The only timing issue it could be is skipped teeth on the cam belt. The ECU sets the spark timing. Valve timing doesn’t change once the cam belt is correctly setup. 

Cheers 

Bennie

On 10/27/2023 at 8:40 PM, ThosL said:

probably timing issues as the compression is tops.

 

On 10/26/2023 at 7:39 PM, ThosL said:

  However it's clear to me that bent or malfunctioning valves are the reason for the hesitation and sputtering on the other head. 
 

 

How did you change your mind so quickly?

The timing tensioner can fail. They’ll start moving around/bouncing vigorously during driving or cold start. 

If you take the cover off and watch it you’ll see it.  If it’s aftermarket or was compressed too quickly during reinstallation, that may have been its demise. Pull the drivers side cover and watch it at start up and when giving it throttle. 

6 hours ago, idosubaru said:

 

 

How did you change your mind so quickly?

The timing tensioner can fail. They’ll start moving around/bouncing vigorously during driving or cold start. 

If you take the cover off and watch it you’ll see it.  If it’s aftermarket or was compressed too quickly during reinstallation, that may have been its demise. Pull the drivers side cover and watch it at start up and when giving it throttle. 

To tell you the truth, I don't know what the issue is and I'm going to have the mechanic try to figure it out this week.   He went over the pulleys, etc. and only replaced what was needed.

7 hours ago, ThosL said:

To tell you the truth, I don't know what the issue is and I'm going to have the mechanic try to figure it out this week.   He went over the pulleys, etc. and only replaced what was needed.

Okay so your were just guessing?   Read all the codes check connectors removed during removal  

Prob bent valves. Hopefully you’re lucky and it’s the tensioner. Removing and compressing it for reinstall can compromise them.

The bent valve EJs I’ve repaired myself, it can be hard to tell if the valves are bent. Best to just replace them all than get fooled and leave a bent one there. They don’t always bend in a visually obvious way.

It is interesting if it’s true you’re saying you have good compression. The valve guide could be damaged or the valve is hanging in the guide, causing good compression but not fully opening. 

A quick leak check on the valves will tell you which ones are bent. As others have mentioned it is not unusual for all of them to be bent. Some will be obvious, some not so much. I have made this mistake myself, its no fun to pull the engine to replace the valves I missed the first time. As GD mentioned just replace them all.

The Subaru is running fine as is.  I'll have the mechanic check compression again, wouldn't that be enough to determine problem valves?

20 hours ago, ThosL said:

The Subaru is running fine as is.  I'll have the mechanic check compression again, wouldn't that be enough to determine problem valves?

Leak down test is a far better test in this case.

There are no performance issues at this point, the engine and car is running better than ever, there would be no point for tests.