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DME resistence Q?
The resistence on my DME is .5 ohm while Clarks-garage says it should be .1-.3 ohm is my DME bad?
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07-09-2008, 01:01 PM
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Location: London, UK
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Probably not as the resistance of the wires account usually for about 0.2 ohms
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07-09-2008, 02:23 PM
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Location: motown
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A little more information would be really helpfull in answering your question - what are you measuring, where are you measuring it and how are you measuring? two or three feet of wire can account for .5 ohms resistance. My ohm meter vs your ohm meter vs the next guys will probably be different by 5%.
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-John '94 968 Iris Blue '85.5 944 White - Rally Cross and wrenching practice '84 944 Gemini Grey (gone, but missed...) |
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07-09-2008, 05:17 PM
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Using the Clarks-garage method with 12 volts, the volt meter is a good one (I think) using the factory leads on the voltmeter.
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07-09-2008, 08:26 PM
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You still havn't answered the most important question - what are you testing? There are like 60 pins in the DME connector.
What proceedure in Clarks are you refering to? I can probabaly help. but I can't read your mind 
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-John '94 968 Iris Blue '85.5 944 White - Rally Cross and wrenching practice '84 944 Gemini Grey (gone, but missed...) |
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07-10-2008, 01:30 PM
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I am testing the DME fuel relay using the method outlined here. http://www.clarks-garage.com/pdf-manual/fuel-05.pdf
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07-11-2008, 12:32 PM
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OK - I see where you're at now. What you're checking the DME relay for resistance across the contacts when they are closed.
0.5 is on the high side, but shouldn't be anything to worry about. If one pair is reading differently than the other (i.e 30-87b gives 0.2ohms and 30-87 gives 0.5ohms) that would indicate that theres a bit more carbon buildup on the one set of contacts than the other. If they're both reading the same, them that's just variability in your meter. Every time the contacts open and close, there's a little bit of electrical arc between the contacts. This arc is hot enough to melt the iron and other metals out of the steel, but the carbon gets left behind. We're only talking about a few molecules here and there, but over several thousand cycles, the carbon can build up and cause more resistance. If the relay has been used for a while (if you don't know when or if it was ever replaced) you might want to go ahead and open it up to clean the contacts. Just use some very fine sandpaper or emory cloth (800 - 1200 grit) and sand off the inside face of the contacts untill they're nice and shiney. A new relay isn't too expensive; so you might want to carry a spare with you (I've got one in my glovebox).
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-John '94 968 Iris Blue '85.5 944 White - Rally Cross and wrenching practice '84 944 Gemini Grey (gone, but missed...) |
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07-11-2008, 01:08 PM
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Thanks, I got a new relay today and the car is running a little better but still shutters violently when taking off.
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07-11-2008, 10:04 PM
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