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Registered
Join Date: Jan 2006
Location: Westchester, NY
Posts: 97
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HELP!! It won't start.
The engine on my 89 944S2 died on the track while I was doing 100 mph.
I have traced the problem to no spark. After replacing the DME relay, I found that the spark coil is getting 12 volts but nothing is coming out (verified by a spark tester on the output of the coil to the distributor.). Question: If one of the sensors or DME is bad, should I not still get voltage to the distributor if the coil is getting voltage? I have not checked for gas flow, but I do know that I have no spark and voltage to the distributor. David PS. At this time, I believe that my problem is a faulty spark coil. Last edited by dmilzoff; 10-16-2006 at 02:25 PM.. |
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10-16-2006, 01:57 PM
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There is an ignitition module between the ignition switch/DME and the coil. These are usually the problems with the 'S' models. Second is the single reference/speed sensor. The 'S' has only one while the other 944 models have two. Don't confuse the third unconnected sensor with the DME sensors.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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10-16-2006, 06:14 PM
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Hey David....
coil has two circuits in it. For a coil to work it has power on one side from the key switch and the DME cycling on the second circuit is what makes it send the spark. That's oversimplified, but hopefully it will make some sense. So, if a coil is getting power from the key doesn't mean the coil is going to send a spark...the DME has to be working it from the other circuit to make the spark happen. So, to answer your question...if the DME or one of it's inputs (including sensor) are not working properly, you will not get spark to the distributor. If I were you I would follow the advice of the post before me, SoCal really knows these cars well and he will not steer you wrong.
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Tom 1990 944S2 Cabriolet 2002 Chevy Silverado 2500HD 2003 Maroon Ford F350 dually Last edited by Razorback1980; 10-16-2006 at 08:05 PM.. |
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10-16-2006, 07:53 PM
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Registered
Join Date: Jan 2006
Location: Westchester, NY
Posts: 97
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Thanx for all for all of the help. I will be checking the Speed Sensor.
SoCal Driver: Where is the ignitition module you speak of and how can I test it? David |
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10-17-2006, 02:35 AM
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Follow the wires forward of the coil and you should find it mounted on the fender.
Looks like testing it involves looking for the control from the DME to one of it's pins. "Control" means the DME will usually ground a circuit. The ignition module is an interface between the DME and the high voltage of the coil. There should be battery level voltage on pin 4 of the module and pin 15 of the coil with the key on. Pin 5 on the module is the control signal. Proper testing involves using an oscillascope between pin 5 and pin 2 of the module and cranking the car. Note that the cable is connected to the module. The resistance values for the coil are 1 to 15; 0.4 to 0.6 ohms, 1 to 4; 5 to 7.2 k ohms.  
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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10-17-2006, 11:23 AM
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1983 Porsche 944 2.5 liter
