Ok so this is proving to stump a lot of Alfa specialists... Maybe someone can shed some light.
I have a 159 with the 3.2 JTS engine and have an issue with the variable valve timing (VVT) not working.
When the engine is cold the VVT does not work, meaning under load the valve timing does not change and the engine lacks power. Once the engine oil temp gets up to operating temp it works fine and engine has full power across the rev/load range.
This happens 100% of the time - doesn't work cold, works hot.
The ECU shows a P0016 error (Phaser exhaust sync error bank 1/sensor A). It is always this code that comes up. I have had occasionally a P0105 error but I think that is a result of the camshafts not working properly. I no longer am getting the P0105 though, just the P0016.
Something very interesting is that when the car is almost at full operating temperature and the VVT is working it will sometimes stop working. When this happens, while I am driving, I put the car in neutral and let the engine idle for 6 or more seconds and then put it in gear and continue driving - the VVT will then start working again – every time.
The problem started 6 months ago and it does it 100% of the time when cold – VVT does not work. In the beginning it would start working when the oil reached 70degrees C but now the oil temp pretty much has to be full operating temp (around 100 degrees) before it works consistently. Currently car has 130,000 kms / 80,000 miles.
In the beginning I thought it was an oil issue as one oil change I left the oil in for 15k miles instead of the normal 6k miles. So I had all the four solenoids removed and cleaned. The mechanic said they looked clean and seemed in good working order. Although it still may be a possibility one is faulty. I was using a 5w-40 fully synthetic oil, now I am using 0w40 fully synthetic (and I stick with the proper PAO/Esther oils). Since this issue I have also been doing an oil flush with the oil changes, but the problem has not abated.
Another thing I read is that there is a locking pin that stops the VVT working on start up. This is because there is no oil pressure and the locking pins stop the cams from moving uncontrollably at start-up. Once the oil pressure is up the pins release and the VVT works. It almost feels like this pin is getting stuck (at least on one or more cams) – but that is my layman’s guess.
I have contacted a number of Alfa specialists here in Australia and even quite a few in the UK - none have heard of this kind of issue. Some suspected a stretched chain but realized that it likely would be an issue at all temps not just cold. Edward at Edward labinjoh
has been quite helpful and has seemed the most knowledgeable on the subject but he's still looking into it.
Any ideas/thoughts would be greatly appreciated.