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Checking reference and speed sensor when cranking


osc911

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Hi,

  Did it once , without a proper Break out box its seriously awkward. Also this method ,or a static test of resistance , may give a false result, as when running engine heat soak alters cable resistance/ volts.

The quickest and best method IMHO would suggest,remove NSR wheel and visually check the insulation on the sender cables.

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I haven't tried this, I haven't needed to but it seems like an easy quick way of testing them if the car won't start. The 'break out box' mentioned above is just the 35 pin ECU plug which is under the passenger seat on a 3.2 so easy enough to get to. Of course they may later break down with heat/vibration but a good starting point IMHO.

Chris.

 

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5 hours ago, Chris T said:

The 'break out box' mentioned above is just the 35 pin ECU plug which is under the passenger seat on a 3.2 so easy enough to get to. 

 

 

Unfortunately, no Chris. A Break out box is a special tool, which is plugged into the ECU cable. The top of box has series of holes, to allow easy multi meter connections.

http://forums.pelicanparts.com/porsche-911-technical-forum/33877-dme-breakout-box-where-can-i-get-one.html

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A break out box is indeed a different tool, but that is not what is being used in the You tube clip above where the guy is simply testing from pins on the ECU plug. However, if you wished to simulate a break out cable, you could remove the lid of the 35 pin ECU multi plug and connect your multi meter directly too the pins there or cut back the insulation on the appropriate wires exiting the plug to enable testing, then re-insulate of course.

Chris.

 

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Thanks all, I did end up checking mine looking over the car before the first start-up in many years! Both sensors as reported above, static and dynamic, and I have noted the comments about the insulation getting tired and performance degradation when heated. I will just change them at some point, but mine are good at the moment. 

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  • 4 years later...

The insulation on both my sensors on daisy over the engine has cracked and is falling to bits. Guessing this could be a cause of a rough idle at times and is causing the car to cut out when returning back to idle when warm and running. Restarts by dipping the clutch and bump starting. Another job 🤦‍♂️

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