Engine won’t lean out

[Ron]

Hi Ron - that’s exactly why this thing is throughly confusing me. It’s just not behaving normally as what you suggest was what I initially assumed. Something is messing with the mixtures so that’s why I’ve sent it in for someone to reset then start working through it. When it fouled the plugs it was running in closed loop perfectly the day before!!

Yeah, it's hard to say if it is something getting worse (~OK but finicky in the very beginning) and/or something new or ??.
I still have to say check the 2 pressures. Everything is based off of the Primary Pressure...just too many ratios reacting with too many variables, with little being linear, including the Control Pressure...
I'm not betting on it, but the example of a bad PPR o-ring could fit: The Control Pressure counteracts the plate that the CO screw adjusts. If the Primary Pressure is off, the Control Pressure will be off anywhere other than where it was set (at idle, warm). A flattened o-ring could cause that. And if it then had a smile/chunk come off of it the pressure would be off a lot... Others: The WUR could of taken a dive, trash in one of several places, etc. Checking BOTH could eliminate a lot of potential problems while pointing to others...

[Ron]

Ron the one other symptom I haven’t mentioned was that when it was tuned and went into closed loop particularly you often heard what could be described as a “clattering” noise that would come and go. I’m starting to wonder what out of adjustment valves might be contributing?

Was it doing that before you had trouble getting it into closed loop?

It would be odd for a non-pushrod engine to go from what I usually hear referred to as "clattering" to quiet (lifters running dry-lubrication). Maybe "ticking" or "pecking"? I'd have to head it. Anyway, the valves being too tight or loose will affect the burn. But it would be fairly consistent and doesn't fit all of the other symptoms well imo.
A compression check could shed some light on that, but there are other tests I would do first.

[Jonty]

It occurs mainly in closed loop but I think that is because it hunts slightly in closed loop and as the engines rpm goes up as it hunts you hear the definite clatter then it stops as the rpm goes down.

[Ron]

You didn't say when you first heard it?
VID?

[Jonty]

VID? I’ve heard it since I owned it (a few months).

[Ron]

Sorry, can you post a video for us?

[Jonty]

No sorry it’s in the shop.

[Ron]

Did it go away when cruising?

[Jonty]

I couldn’t hear it while driving. Was only really noticeable when in engine bay.

[Jonty]

The other odd thing Ron was that the dwell would never read above 45 unless you hit the wot switch or put a battery across the 02 lead and it went to 89. It would never as part of normal operation no matter how you adjusted the mixture sit anywhere between 45 and 100. It would often sit at 11 and when I didn’t have it turned it would swing between 44 and 34 but if you richen it it would go to 45 stay there (as opposed to swinging at say 55-45.