Sorry I couldn't post this sooner (yesterday) -- the board seemed to be 'out of order' until now.

Anyway, with much Thanks to everyone who's been helping me, regarding these earlier posts on my '84 B23F, LH2.0, I want to give you updates on my high HC (along with awful idling, no doubt related) problem:

1) First, probable good news: I checked my cat converter with heat measurements (a RayTek IR thermometer): on the pipe just a few inches in front of the cat, I was measuring about 460 deg F; but at the cat, it was "off scale", which for this model means over 750 deg F. I guess this means it's still working (reacting).

But more significantly, I got some surprising (and disappointing) results when I made a side-by-side comparison to one of my '93 240s.

2) First I did the "cylinder balance" test by pulling spark plug wires to see how the car reacted. I had originally done this on my '84, and the car's idle (equally for each cylinder) dropped very slightly, with just a little worsening in the idle roughness. I thought (and had reported optimistically) that this was a good sign, meaning that the cylinders were equal.

Well, yesterday after reading your suggestions, I did this on my good '93 as a comparison and was shocked! I saw dramatic (though equal) drops with each cylinder; and I have to say that in comparison, when I did this on my '84 again right aftterward, I realized that one might say that the '84, relatively speaking, hardly reacted at all during the test! So now it's appearing to me as if they all (equally) were barely firing at idle.

But you have to remember that the car pulls like a locomotive when I get on the road -- this is strictly at idle that it's running poorly (although emissions are bad at both idle and fast idle).

3) So I next rechecked my timing, and I was even more surprised. That 3 deg range of "wobble" that I recalled observing (when I did a tuneup a few weeks ago) has escalated (or become more noticeable?) into a ~12 deg range now: it's just bouncing very erratically back and fourth from about 1 deg late to 10 or 11 deg BTDC. And as I reported earlier, when I rev it up, although it becomes steady, the advance maxes out at about 30 (the left edge of the scale).

More, I decided on a whim to reconnect my vacuum hose to the Ignition Control Unit (NOx is no longer tested in NJ, so there was no reason to keep it blocked). Well, although I didn't see any improvement in idle, I noticed after the reconnect that my advance now maxes out at about 40 or more (interpolating beyond the "30" end of the scale); I retested a couple of times, and this seems to be a valid observation, at least measured while the car is stationary. Is this good or bad?

Anyway, it seems clear that my distributor, or the ignition control module (I really don't know which is more likely responsible) may be "crapping out". Could this explain all the high HC, and poor idle, that I have in this car? I'm sure its the cause of the lousy idle, after everything else I've tried, but the high HC also? Hmmm? Makes sense to everyone?

Looking forward to hearing from you guys, and if anyone has parted out their 240 and still has the distributor I need, or the ignition control module, please get in touch with me. Here are the details:

1984 (maybe 1983 also?) 240 (Bosch ignition system), B23F LH2.0 (non-turbo):

The distributor is marked on the side, 237-508-003, and it has the larger 14mm diameter shaft (that one the rotor slips onto; and not to be confused with a variety with a smaller shaft, ~9mm). It has to include the Hall sensor, of course, but it has the rectangular plug for the wiring harness (I think there's a variety with a round, cylindrical plug, or else an upgrade that was never done on my car).

The Ignition Control Unit, also original, is marked "1317295 USA". That's all the identifiable markings on it.

Thanks all, in advance.

P.S., I'm also going to post a separate message, just about the ignition control unit, to solicit from forum members who haven't been following this thread like all of you have. Please don't take offense -- No insult intended, but I have to plan on buying these replacement parts somehow, and I don't expect them to be readily available.