camshaft position sensor 2.5LV6

[cc]

Once the alternator was back in, the engine cranked over on the starter motor but wouldnt fire. A check of the ecu was the next step for any digital trouble codes and Baz Baz came over with the lap top, multiecuscan s/ware and a wireless interface. Thanks Baz. Happily a camshaft sensor issue was identified.  After clearing the code from the ecu, the engine would start but with a very uneven idle. I knew the pin end of the sensor cable was in v poor condition as the blue insulation block the cable is embedded in had cracked and was v fragile. After removing from the engine the last of the blue plastic fell away.See pic of the old plug on the left with no! insulation and the replacement on the right. Interestingly there was a film of grey v v v fine metal on the sensor that sits next to the end of the camshaft on the rear bank.

A friends brother found the same grey deposit on the camshaft sensor of his moto guzzi, which was also misfiring. After he cleaned the metal off the bikes sensor, no more misfire..

A 2nd hand replacement sensor was picked up from Atwins in Sydney for $45. Thats the one in the pics.. It wasnt identical to the original sensor. But looks the same as the one for sale at the alfaworkshop in the UK. It came off an engine with 50,000km. The Bosch part number on the back is also different, and was also different to the part no in Eper.  A new sensor will cost $88 landed from the alfaworkshop UK or approx $230 from a Brisbane non dealer alfa workshop.

Come the magic moment tho it worked! with an even idle. A tackety hydraulic lifter quietened down and went away after the car came up to 90 deg and the twin fans came on.
However, it wont start if warmed up! left overnight it will then start.

Part numbers are;
Original in the car?
Bosch No 0232 103 024
Germany 187
Off an unknown engine from Atwins
0232 103 009
Germany 087

Eper number: 60586655 or 60816861
product code 46811123

[bazzbazz]

If wont start when warmed up its most likely Crankshaft Sensor

[cc]

The crank angle sensor is < 2 years old. The wiring harness that it connects to looks a little tired. Wonder how to test the electrical conductivity.. The car started happily again this morning, then wouldnt start again! The engine fault light isnt permanently on, which is an improvement. So i dont know as yet for sure if a d.t.c. stored in the ecu is preventing the car from running..
Have ordered a chinese wireless obd2 interface off ebay, see pic, hopefully arriving monday. To enable ecumultiscan thats been on the lap top for a while.

[johnl]

A marginal crank sensor may work when its temperature is less than X°, but not work when its temperature is more than X°. It can be like an on / off switch. When the engine is switched off the sensor is likely to (will) get at least somewhat hotter because of heat soak from the engine metal...

The engine metal unevenly accumulates heat that is constantly carried away by the coolant, but when the engine is switched off the coolant stops flowing (mostly, ignoring the thermo-syphon effect, which is relatively small). So, since some areas of the engine metal is inherently hotter than other parts of the metal, the cooler parts of the engine, and the coolant that is in the water jacket, then get hotter after shut down as the differing temperatures within the engine equalise (i.e. hotter parts get cooler, and cooler parts gets hotter).

Since the sensor is attached to an area of the engine casting that operates at a cooler ° than other parts while the engine is running, the sensor ° will increase (at least somewhat) after shut down. Quite possibly enough to tip it over the edge into not working.

Sensors can degrade with heat / time, whether the heat comes from soak directly from the engine, or from being exposed to radiant heat from the exhaust. Some Saab engines have the crank sensor located not far from the turbocharger, and even though Saab fits a little steel sheet heat shield this proximity causes these sensors to fail relatively often. The crank sensor on our Saab cooked (probably by the turbo) shortly after we bought it, and a second hand replacement not long after. I made an improved heat shield, double layer aluminium packed with fibreglass insulation between the layers, the new cheap Ebay sourced sensor has been fine for ages now...

Regards,
John.

[cc]

It may be temp related. The engine isnt warm tho when turned off and it fails to start again ..