So, I managed to do a few things from my to-do list, now that the rain has stopped long enough for the dry spell to coincide with my availability.
This is just an update, I still have a long list of diagnostic tests to try.
WHEN IDLE IS LOW - checked at 750
- Check ported vacuum level at closed throttle: definitely more than 0 but less than enough to register 1.
- Pull plug wires one at a time at idle to verify that idle decreases: just like at higher idle, barely perceptible.
- Manually activate EGR, see if it stalls: just like before, almost stalls but keeps running. Maybe a little closer to stalling.
GENERAL TO-DO DONE
- Disconnect vacuum advance entirely and test-drive: actually I did this one before today. Bucking/skipping is pretty darn bad when hooked up this way. Idle is almost decently low.
- Disconnect a vacuum hose at low and high idles to see if RPM goes up or down from intentional vacuum leak: no noticeable change in RPM
- Hooked up vacuum gauge to EGR vacuum line from TVS: acts like ported (zero at closed throttle, comes alive with throttle open) but reads slightly closer to dead-on 0 at closed throttle.
- Hooked EGR to manifold vacuum (and left gauge hooked up to EGR's previous TVS vacuum). Idle is 1100. I'll see how it drives (and what the vacuum gauge looks like).
- Look at the vacuum gauge while I unplug a wire so I can get familiar with a steady single cylinder misfire: Ok, it's a quick steady shake.
I also hooked up a spark tester
. All cylinders look the same. For comparison I tried it on my 2002 GM V8 (and broke one of its wires). The 2002 lights it up brighter. I don't know if I should expect as strong of a spark from the Buick but I guess I'm not getting it.