Hi Darrell

Welcome back to 87 hesitation continues where we are making "No Progress" one step at a time. Thanks for all that great data here are my results. I have a Bosch ECU # 0 261 200 065 (810) DF VW # 025 906 022 >From disconnected 02 sensor cable (green coax) to ECU 20k ohms With the ECU disconnected it measures infinity. (No short to ground) You wrote: "My coax wire / ECU pin 2 measures about 0.5 volts" I am getting with ignition on 0.06 volts with meter set at 1 volt scale and 0.02 volts with meter set at 0.25 scale (I do not understand this myself) Are you sure you read 0.5 volts or is it 0.05 volts. In the other test: Touch coax wire to ground / feed 1.5 volts to the ECU. I am getting the results you are referring to but you did not mention anything about the "time" it takes the ECU to change the air / fuel mixture (keep in mind I am monitoring the air / fuel mixture with volt meter hooked up to disconnected 02 sensor) it seems to me it takes about 5 seconds to change in either direction. Does that sound right?

Thanks again

Kai 87.2 Westy

Original message

Hi Kai,

The coax wire has been found shorted to ground by several on the list lately. It goes from digifant ECU pin 2 to the oxygen sensor connector, from this connector to the black wire on the oxygen sensor. My coax wire / ECU pin 2 measures about 0.5 volts with the oxygen sensor disconnected. This wire measures 182k ohms resistance to ground wit a vw ECU and 220k with a bosch ECU plugged to digifant cable. With the ecu disconnected it measures infinite. One of these checks should net you a pretty good clue to your problem. Best of luck to you and your van.

Darrell

Ps. Another test of the ECU and oxygen sensor wire is to start the van with the oxygen sensor disconnected and let it idle for a couple of minutes. Then touch the wire going to the ECU to ground, the engine will start running rich. If you touch it to a 1.5 volt battery plus that has the minus side on ground the van should start running lean. Something here should not leave you clueless.

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