Daughter driving so I do not have all the details. Came back with it running poorly. Next morning would not start. Found all cylinder compression at 10-20 PSI except #3 at 40 PSI (chain cam drive so not likely jumped timing). 160K miles.
Put oil in the cylinders, compression came back to 140 PSI in all cylinders. Has misfire on #1,2,4, random and primary coil B P0352. Swapped coils misfire changed to #1,2,3. No rearranging of coils gave consistent cylinder # misfire except #1&2. No unusual noises other than rough running.
Put in new iridium plugs, no change. Eventually changed all the coils, plugs (gaped to 0.028"), injectors, cleaned throttle valve, replaced MAF sensor, Now misfire on #1,2, and random along with the permanent codes misfire #1,2,3,random, P0352. Checked all the fuses, pulled and replaced. Checked signal to #1 coil on oscilloscope, consistent pulse.
Changing the plugs again, found #1 & #2 plugs clean but the rest sooty which does not make sense.
When started cold, it runs at 1500 RPM with a trace of misfire but when the RPM comes down to idle it gets rough and triggers the check engine light.
Have run out of things to change or check. Any suggestions?
Thanks.

 

Took it to an independent shop. Apparently, the air-oil separator can cause misfires. Supposed to be replaced every 100K miles. Trying that. Search on misfires did not bring up the separator but searching the separator says causes misfires.

 

Well, for $270 they did a five minute oil mist test and said it was the air-oil separator. Changed it and now have misfires on cylinders 1,2,3,4,5,6 and random. Went back to the independent shop Foreign Sports and now they say that is the first of things to replace. I thought paying to have a diagnosis was everything, not try that and come back and pay more.
Pulled the cap off the original separator and found the diaphram has a split.


You realize that Ford could have just made this small diaphram replaceable instead of the whole box for a lot less than the $200+ that Volvo sells it for.
Checking the replacement separator (PPS) from AutohauzAZ, air flows both ways through the port. I have to check with them to see if that is correct. The very light spring under the diaphram holds it up off the port. there is a small hole in the cap. Presumably, when the outside air pressure is greater than the crankcase pressure the valve will close. Not the usual PCV that I am used to.

 

have you tried cleaning the intake air tubing and the MAF sensor? thinking if the PCV failed and oil misted the intake port, that would dirty up the MAF. Just make sure you use MAF cleaner not carb cleaner.

 

Thanks. I replaced the MAF and cleaned the throttle body. The MAF is next to the air filter which is far upstream of the throttle body. I do not know where the crank case vapors are fed into the intake stream but it must be downstream of the throttle body.
This air-oil separator is just a still air box with a long narrow tunnel leading to the diaphram port. Without the box on the engine there is a strong pull of air through a hole into the cam chain case. If the problem is that the engine cannot pull enough vacuum to close the port and causing too much air going into the intake, I can try plugging the port and see if that fixes the problem. I can use the old separator and put a plug in the port.

 

Plugging the port on the old separator and putting it back on made the engine idle better but still has the codes misfire on cylinders 1,2 4,5,6 and random.