DME relay?
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From: Mystic, CT
DME relay?
While driving today both in 4th, 6th and 2nd gear, the engine went lifeless for a brief period, a second or so, then resumed. Does this sound like a DME relay issue? Thanks
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From: Houston, TX
When my DME relay went out on a drive back from LA to SF, it started as a small, intermittent hesitation that happened randomly over the course of a couple hours. Felt like the engine was starting to cut out but didn’t… until eventually it did about 5 minutes from the house. Replaced with the Focus9 solid state DME relay and no issues since.
Sounds like you’re noticing a pattern with gear changes which could be something else—unless it’s coincidental.
Sounds like you’re noticing a pattern with gear changes which could be something else—unless it’s coincidental.
Thread Starter
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From: Mystic, CT
I took the relay apart and found what appeared to be a suspect solder failure. Resoldered it and took a short then long (1hr ) test drive. No issues since the fix. Hoping I got it but ordering a spare to have on hand.
wesr your experience sounds similar to mine. Thx.
wesr your experience sounds similar to mine. Thx.
Last edited by CT Mike; Sep 24, 2022 at 03:24 PM.
Racer
Joined: Aug 2010
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DME relay is the only technical issue I've faced since my ownership. It's just bad design and always the first suspect when this kind of things happen.
For me the car just died temporarily and then started to jerk a lot under pressure. Changed the relay and sprayed electronic spray to the fuse box holes and no issues since.
For me the car just died temporarily and then started to jerk a lot under pressure. Changed the relay and sprayed electronic spray to the fuse box holes and no issues since.
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From: Charlotte, NC
This happened to me today on a drive to Cary, NC from Charlotte on old Rt 64. We pulled into a McDonalds along the way and when I came out, no start. My wife and our dog look at me like "are you kidding me, stuck here?) I have a spare DME relay (the original German one) and switched them out. The relay I took out was quite hot (is that normal?). Car started immediately and we finished our trip with no further issues. I had this happen once before with our '84 Carrera so I was aware of the symptoms.. Always carry a spare.
Last edited by rdad993; Sep 24, 2022 at 08:33 PM.
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From: Colorado
Hot is normal. It's part of the failure mechanism. This DME relay stuff is completely fixable. After the first time it failed on me, I went to the solid state relay and never looked back. One less thing to worry about.
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From: Dallas, TX
Hi Rdad,
Yes, it can get quite warm as the internal relays are in the actuated state with the engine running and their electromagnet coils produce heat. This is part of why it fails as temperature cycling and vibration eventually cause one of the solder joints to fail.
Andy
Yes, it can get quite warm as the internal relays are in the actuated state with the engine running and their electromagnet coils produce heat. This is part of why it fails as temperature cycling and vibration eventually cause one of the solder joints to fail.
Andy
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Former Vendor
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From: SoCal
Now with at least 5X the number of components versus the original DME relay, what's the failure rate versus a properly re-soldered original relay?
Last edited by systemsc; Sep 25, 2022 at 02:54 PM.
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From: Toronto & Mont Tremblant
Maybe someone can confirm - I was told the solder failures are due to the widespread ban on lead, however, Hungarian made DME's use leaded solder and are reliable. I bought 2 and have had no issues.
Last edited by ronnie993tt; Sep 25, 2022 at 04:35 PM.
RL Community Team
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From: Dallas, TX
Not sure your logic holds as the lead-free rosin core solder melts at a higher temperature and seems to have a higher tensile strength than led-containing solder..
When my first one failed it was the solder joint to the internal frame that holds the relays. When I resoldered it I added a few copper strands of wire to the joint. My thinking is that it adds strength.
In any event, I have only had one DME relay failure event in the 100K+ miles on my car so I can't see the benefit of paying a premium for the solid state version especially since my original, now fixed, sits in a door pocket at the ready.
There is an upside to buying the one made in Europe you mention in that it probably is the same design as the one being replaced. Purchasing one made in Asia most likely doesn't share the same design and may have a shorter service life.
Andy
Last edited by pp000830; Sep 25, 2022 at 05:39 PM.
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From: Colorado
Originally Posted by systemsc
Now with at least 5X the number of components versus the original DME relay, what's the failure rate versus a properly re-soldered original relay?
But let's stick with the original since it's super reliable.
Nordschleife Master
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From: Toronto & Mont Tremblant
Hey Andy. I have read there is no lead solder in modern cars. Not sure when it ended. Aircraft still have lead-based solder. Not a metallurgist but I'm thinkin' lead must be more reliable. As an aside, did you not used to be in NY? Ronnie
Former Vendor
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From: SoCal
besides a marginal original soldering process. Given the thermal mass of the relays used, a reliable soldering process requires properly heated relay pins before the solder application.
Many 964/993 owners always carry a spare relay.
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From: Colorado
I don't disagree with you, I just chose a different solution. To each their own.
Somewhat related, I don't put this all on a poor relay design. I don't have the data to prove it but I suspect as these cars age and the fuel pumps wear and draw more current, that the increased heat load contributes to the failures. Likely why we see these issues pop up after so many years.
Somewhat related, I don't put this all on a poor relay design. I don't have the data to prove it but I suspect as these cars age and the fuel pumps wear and draw more current, that the increased heat load contributes to the failures. Likely why we see these issues pop up after so many years.