HELP: Porsche 944 no spark (2025 Update)

Is there a pulse at the injectors?

There is plenty of fuel in the rail. We haven't' checked the injectors yet because we were unable to get spark. So we wanted to solve that problem first. They are unrelated, right?

-Jon

Could be any of these, but I would try the DME relay first, this is the classic failure of these vehicles. I had a similar failure on my '88 and it ended up being a combination of bad coil and poor solder joints in the DME (likely caused by the bad coil overheating the coil driver) but if you are confident in your diagnosis of the coil as being good try the DME relay. You can bypass it temporarily, look for a procedure on Clark's Garage.

nate

Simple presence of 12 V at the coil does not guarantee a spark, if that helps any.

There are a number of different types of ignition circuits around, and I dont know what that Porsche uses...

So, if there is 12V there, can we rule out a bad DME or bad speed and reference sensors? asked another way: would a fault in the DME, or these 2 sensors cause no voltage at the coil?

When you try and start the engine, does it pulse? If not, it's not getting proper signal.

Makes sense. Coils fail occasionally, but not very often. And usually when coils fail, it's because they're not being driven correctly.

Okay, sounds good.

The coil is fine. One of these sensors is bad, or the ECU is bad. Pull the codes off the ECU and see what the ECU has to say.

There will almost always be 12V at the coil.

--scott

The spark is actually produced by taking away the 12v. The DMA will ground the coil for every time it needs to spark. You can try testing the coil by using Clark's website suggestion. I tried this and I thought I would see more of a spark. I actually had a hard time seeing the spark so I had to move the coil and battery into a dark room like a walk in closet to see it.

My guess is if your coil measures good it probably is good. Do you know about Clark's web site. Here is a link to the troubleshooting section on "No Spark":

No. Both the spark and the injectors are commanded by the ECU. If the ECU doesn't know that the crankshaft is turning, it won't fire either one.

If your coil were gone, you would not have spark, but you would still have plenty of fuel coming out of the injectors. But you'd have noticed this if it were the case because the exhaust would have smelled strongly of unburned fuel.

--scott

The ignition coil works by rapid collapse of the voltage in the primary coil. If the primary and secondary show propter resistance then the coil is probably OK. The sensors can only be tested with an oscilloscope. They may have slipped in position. You need to check this. Go to

And you should not.

If the engine is not cranking, there will be no spark.

If there is no spark when the engine cranks, suspect the ignition module, distributor pickup, or associated wiring.

DME relay

Try using a three-way jumper plug to replace it. This has 3 spade connectors, like the wide ones on the bottome of the relay, connected by two wires. Picture the old McDonalds "M".

D> Hi Group,

good work - do not discard the old sensor - believe it or not, I've repaired them - just find the break in the coil and fix it