In an effort to remedy a persistent P1396 error code, I finally broke down and removed the rocker covers to investigate hardware. A mechanic for previous owner couldn't fix it. and still charged $1,000+ for parts and labor, He did note possibly a noisy secondary chain at start up but chain tensioners had been upgraded. I found the metal secondary chain tensioners installed so that made me happy. I was very careful to double check cam timing (always idled great) and they're spot on. Both actuators snapped on & off just fine but I swapped them to see if the problem swaps banks.. The A bank solenoid showed about 7% less resistance than B so I'm crossing my fingers A starts acting up and B is happy. A bank 2nd chain is sloppy but B is tight. I pulled the exhaust cam to get the secondary tensioner out, but the spring action is fine.

I discovered why A bank is slack- there's no spring return in the actuator. Driver's side (US model) B cam snaps right back to fully retarded, but not A. Since both solenoids were removed and there's no oil in the system, I doubt that actuator is full of oil; rotating the cams should've cleared them out for the most part. I'm sure the oil pressure would easily overpower the spring but it would require more power to match the actuator with no spring load. I wouldn't be surprised if this is my issue. It is disturbing that B is getting blamed for the fault if this is the case.. I can experiment with adding a resistor to A solenoid to choke it down and match B closer. Maybe the higher resistance solenoid in A and lower resistance one on B bank will make the difference. I'm not anxious to tear into the front of the engine to swap out the actuator. Car runs great otherwise but the Check Engine Light is annoying.

They show two drain plugs in the bush carrier at the solenoid socket but they do not look removable. If I could extract one, I could spray some penetrating oil in and work the cam back & forth to see if it frees up. Maybe plug the oil feed and attach a hose where solenoid fits and pour some solvent in where it stand above the actuator, rotate cam to let it in and then have it set for a while.

Anybody have experience with these actuators, like they may bind up and not rotate properly?

 

After some research and more hands-on playtime, I'm pretty confident the actuators are healthy and the hardware looks fairly bulletproof.

The earlier "binary" actuators get a shot of oil at full oil pressure to advance fully, and then valve remains shut. These rely on a heavy spring to return to retarded timing.as the valve deenrgizes and drains the oil. Every 5 minutes or so, there's two of those mysterious clicks coming from the solenoids where they give a little squirt to lubricate the seals.

On this '99, "variable" actuators are fed a steady feed of oil at partial pressure to vary the amount of advance with position feedback from the cam sensors at the back of the engine. The partial pressure is adjusted via the ECM by pulsing the power, "Pulse Width Modulated, PWM," to the solenoid at 300hz, changing the length of the "on" pulse longer and shorter for higher and lower pressure. It works out to a closed loop servo system where the ECM can use the cam position sensor to adjust the pulse width for minor adjustment. There is a small drain through the beveled teeth in the actuator so the solenoid operates full time to balance oil feed with the drain to maintain control of pressure. The spring in these is very weak compared to the binary actuator, just strong enough to move the inner sleeve in the retarded direction with the engine off. The solenoid spool is normally up where oil circulates one direction to retard cam, then starts vibrating down, revering oil flow to advance the intake cam.. I like the idea that the oil circulates through the actuators so our detergent oil flushes them.

I went out and rolled the engine to different positions and it sure looks like the spring action of B bank was from a valve spring rather than the actuator spring. Live and learn.

Now, I can reinstall all the hardware, hook up the cell phone to the solenoids, and then, like the three blind mice, I can "see how they run!"