DME Relay, why not one?
 

ANOTHER DME relay thread! Sorry.

After, too many hours searching for someone else that tried this I have given up and started a new thread.

The short end of the story:
My '86 911 (generally stock) sat for a couple years (4+?) while I gathered the courage to rebuild the transmission.

Now that she is all better I had a tremendous time getting it started (i.e. might be replacing the starter soon) once started it only, well never mind, the point is I replaced the DME relay and she came alive! No sweat! Drove the piss out of the car for a couple days, (the more I drove it the more everything seemed to start working again, lights, gauges, funky smells dissipating, etc.) Then one day... no start, suspecting my URO (Chinese) relay; I got another one with the same result, ran like a champ for a few days then no start. (specifically, no spark, especially in the AM when it is a bit colder)

So my question is why are there two relays in one? Why not just fabricate a single relay? Once this ice storm from hell clears out and I can get to my garage I intend to make a jumper wire (harness) to bypass the relay (for the time when the DME relay fails somewhere other than my house), but I intend to put a switch on it, and if I have a switch on it why not a relay?
OH! To make sure my car isn't killing the chinese I was going to stick my ammeter on the jumper wires to determine the load of each system(Sears sells a fantastic DC clamp ammeter for ~$50). Anyone else done that? Any ideas what each load should draw?

Thanks for all the advice!

Andrew

Sounds like you are frying your relay. Maybe someone can chime in with what to test. If nothing else, if you know someone close by that has a 911, put your "bad" relay in their car and see if it starts. That would mean you have an intermittent problem rather than bad relays.

On that thought I pulled the relay then I pulled the guts.

http://forums.pelicanparts.com/uploa...1296606223.jpg

It is a known fact that I am pretty horrible at soldering, however this job is pretty despicable

None of the terminals look like they got hot and I wish I knew what this white powdery stuff is.

HA! It appears that one of the arms for the contacts is pretty badly bent....

Not that it will solve the problem, but the OEM relays are rated at 15 or 20 amps I beleive. I bought mine (2 in fact) rated at 30 amps; tougher, no doubt.

Sucess!
 

Turns out the arm that that makes the contact was bent so the electromagnet was engaging but not turning the circuit on.

so what did we learn?
Lesson 1: Don't buy crappy parts
Lesson 2: Don't buy crappy Chinese parts
Lesson 3: Don't buy crappy Chinese parts even if they are supposed to work with your car.

nesslar,
so you are using two relays?

One is a spare............... :)SmileWavy

I've never had good luck with URO parts....on my P-car or my Land Rover. Pure caca.

From memory, as I understand it the DME relay's terminals tend to fracture over time and use causing non-continuity.

I heard and seen people re-flow the terminals/contacts.

Question is with the non-continuity will that cause the relay to over heat, the usual symptoms of a failing relay.

over,

yes...the soldered contacts break easily over time due to age and vibration....MADE WORSE by Porsche's idiotic design of the terminals being oriented to plug-in sideways....leaving the relay BODY hanging in space ! ( picture in post #3, here, with the relay cover off). Therefore, there is a tremendous moment-arm leveraging of the circuit board.

Solution?....( or at least, "big-help"?)--> place a rubber block under the unsupported relay body such that you take the bending stress ( gravity) off the body and its plug-in connection.

Did this on mine,....!!

My DME Relay is changed out before it fails.

Doyle

Beautiful. That's really good stuff right there. Maybe add a little electrical tape to hold everything in place. For you, Wil and Doyle: http://forums.pelicanparts.com/support/smileys/wat6.gif