Engine Cuts out

[supchg911]

I have experienced for the first time this year that my '89 911 3.2L, after driving the car for 10 or 15 minutes, shuts off and the dash lights come on. After attempting to start it a couple of times, it finally starts and there is no problem thereafter. This doesn't occur every time I drive it and haven't figured out any situation that consistently makes this happen. This morning after a 15 minute drive cruising at around 40 mph, the engine just turned off. I coasted to the side of the road and after 3 tries it started up and away I went. Thank God for good batteries! Any thoughts on what the issue could be??

[gtc]

I'm assuming you tried swapping the DME relay?

[supchg911]

No I haven't. That's a great idea though. And pretty cheap too! Ill give it a try and let you know.

[Fly911]

I had the same problem with my '87 Carrera, and it turned out to be the rpm sensor. I changed the rpm and tdc sensors (identical sensors), and also the cylinder head sensor, while I was in there...
I also have permanently installed two DME relays under the driver's seat, so I can swap the connector from one to the other in a matter of seconds.

[supchg911]

Thanks for your input too. I have just ordered a DME relay and will try that first, then move on to the next suggestion.

[Tremelune]

Test the DME relay, and if it's bad, replace it with a solid state one. It's unlikely to ever go bad again.

That doesn't sound like the DME relay, though. Relays don't tend to kind-of fail or get flaky over time. Next time you're stranded, you can use a jumper in place of the relay.

Intermittent issues are irritating...It could be as simple and annoying as a bad ground anywhere in the system. Does the fuel pump run? Is your ignition module too hot to touch? Are the wires to your coils about to snap?

[supchg911]

Those are great questions that I don't yet have answers to. I'm confused about the question about the ignition module. Are you asking if the key ignition is hot? I'll check that too. Thanks for the link that you attached about testing the DME too.

[Tremelune]

The ignition modules (you'll have two) are in your engine bay wired to your coils. This is unlikely to be your problem, but because it very recently was mine, it was on the tip of my tongue.

When the car dies you need to figure out if it's fuel or spark related. Tough to do on the side of the road, but it will break the issue down substantially. Hopefully that new DME relay will do it.

[supchg911]

So after getting quick delivery of my new DME Relay from Pelican Parts, I was able to put it in pretty easily. The next step was to take it for a spin. After reaching warm up and about 10 miles, I experienced no cut out. Turning off the engine and then back on a couple of times gave me no problems. Since the cut out was previously an intermittent problem, I'm not 100% sold that the gremlin is gone...but its a great start!
Thanks everyone for the feedback.

[pmax]

Originally Posted by supchg911

So after getting quick delivery of my new DME Relay from Pelican Parts, I was able to put it in pretty easily. The next step was to take it for a spin. After reaching warm up and about 10 miles, I experienced no cut out. Turning off the engine and then back on a couple of times gave me no problems. Since the cut out was previously an intermittent problem, I'm not 100% sold that the gremlin is gone...but its a great start!
Thanks everyone for the feedback.

Awesome.

The 3.2 Motronic is nice. Being the first of the modern ECU controlled FI systems, it remained relatively simple compared to the later ones and is far more reliable than the previous FI contraption used in the 911s.

[gomezoneill]

Not to rain on your parade but my bet is the rpm reference sensor and/or the tdc reference sensor (always replaced in pairs) are going. They are almost always a intermittent problem.