Porsche Repair: 944 non- turbo intermittent starting problem., prosche, descrition

Question
Hi Dave, I have a 1987 non-turbo 944 Prosche, I've had the car about 6 months and I have not had any engine problems with it until now. Recently, I've had trouble starting the car, it will turn over, but it will not start, but if I go back to it later it will start like there was nothing wrong. The battery is fully chagred the plugs and wires look fairly new but not sure. When the car starts it does not seem to have any other problems. I have tried to check the coil and could not get a reading on the secondary side, meaning the meter showed no change when attached to terminals 1 and 4. It is just my thought that if the coil was bad it would not start at all or not run right when it was running. If you could give me some help I would greatly appreciate it. Thanks.

Answer
Hi Keith,

There are so many possibilities!  Given your descrition and your newness to the car I would suspect there is a wire or wires that are loose or corroded or barely making a connection.  When the moons are aligned properly and the temperature is right and you slam the door just so, the wires will act as if they are connected...but...if anything disturbs their condition, they will act up.

I realize the battery is fully charged, let's say 12.8 volts...but if you take a reading at the main wire from the battery to the alternator at the alternator do you get that identical reading?  What if you jostle the wire?  At this point, the plugs and their wires are probably good because the car will run sometimes...so I'd do this check with the battery and then make very sure the battery ground wire is perfectly attached as well.  One check would be to test continuity between the battery's negative terminal and the body part the wire is attached to.  The reading should show perfect continuity.  That level of "good groundness" should be identical on the engine as well.

I don't like what you're finding with the coil, but there is a trick on the 944's:  perhaps you know it already with your reference to terminal "4".  Remember the setting for primary resistance should be on a low scale and for secondary resistance it should be on a high scale.  I don't really suspect the coil but I sure would undo and re-do every electrical connection anywhere close to it to ensure for yourself that all connections are tight and valid...and thus rule them out as possible no-start causes.

Write back with what you find.

Dave