When the engine is left to try and idle on it's own the wiper are doesn't settle into a relatively fixed position. It's so active as the engine is on the verge of dying, sweeping out large arc quickly, that I can't discern what a "natural" idle position would be. The engine does a lot of rapidly dying (wiper goes to almost closed) and resuscitating (wiper pops open) until it finally dies. The wiper's very still then. :|
Last compression was done sometime this summer. I can't find it in my records so I'm going off of memory. It was a solid 120-125 across all cylinders. I adjusted my valves just last week and didn't detect any changes in the point of contact of the adjuster screws with the valve stems.
Swapping out my AFM remains on my list, but that's a full re-tune of the other AFM. Not that it's the end of the world or a massive time commitment, just that I'd be introducing other variables if I get different, but still anomalous behavior. In theory, I should be able to pinpoint the issue with this current setup.
In further news...I'm spending the week experimenting with the mixture screw on drives to and from work to take advantage of the commute for a little testing. Started with the mixture screw at 4 1/2 turns out (what all the previously described symptoms are based off of) and backed it out 1/2 turn further for the drive in. Result: still had a bit of a bucking issue (didn't expect a change here) and no real change in idle, but it ran more or less the same, maybe a bit better, but nothing crystal clear. I arrived at work and adjusted it another 1/2 turn out and will see how that affects things on the way home. It's about a 16-17 mile drive (about 35 minutes w/traffic) and I'm judging differences upon arrival at whichever destination. I'm doing this based on the vague recollection that my mixture screw was previously way the heck out...much further than I would expect.
Lots of good suggestions and questions coming in. I hope I covered them all. My plan going forward at this point is:
- Continue trying to find the best (of the worst?) mixture screw setting on commutes to/from work and in the evenings if the opportunity presents itself.
- Over the course of the week, try and make up my mind about how best to address replacing my harness
- Perform a manually fixed position wiper-arm-nudging test at "idle"
- At the weekend, swap AFM, tune w/LM-2, and pray to whatever gods will listen.