CrazyCoolCars

I've got what seems to be an escalating electrical problem with my car. It started a couple weeks ago with my tach wobling and wandering and I thought it was just my tach going. Yesterday the car started cutting out for a second or two and as I watched the dash and lights, nothing else seemed to be affected except the tach which would be pinned for the moment it cut out. Today on the way to work, the engine actually stopped running and required my restarting with the key. Anyone have a clue? Overall the car has run well and without glitches to this point.

Doug

87 911 Carrera 3.2 with G50 box

old man neri

Have you checked all your grounds?

CrazyCoolCars

I'm still new to the car. I replaced the main ground which goes from the gear box to the chassis earlier this year when I changed the started.

Where are the additional grounds?

Wouldn't I loose the lights on the dash if it was a ground problem though?

DRACO A5OG

Hey Doug,

DO you have a spare DME Relay? This is a must in anycase.

Swap the DME relay underneath the driveside seat. If you do not have one tap on the DME relay the solder tends to break if it is original.

Jim

Edgy01

Sadly, your 1987 car is now over 20 years old! What this means is what the old man suggested,--start with grounds. Once you attain that age you have to religiously check and clean grounds on a regular basis. BUT, you need to locate them all. I would suggest to all 911 owners that they purchase the factory manual and go to the electrical section, and get to know where all the pertinent grounds are. You may be surprised to find that there are something like 12 critical grounds in that car, and they all contribute to that car running smoothly.

A rough tach tell me electrical problems are the issue,--and one should always start with ground . Personally, I would redo every electrical connection in the fuse box to make sure they are good and clean. (This is one reason I ultimately had to abandon any pre-1989 Porsche,--electrical aging. The newer cars use the newest style of fuses and are less prone to issues).

Relays,--same issue. Have spares and stay on top of their electrical continuity.

nineoneone

Pull the distributor cap and check for water.... ask me how I know!

dshepp806

Are you monitoring the voltage reg function?

Best,

Doyle

DonMo

Check this link out on pelican.

http://forums.pelicanparts.com/showthread.php?t=391126

rw229

Crazy tach? Flickering dash lights? I'd put my money on the voltage regulator and be prepared to rebuild/replace your 20 year old alternator as well because you'll find a nice groove worn in it.

At idle, meter across the battery or take an old accessory cord that you can hook a meter to, plug it into the cigarette lighter and drive around. More than likely you see spikes to 17-18v. Your DME will be very unhappy and the car will die.

You may end up replacing the battery as well (have it tested) as it also does not like the spikes.

Good luck, BTDT with two different Carreras.

CrazyCoolCars

I appreciate all your reply's and information and am anxious to get under the darn thing and fix it but, I'm getting married in two weeks and the Fiancee seems to thing I should be doing something other than trouble shooting the problem child. Thanks for all the info, I have a long checklist to run down when I finally get a minute and I'll let you all know what the culprit is...

theiceman

Man better get a handle on THAT sitauation and FAST .. and i am NOT talking about the car :-)

CrazyCoolCars

OK, I've got 1 weeks til the big day and had some time to work on the worsening problem.

I've...

Put in a new DME and done the complete list of checks in the Porsche manual and it is working perfectly.

I've checked every ground I can find and they all look good.

I've checked the voltage across the battery and it is a steady 14.0

and...

I still can't drive to the super market for milk without it conking out somewhere between here and there...lol

HELP!

pingman

crazycoolcars, I had a similar problem, which I made worse by jumping to conclusions rather than a methodical approach. My problem was an intermittant DME relay which you have already replaced. The Dumb thing that I did was start working on the top dead center and speed sensors before I replaced the DME relay. I replaced both of these sensors and still could not get the car to start. Replaced the DME relay, no start. Engine would turn over but not run. The fine people at Systems Consulting gave me instructions on checking the ohms and voltages on the "brain". The Iceman was also a great help. What I finally found was that one of the new sensors I had purchased from a Porsche dealership was bad. Call
Systems Consultants at 310-545-3716. They are in Calif, and you may find a problem with the brain or these sensors which can become loose or fail due to insulation rotting away. the Bently can give you a location and picture. Mark.