No Voltage from Sensor
 

Hello everybody, I ended up getting a rebuilt head and replaced the head, head gasket, timing belt and balance shaft belts along with some hoses and plugs. The started right up and ran great for a day till the DME relay went out. Replaced it and was running great again till a few nights ago. I was shifting to 3rd gear and the car just died. I'm getting no tach bounce and no spark. I checked the sensors and on pin 8 and 27 I was getting no voltage so I bought another sensor and thought it would fix my problem but no. What would cause the sensor ohms reading to be good but no voltage coming back from the sensor. As i understand it the reference sensor should get a voltage reading above 1 and the speed sensor below? Is this correct. Thanks for any suggestions.

You need oscilloscope to see sensor waveforms.

https://farm5.staticflickr.com/4616/...bff0f032_o.gif

What spacing did you set for each sensor? Included figure-8 washer?

I put a .8 washer on the end of an old sensor and used the speed sensor slot to set the bracket. As per instructions on Clarks web site. So with a volt/ohm meter connected to the correct pins, I won't get a voltage reading as I turn the car over. I worked all day and still no start or tach bounce.

Is this a turbo or NA car?

Or these:

http://forums.pelicanparts.com/uploa...1547389686.jpg

Did you look for AC volts?

The car is an NA. I just tried looking at DC volts. I don't have a second computer to check it out. If the sensors were not working correctly the computer would not send a signal for fuel or spark correct.

You need to look for AC volts at the speed or reference sensor to see anything.
https://www.youtube.com/watch?v=zeFOOcLSk60

Did you get both sensors to 0.8mm spacing?
Also test resistance between sensor-plug terminal and terminal at DME connector. Bad cracked wiring is common and people replace speed/ref sensors needlessly because of bad wiring.

- test resistance end-to-end of signal wire
- test resistance end-to-end of ground wire
- test resistance between signal-terminal and ground-terminal

https://farm5.staticflickr.com/4842/...147b20de_z.jpg

You can trim off wiring just before corroded/cracked section and replace terminals and connectors with new parts listed here: http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/878135-diy-harness-connectors.html

Thanks for the help, I will take your suggestions and try them out tomorrow and let you know. I know I only did the spacing on the reference sensor. When the car stopped on me going into third gear as I pulled over I though I smelled burning plastic as in a burnt wire but have been trying to trace it down with no such luck. I have checked for continuity between the sensor harness and DME computer but all seems ok?