yet another "rough running" thread
Hi, all!
We have yet another "the engine is running rough" story to contribute. We have to say that after reading some of the horror stories folks have lived we feel not so bad :-) but we really want to get this nailed. Our 912ULS is about 8 years old with 1200 hours, and we've put on 1100+ of those in the last 7+ (wow!) years.
The carbs balance wonderfully, but we haven't torn everything apart looking for intake leaks, so we can't rule them out. They've generally been good, the last time Lockwood serviced them they got a few new pieces and clean bills of health, and they aren't yet due for the next 200hr pass. We did weigh the floats, and we're well within tolerance. We tried the "choke test" and in general things seem fine; we couldn't spot any particular setting as way too lean or rich. The stumbling is most noticeable in the midrange like the low 3000s, we'd say.
We've eliminated the stator by swapping the red wires around, and we've eliminated the ignition modules by swapping the "after" MOLEX connectors. That should put us at the "A" wires & plugs, which is 1 & 2 top and 3 & 4 bottom. Unfortunately, the plugs don't look noticeably different compared to their friends; there isn't one that stands out.as an obvious problem. The boots are all happy & flexible and well-attached to the ignition wires so far as we can tell. Soooo ... we dig. Our next step, tomorrow morning, will be to sequentially disconnect each plug and see if the mag check is the same kind of unhappy, figuring that if it is then that's the plug that isn't pulling its weight.
At this point, we think we'll need to dig into resistance checking. We have the numbers from the MMH, but ... how do we check a given plug wire (in the boot, or pop it and poke the wire directly? and what about on the other end?) to confirm that it's good, and what measures (such as trimming back the wire and putting the boot on fresh, we read somewhere) should we take if it looks bad? We're really hoping to not have to pull the coils pack and everything else, but it kinda feels like that's in our future :-/
Thanks in advance for any advice and direction!
D
