Weirdest Problem Ever

JonVaccaro · 08-10-2003, 02:15 PM

Try this one on for size. I've been having problems starting my '86 944 all week. No spark at all, but the engine turned over fine. After checking a handfull of things, I unplugged the wire that goes from the coil to the distributor cap where it meets the distributor cap, put a screwdriver in the loose end, and set the screwdriver down so that the metal on the driver was about an eighth of an inch from the engine block. If the wire was getting electricity, I should see a spark when I cranked the engine. Sure enough, I turned over the engine and it sparked. I plugged the wire back into the distributor cap, turned the engine over and viola! the car started immediately. I figured the wire must've been loose in the first place so I drove away thinking I had solved the problem. That afternoon I found myself stuck in the parking lot of Quiznos with an engine that again, would not start. I plugged and unplugged the distributor cap wire a half a dozen times to no avail. I couldn't figure out what was wrong. Then, on a whim, I unplugged the wire again, put the screwdriver into the loose end, sparked it, then plugged it back in. I turned the keys, and wouldn't you know it, the car started right away. Now whenever I need to drive somewhere I perform my trick with the sparking screwdriver, plug the wire back in and I'm on my way. It never fails. I've started my car that way three times today. The distributor cap and wires are only a year old and they all seem to be in good shape. This is the strangest problem I've ever seen in my porsche. I figure it must be a computer problem. Does anyone else have any theories? Anyway to diagnose this mysterious problem? I'd appreciate anyone's opinion on the matter because although the sparking screwdriver makes for a good party trick, it's a bit embarrasing on dates.

londel · 08-10-2003, 02:38 PM

If I were to take a guess I would think the coil might be the problem. Do you have access to a used one or a friends that you could borrow before spending the money.

JonVaccaro · 08-10-2003, 02:57 PM

I thought that it might be the coil too, but itl is new. I checked it against another coil just to be sure and the resistances all came out the same. Then, just for fun, I put the other coil into my porsche and tried it out. It didn't help.

FLA944 · 08-10-2003, 06:22 PM

Jon,

I think you have an issue with ground.

Clean, inspect the grounds at the batt./ block/ firewall.

Rick

sixbanger · 08-10-2003, 08:53 PM

I'd check the fuel pump relay.I had one that when I hit a bump in the road it would die every time.I thought I had it fixed many times.Every time I did something I thought This is it.WRONG
I tracked it down to the relay one day.I opened it up and after a very close look I saw where a solder joint had cracked and had a black line where it burned and sometimes it would make the connection.I soldered it and never had the problem again.

SoCal Driver · SoCal Driver's Garage

What brand of spark plug wires did you use?

Remember that the spark trigger comes from the DME via the reference sensor. Also sparking the coil to ground to test it can blast the DME.

Smile · 08-11-2003, 02:59 AM

maybe the wire is broken?

CJFusco · CJFusco's Garage

i would think that the wire is faulty, but what do i know?

drew1 · 08-11-2003, 04:38 PM

IF your rotor button has that black thing between the coil terminal and plug wire terminal, check it with a magnifying glass for a hole. They can go bad kind of intermittenly.

drew1

marpos · 08-12-2003, 07:31 AM

Hi Jon,
I had the same problem, no spark to the coil. After analyzing the problem we saw that the DME relay wasn't getting enough voltage for whatever reason. I simply ran 12 volts from elsewhere to the DME relay via a small wire and that resolved the problem.

Tom