no start, car abandoned, help greatly appreciated

[kronus]

This is a follow up to this thread.

Car is a '87 325e, nothing abnormal in the electrical system. Bav Auto plug wires.

I drove down to mail a package, and when I get back to my car, I get the same no-start situation as described in that thread. This time, however, it does not magically fix itself.

All fuses are intact. Relays should all be good. When I try to start with no jumper cables, the starter doesn't even budge. However, the coil charges and the entire electrical system clicks on and off repeatedly. When I close the door after attempting to start it like that, the interior lights stay on. (wtf?!?)

When jumped, it cranks over, starting slowly and gradually increasing in speed. Does not start, however.

We then attempted to push-start it, which was unsuccessful and almost completely drained the battery. (why would it do that?) After that happened, an unpleasant buzzing noise came from the front left speaker area unless the door was closed or a load was placed on the system. I do not have the door ding dong in the car.

Fuel pressure is good. When we tried to see if we were getting spark, the system drained the battery with an outcome similar to that of our push-starting attempt.

Any ideas on what could be wrong?

Our guesses are a combination of any of these:
bad starter
bad grounds in engine compartment
bad coil


Car is currently in a parking lot a couple miles from my residence.

[jlevie]

There could be a problem with the primary power connections, but everything that's described indicates a dead battery. If the battery is deeply discharged, a short connection of the jumper cables may not charge the battery enough for the system voltage to rise to the point that the DME can function. Thus preventing the engine from starting. You might be able to get it started by charging the battery via jumper cables. That may take 10-15 minutes with the donor at a fast idle.

[Farbin Kaiber]

I really thought it was extreme low voltage. The other related potential symptoms are, this same issue had arrisen when we installed the euro bumpers and removed the battery. I jumped it and after a short time it was ok. So, I attempted the same thing again, but with my power probe connected, with my car at idle, I was getting a reading of 14.1 max out of the e30. We did get cranking, fuel, and spark, but after attempting to pop start after that did not work, we went down to 5.1-6.7v in the system.

I was thinking there may have been a loose connection issue after we disconnected it before the last time this came up.

I'm gonna slow charge a battery in the garage so I have one to take back to the car this afternoon.

[E30_fiend]

I've had similar problems before but not on an E30. All signs pointed to the battery and or coil/ignition system. I checked all that and nothing. What it ended up being was the alternator. It was drawing power when you tried to start it which ultimately cause the battery to die and the car would not start.

See if you guys can start it with the alternator disconnected. Disconnect the wires and throw some electrical tape over them and see if the motor with start. Another reason I think it may be your alternator is because you noted a humming noise coming from the speakers. In badly powered stereo systems, the alternator can get over worked and begin making a noise the only way it can. Through electricity.

I'd put my money on the alternator kronus.







Taylor

[StereoInstaller1]

Checked the motor grounds? How about the main body grounds?

[Optimator]

It's too bad you don't live in God's Country. Mr. blunt would probably be able to suck start even a European M20B25.

[Farbin Kaiber]

For some reason I think his car fried my Power Probe.

[gearheadE30]

I going to guess grounds as well, especially if that many different electronic components are messed up.

[OrganicMechanic]

did you check the Pulse Generators?

[kronus]

did you check the Pulse Generators?

Not sure what that is.


I'm going to go down there and check grounds and some other stuff. (if the car hasn't gotten towed yet :()

[kronus]

OK, I checked out the grounds. There is absolutely no voltage drop between the engine and the body. I cleaned the rear battery ground, the upper engine ground (under the diagnostic connector), and electrically inspected the oil pan ground (it was good).

Rob, no, the battery does not throw big sparks when connecting/disconnecting.

I'm beginning to think that the battery is dead, not just discharged. I charged it for about half an hour today from a jumped car, and key in the ON position made everything look fine (illuminated, lights, OBC, check panel, etc).

However, with the jumper cables disconnected, when I turn key to ON, interior lights go out and the cluster does not light up.

[Optimator]

Mr. kronus, I bet you have a dead cell in your battery. It may check out at 12.5V, but it is probably toast. Is there an aftermarket stereo in your car? If so, many times a speaker wire or some power wire starts to touch the chassis and can cause havoc with your electrical system.

OrganicMechanic probably meant to check the bell housing pulse generators, which allow the DME to know the position of top dead center and also to determine if the starter is turning the engine over quickly enough for it to run. If it is spinning quickly enough, the DME will power up.

Sometimes, these randomly stop working, but if they did, this would cause a no-spark condition. However, if you checked for spark, and saw spark, you should be able to cross this off your list. You can check the resistance of the sensor and wiggle the sensors. If the resistance spikes to high, it is a flaky sensor.

[kronus]

negative, herr Optimator.

Car's back now. We disconnected the alt and it started readily. Then, reconnecting it and whacking it a few times let it run continuously and normally.

Alternator needs a rebuild. E30_fiend wins a cookie :D

Thanks for the help, guys

[Farbin Kaiber]

Optimator is wrong battery is good, I checked it.

[chileelky]

Had the same problem. Though was the battery, new battery, then alternator, repaired, but turns out the alternator was not getting "excited" with 12v prior to crank it, hence no power generation. That cable (blue one out of the alt) goes to the conector attached to fuse box on early e30s (one of the 2 at the bottom of the conector, was rusty) and then to the dash panel, blue conector at right side. Check for 12v at that cable with ignition switch on.