Understanding Camshaft Flank Angle - Enlightenment in Progress ECM 644A Topic is solved

[Maestrours]

Hi there,

I'm new here as I'm french and it's a PITA to find good threads on VolvoS in my country.
I'm fighting since a month and a lot of hours against a rough idle on a V70 XC 2.4t I just bought.
I've already changed spark plugs, injectors, oil, vacuum pipes and ETM (with hall sensor)...
After ecm-640A I changed my camshaft valve with a Skandix one. It immedialty partially solved the problem;

At start the engine runs great. As its hot, its inevitably lead to have the rough idle again. If I shut down the engine and starts it immediatly, it runs fine again, but not perfect, and the code ECM-644a appears (with no engine light), I have to connect an OBD reader (Vdash, I do not own VIda for the moment...). After some driving, rough idle come back, especially in traffic jam.

If I clear the code and restart the engine, it runs perfect again, until the rough idle and the code come back, (approx 5-15mn).

As I tested the valve and it seem ok (4.3ohms, clicks when 12v, new synthethic Oil), I guess I’m facing the same problem as you Abscate ?

As i’m french and speaking english not as fluent, I may have not understood how the VVT setting can be wrong.

The landmark on my timing belt seems good, but not the one for the tensionner (it is on the right of the right notch, even when engine is cold at 10°C (50°F).

Sorry to ask but do you think you can explain me « simply » how to check/set the timing belt and the VVT pulley, as I’m planning to do the timing belt with water pump ?

I own an Haynes manual in english that explain the timing belt operation but it don't mention this VVT set.

Thank you very much by advance, google translate do not translate very much this thread, and in french some parts do not make sense….

[jdeclue17]

I've been researching this on the forum for days trying to find a resolution so I hope I can find some help. I have replaced my timing belt, tensioner, idler...using a cam and crank locking tools. Now have codes 643a and 644a with my scanner saying my input camshaft adaption is 29.5 degrees and my output camshaft adaption is 32.07 degrees.

Can I simply remove the belt, move the vvt sprocket CW 3 teeth to get within spec? I was confused by @abscate post above on CW or CCW for a positive or negative cam position.
thanks!

[jdeclue17]

Quick update for those researching this in the future. I set crank to the TDC mark and used a front cam locking tool to lock the sprockets. Removed the timing belt. Carefully slid the front cam locking tool out to move each sprocket one tooth CCW and replaced the tool. placed the belt back and adjusted the tensioner. Turned the crank over two revolutions then started the vehicle. No codes present and both cams were now within the +-20 that the VVT can compensate for. intake was near zero and the exhaust cam was around 12. Restarted engine multiple times and zero codes ever returned. CCW retarted the positive angle value.

[nliutilitt]

so for my own clarity sake, newbie at this, Advanced timing is rotating the VVT hub clockwise, toward forward direction of the car. Retard timig is counter-clockwise, toward the back? And on datastream, +5 BTDC is Advanced, and -5 BTDC is Retarded?