I am chasing a strange tick which comes and goes so can I unplug the VVT solenoid and run the engine?

 

Yes, you can start the motor with the VVT solenoids disconnected, but keep the revs fairly low. You may get some P139x codes thrown & MIL.

I read somewhere that the ECM 'exercises' the VVT units periodically at idle (I can't remember exactly how frequently, but it is minutes.) and they will give intermittent clicks while doing this. I'll see if I can find the source.

The injectors also tick, but I guess what you're hearing is louder than that?

 

Very useful so thanks .If you find out how often let me know

 

Ticking sound that comes and goes (say, a min on, a min off) can also be coming from the purge valve. It is located in the left front wheel well, behind the liner. From memory, there is a TSB involving a long gone sound "blanket" to wrap the valve in.

Best of luck, keep us posted.

 

From the 'Engine Repair Course 168':

"
While the valve timing is in the retarded mode, the ECM produces a periodic lubrication pulse. This pulse momentarily energises the valve timing solenoids to allow a spurt of oil into the valve timing units. The lubrication pulse occurs once every 5 minutes.

NOTE: With the vehicle stationary and the hood open, operation of the valve timing solenoids may be audible when the lubrication pulse occurs at idle speed.
"

So, once every 5 minutes is probably not your issue.

I keep forgetting about the purge valve that fmertz suggests

 

The noise comes from the right hand valve cover area towards the rear so I think the purge valve is out the picture . The valve clearances are spot on and a metal chain tensioner is fitted with new chains about 30K ago. Just sounds like a noisy tappet ( there is no item in any car called a tappet !!) The search continues.