Hi

Water pump and cambelt were changed on this car a couple of months ago by another garage. After collecting it the owner complained of dead spot around 4000 rpm but no eml on. They relooked at it and replaced cam sensor after seeing p0340 logged. Car was no better and vauxhall dealer suggested changing cam sensor for oe part.still no better. Car deliverd to us with eml on, code p0340 cam sensor incorrect signal flagged.

Removed timing cover checked crank pulley keyway and retensioned belt.dtc returned when cranking.scoped cam sensor found some hash on signal then lost signal for a couple of minutes until restart. Replaced non oe!!cam sensor for another make (oe part not available for 2 days)and replaced crank sensor also. scoped signal no hash looked fine, but dtc returns occasionally on cranking.

Cam sensor is hall effect but cam sprocket does not have 4 lugs rather 2 raised semi circles that the sensor must pick up on. I dont see how it can differentiate between cylinders if all the hall effect signals are the same. I would like to synchronise the crank/cam signals on a fluke scope but am not sure how to or how to interpret what i get.

Disconnecting the cam sensor when running does not flag a code it only seems to happen when cranking and it does not start immediately.

Any advice gratefully received

cheers Paul