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chrispyb · Joined: 21 Sep 2015 Posts: 12 Location: Cambridge, MA

So, still new around here, think this is my second post, but definitely need some help.

Background, bought the car a few weeks ago, and everything was working well until I wound up driving in a pretty heavy rain storm and then everything sort of went to shit. My little red battery light went on, and windshield wipers stopped working

Couple of days later car would still start, though took an extra second or two, and some of the electrics seemed slower and the radio wouldn't necessarily turn on / would die. Red battery light is still glowing.

SO

After looking around, I decided to replace the voltage regulator in the alternator, and checked the belt tension while at it. did that, car turned over still, figured that was that. After it turned over though, it was showing low voltage when on, about 9.5 V. So that's an issue.

Now today, a few days after regulator swap, car won't turn over. Voltage at battery is reading 11 V give or take. So I jump the car and it drives. The battery light is now very dim, looks dimmer when driving, and a little brighter at idle.

then seems to start idling rough after awhile and finally sort of dies and won't start. I thought the oil pressure gauge was reading a little low, so I'm worried, but the oil light didn't turn on. I manage to push start the car, and it seems to run again, and this time I don't let the revs dip at idle. While driving I try to put the window up and it is very slow, and seems to even be sucking power from the car itself.

I get the car back to my parking spot and it dies again. Right before it died I was trying to pump the pedal to keep the revs up, but it didn't seem to do much, like sort of stuttered.

I jump it again, and pull it into the spot and park my other car. Now voltage on the battery reads about 11, and the car seems to make a half hearted attempt to start then nothing. What should I do?

Could a bad battery / alternator also effect the idling issue / throttle not working perfect
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'87 924S

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

Sounds like your not charging for some reason and you are running out of electricity for your ignition to make sparks so it dies..

I think you are on the right track with the alternator/regulator and possibly the alternator wiring harness.. Check your battery ground(s) and make sure your engine-chassis grounds are good, also check your battery + wires etc..
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80 Turbo - Slightly Modified

chrispyb · Joined: 21 Sep 2015 Posts: 12 Location: Cambridge, MA

So, I did note, there is the same voltage drop across the battery, as from the battery positive terminal to the engine block
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'87 924S

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

No water on the DME or inside the passenger compartment?

It could simply be that your battery is shot, but you'll need to test the alternator either way to be sure.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

chrispyb · Joined: 21 Sep 2015 Posts: 12 Location: Cambridge, MA

The car was quite leaky when I drove, coming from the screws around the sunroof where the latches attach.

Where is the DME to check / what should I look for in the battery compartment?

Also, what's the best way to check the battery? I have half a though to connect to the Audi (my dd) and let it idle for a bit, then pull it off and see if it holds charge?
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'87 924S

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

chrispyb · Joined: 21 Sep 2015 Posts: 12 Location: Cambridge, MA

New battery, and it seems to be being charged fine by the alternator.

~12.5 V when no on, about 13+ V when car was on.

Now on to replacing the wiper motor.
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'87 924S

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

chrispyb · Joined: 21 Sep 2015 Posts: 12 Location: Cambridge, MA

We pulled the wiper motor, and we could hear it trying to spin, but nothing happening. If I pulled on the wipers with it on, they'd go, but with a lot of help.
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'87 924S

chrispyb · Joined: 21 Sep 2015 Posts: 12 Location: Cambridge, MA

So, update time.

Got new wiper motor in, so they work now. Think I need to clean the contacts or replace the relay, as they don't work that well. Intermittent seems to work on the new motor, and slow speed, but no high speed.

Also replaces the voltage regulator and the battery. Battery was charging well and all was good, all electrics worked, but my battery light was still glowing. Then I was driving home the other day and I hit a bump going around a wider right, and I looked down and my battery light turned off. I'll chalk it up to German engineering and self repairing vehicles.
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'87 924S