Would it cause symptoms like this?

I did have to jump start the car, but I typically have to do that after it’s been sitting.

#5

Fully charge the battery or get a new one. Low voltage will cause all kinds of funky performance misfires.

RP

#6

is your gauge cluster plugged in? if not, you’re cutting out the alternator exciting circuit to start the charging.

#7

Really??

No it’s not plugged in. I wasnt aware this would have an effect.

I also took off the voltage regular and the brushes are quite worn, so I’ll be soldering on some new ones.

#8

Patton’s certainly right that a low system voltage can cause some wonky engine management behavior, but that doesn’t mean low system voltage is the cause of your problems. Easy to check too. Pull out the Bentley and see what the spec is for voltage while running and not and the places it needs to be tested.

Voltage problems can be a little tricky in these old cars. Be distrustful. Everything that seems to be ok could be fooling you. Every connection and ground should be suspect. The engine harnesses are all in terrible shape with the copper tarnished inside each crimped connector. The tarnish is so bad that it reaches up inside the insulation for several feet. Tarnished wire is no issue but tarnish in a crimped connector is a problem. Some have bought new engine harnesses ($500?) so they can be more confident of good connections.

If you get serious about testing your electrical system, check voltage not just at battery but also at the power buss on the firewall forward of the passenger.

If you decide to go after the electrical system, pull apart the connections and grounds and hit them with a wire brush. Then dab on a little conductive grease before refastening. Do same for all connections to engine harness.

Voltage regulator’s are cheap. Might want to replace vs. repair.

Even tho I talked a lot about system voltage, that doesn’t mean that’s your problem. There’s an old thread where I went bananas chasing electrical gremlins. I’d had engine management problems for months and it was kicking my ass. I found what I perceived to be evidence of voltage a little low at the DME and went on the war path attacking possible causes. A couple months later I figured out that the problem was a bad AFM so had nothing to do with the electrical system.

#9

Thanks Ranger, much appreciated! I’ve got a list of things I need to try, hopefully I can tackle some of this tomorrow since like most people, I won’t be working.

Just signed up for CMP in Feb and RA in March, so I’ve got some time to get it sorted out. Looking to go to comp school in June at RA.

#10

For now, just plug the cluster back in and start the car to check it. Before starting, check to make sure the battery light comes on when you have the ignition in the ON position. That light is part of the excitation circuit. After started check voltage at the batttery for 13-14V. The car should run amazingly better at 14V as opposed to 8-9V.

#11

This will definitely be my first step.

The alternator brushes do need replacing however.

Thanks!

#12

+1.

IIRC charging voltage should be 14-14.5. If you get 13.9 or less at 2500rpm or better, exclaim “lets check Ranger’s #'s with the Bentley.”

#13

Thanks to both of you!

Plugged in the cluster and eventually (I assume after charging the battery) everything ran great again B)

I ran into issues where the tail lights were on when they should have been off, and off when they should have been on, and the gas gauge wasn’t reading correctly. Turns out I left the ground undone after painting the rear seat area… :blush:

Have a fun and safe New Years!

#14

[quote=“ecrawshaw” post=79911]Thanks to both of you!

Plugged in the cluster and eventually (I assume after charging the battery) everything ran great again B)

I ran into issues where the tail lights were on when they should have been off, and off when they should have been on, and the gas gauge wasn’t reading correctly. Turns out I left the ground undone after painting the rear seat area… :blush:

Have a fun and safe New Years![/quote]

no problem. be careful when ripping out the ‘unused’ wires. there are a ton of splices that bmw used all over the harness and cutting one wire may inadvertently kill power to something else you need. For a chump car i had an entire harness on my garage floor and thoroughly ripped out every wire that wasn’t needed after verifying each one. when i was done, i had 9 lbs of wire taken out. was it worth it? for the amount of time it took to do it correctly, not at all.