DME Relay - carry the spare.

[cabmandone]

Originally Posted by 88911coupe

Thanks Cabmando, I'll check the sensors. They are relatively new since I replaced them when I rebuilt the engine a couple of years ago. Should it be "safe" to drive around with the bypass installed for a few days, just to take the DME relay out of the system and eliminate it as a possible cause?

IDK that I would. I'd probably buy another DME relay since it's a good idea to have the spare and see if the one you have is faulty. It's safer to go that route than to have a fuel pump that could run all the time if you were to have an accident while driving.

Another reason to check connections. If you have had your arms in the engine compartment doing any work you could have bumped one of the sensor wires. I did that to my CHT sensor wire while removing my heat blower in the engine compartment. It looked like it was still connected but it wasn't.

[88911coupe]

I thought about that but i'm trying to completely rule out the DME since the new one could also be buggy. Its also, at least so far, very random. Thanks for the reply.

[gtc]

Did you open the old DME relay and see what was wrong?
Mine lasted 28 years, and only failed due to solder joints cracking. I reflowed the solder, and it works fine again.
I have seen a DME relay where the circuit board had snapped. I'm guessing it was due to someone trying to pry up the relay without unbolting it.

[cabmandone]

Originally Posted by 88911coupe

I thought about that but i'm trying to completely rule out the DME since the new one could also be buggy. Its also, at least so far, very random. Thanks for the reply.

Personally I wouldn't be too concerned with out of the box failures. I'm not saying it doesn't happen but to me, you just don't know if it was really the DME relay or if they also messed with other things. A loose wire in the connector for the DME Relay that was jarred while removing the relay or something along those lines. I'd probably contact someone at PP and ask them about failure rates of the different manufacturers. I'm sure they could provide some insight into how often a new one comes back defective. Once you've got that info make your decision from there.

I'd put the relay you have in the car and when it acts up take a spare plug and make sure you're not losing spark. Gremlins are a pain but if you follow a troubleshooting flow chart you can normally track them down.

BTW, I'd bet there's a member somewhere close who for a beer or two would come help you sort out your problem.

Good luck!

[88911coupe]

I pulled out the old one and found what appeared to be a missing chunk in the solder where it appears to have fallen out. I had one lying around (old but working) and it seemed to confirm the one I replaced was missing a section of solder. Thats what made me decide to order a new one...which, as stated before, seemed to work fine until I ran into the same no fire issue again. Once I grabbed it and moved it around a bit the car fired up fine and has several times since. Now I'm just trying to eliminate possible causes/variables. One being the DME relay.

[wwest]

I went through at least 2 NEW DME no-worky relays before opening one up and discovering the SLOPPY workmanship, turned out one of the others was the same base source, solder joints that hadn't been heated enough.

Opened the original and repaired it and it has worked for years now.

[patz]

URO relays blow donkey balls.

[TheSt|G]

Reflowed the original before failure, added a rubber bushing to its mount point to reduce future wear, and I keep a spare Porsche brand unit in the glovebox.

[88911coupe]

Ok this is odd, I just tried the 3 wire bypass trick last night to see if it works and when inserted I hear what I assume is the fuel pump coming on...and the key wasn't in the "run" position. Very odd.

[88911coupe]

I believe I answered my own question....found a great article regarding the DME relay specific to 944s but it points out that connecting 30, 87, 87b is recommended however the pump will run regardless of ignition position. To have it only run when in the "ON" position you connect 86, 87 and 87b, however this uses wires that are really too thin to carry the current, therefore he recommends using 30, 87, and 87b...just that you can't leave it in place.

[redturbo911]

Always keep an original spare in the glove box. You never know.

[howard freeman]

Originally Posted by patz

URO relays blow donkey balls.

Everything sold as URO is Chinese junk.

[princej]

mine just died, lasted 2 years.

if your URO is 2 years and older, carry a spare. i got lucky, mine died in driveway.

would not start. replaced with a spare, started right up.

[kkkarpuk]

A URO DME relay failure almost stranded me at a gas station. When I first bought my '87 I bought a new Kaehler DME relay and kept it in the glove box. Last night with a sudden crank but no start issue after getting gas, I installed the Kaehler and was on my way in 15 mins. I know I should have tested the relay to verify it was good before I needed it. Something I will always do going forward. Now to dissect that old URO relay...

[patz]

Give the URO the float test. They are crap. Dissect it if you want a laugh....then toss it. POS out the box.

[Mrdi]

Looking for a tutorial for replacing the DME relay.
Thanks

[sugarwood]

The DME relay on a 3.2 is under the driver's seat.
Slide seat to front and back to access the bolt and harness clip.

[sugarwood]

To remove it, first slide the seat back to loosen the nut. (10mm)
Then slide the seat forward to unplug the wiring harness from behind.

[Joe Bob]

It's a relay, it plugs into the DME box. Consider the new solid state one, it's a few bucks more.

[Mrdi]

Thanks, very helpful.