I had the car to dealer to check eratic idle suspecting a second ETM change. They cleaned ETM and claim that exhaust cam timing is out of spec and estimate $600 to repair. The estimate says; "ECM 644A cam control faulty position. Checked T belt markings ok. Cap adaptation opening 1- 1.23 OP 2- .083 OP 3- 2.02 OP 4- 1.41 Spec is 7". Any idea how to interpret this and what the problem is.?? I'm guessing something to do with the variable cam timing mecanism. I guess it requires special tools to make this check.?? Thks. G.

Hello G.,

The usual suspect for camshaft timing problems is the solenoid that actuates the variable timing pulley. This can be found by removing the plastic covers atop the engine. Just behind the exhaust cam pulley, you should see the solenoid (held in with four screws, has one connector, solenoid is around 4 inches long or so). Due to the small passages in the solenoid, any contaminants in your oil can clog the ports (such as, if the oil hasn't been changed regularly). You can sometimes clean them, which involves removal and disasembly of the solenoid (fairly easy, depending on comfort and skill level; let me know if you would like further instructions). The definite fix would be simply to replace the solenoid and gasket, but I wanted you to know that it is possible to clean the unit if you'd like. The solenoid itself is just shy of $100 (P/N 1275579), with the gasket being $3 or so (P/N 30731212). Anyway, thats likely what you need to do. If you do decide to replace it, change the oil at the same time. I hope this helps, and let me know if you need any more info.

Joe S. - Volvo Master Technician

2000 S70 AWD, 1981 242 Turbo w/intercooler

I removed the solenoid and blew through all of the orifices with compressed air and degreaser. It appears that to dismantle, I must unscrew the plunger where it meets the body..?? I put light force on it but afraid to break it without a replacement in hand. I put 12v through the connections but operation appears sporatic. Perhaps the problem is electrical..? I would be surprised if it is due to dirt as I change the oil and filter regularly. G.

Hello again,

You may be better off just replacing the unit. If you do decide to disassemble it, remove the bolt on the end (10mm I believe) and pull the guts out (it will pull hard due to the o-rings sealing the inside). Clean thoroughly with carb cleaner. Apply petroleum jelly to the o-rings before reinstalling. You also stated that you replaced the timing belt 3 months to this. I am assuming that the problem just now developed, not shortly after the belt change? As I said, the solenoid is the usual culprit, but I make no guarantees. I have never seen a problem in the hub itself. As you figured, the solenoid controls oil pressure to the hub. The hub then acts as a worm gear to vary the timing. Anyway, let me know what else you may need. I am happy to help.

Joe S. - Volvo Master Technician

2000 S70 AWD, 1981 242 Turbo w/intercooler

Joe.....you are the "Man".. The dealer mentioned replacing a solenoid and maybe the "hub"..?? I presume that the hub is actuated by oil pressure from the solenoid...but I'm asking questions without actually seeing inside yet. I will look on the weekend. I changed the t-belt about 3 mths ago and didn't take note of the mechanism. I will try cleaning the solenoid but how will I know if it is working..??..and how will I know if the hub is good or bad..?? I have built alot of race engines over the years but never worked on a variable type system. I'm more used to measuring overlap at TDC with a dial indicator and having that remain static during operation. I also now have the check engine warning light on. My OBD2 code reader can't seem to get a fault code. I don't know if it's from the cam timing or ETM that they cleaned. Thanks very much for your help Joe...much appreciated. Gary