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Who does this?? When I find them... (resistor in Head Temp Sensor line)
After months of checking every knowing circuit, Fuel, Spark, Mass Airflow, Oscilloscope to it all and nothing, we went back to the most likely source, the Head Temp Sensor (symptoms: starts fine but within a minute is surging and then floods and can't restart for a couple hours). From terminal 13 at the DME to ground it was an open circuit. testing only beyond the connection in the engine compartment the resistance was in spec. We peeled back the rubber cover to the white clip and see a broken wire with a resistor attached to one wire! The hardest problems to fix are those created by someone else. Jumped the wire and it purrs like a tiger. Will replace the connector and wire tomorrow!!!!
The added resistor (5.6K ohms) resulted in about 3X the normal (2K-3K ohms) resistance when cold, and over 10X the normal resistance when hot. The normal hot resistance is less than 300 ohms.
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Loren
Systems Consulting - Automotive Electronics
Specializing in Porsche cars http://www.systemsc.com/
Can you explain what the purpose would be of doing this? I assume they were trying to fool the DME into either leaning out our enrichening the mixture.
Can you explain what the purpose would be of doing this? I assume they were trying to fool the DME into either leaning out our enrichening the mixture.
Yes, they probably had injector problems (stuck) and thought they could temporarily fix the problem by enriching the mixture.
10-01-2022, 08:46 PM
