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175mph951 175mph951 is offline
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Join Date: Sep 2005
Location: new york
Posts: 1,372
Quote:
Originally Posted by DCinVA View Post
+1 on the speed and reference sensors. I believe the bentley specifies a resistance test for these components. In this case it sounds like you have a failure when the engine is warm, but it works ok when it is cold. I suggest you test both sensors cold, and then again when hot.
the sensors are a square wave signal there for they are either on or off.....if a sensor is going bad and working intermitantly its because its loosing the magnativity(if thats a word) in its permenent magnet...in a hot/cold situation its becasue the aluminum bracket that holds them is expanding from the heat and there is not enough magnatism to make up for the change in distance. this can not be tested by the resistance. if you believe this is the problem they would have to be replaced with known good ones to test problem. if they are original from 1986 i would change them regardless just to prevent future problems. you can replace them with bmw sensors from early 80's 5series cars.....they are 1/3rd the price of porsche sensors and work the same....only difference is the length in the cable which works fine.
Old 01-02-2009, 12:09 PM
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