I removed a sensor from the left rear (under the exhaust manifold) of my 1986 b230ft engine with M46 trans.

It was just below the coolant drain tap facing the trans. and had a lead with two wires white and red and a 17mm body.

My best guess from info from the archives would be its the crank sensor, but I can't be certain because the wire connected to the sensor was cut off and not attatched to anything.

My idle and run is fairly smooth, with very rare hesitation. Given that my engine runs ok would the addition of this mystery sensor improve its perfomance?

Thanks for any answers

My 78 240 had one of those and was supposed to be a means of checking timing. A pulse was generated by a magnetic stud passing by or a stud passing by the magnet portion screwed in. Anyway, it did not affect the engine, but was a diagnostic device for timing. Now, if I am wrong someone will correct me.

dick

I went to the parts counter at the dealership and they had no clue what it was or did. The Bosch part number was discontinued and the fact all the scematics available were very vage didn't help.

But the volvo guru mechanic came over and told me it was indeed a diagnostic sensor and that they don't affect the performance one bit, besides closing the hole for the sensor.

He also said that those units used to diagnose are all most likely in a landfill somewhere. Due to age and lack of need I asume.

So if anyone else runs across the same sensor, now you know.

v diddy