Ian

Well, this is where I'm at. I got the 6 bleed screws cleaned

... I will have the 9 manual pages on throttle balance procedure, emailed to me by Steve, on my website tomorrow....

I bridged the Throttle Position Switch by grounding all three wires, and set the idle to about 900. I don't have a precision tach, so I had to go by the cockpit gauge. I did this by adjusting the large screw between cyl. 3 and 4.

Ditto, this is what I did exactly.

I then tried to find the AFM bypass screw. I couldn't find any "screws" so I figured that the hex socketed screw must be it. It's something like a 6mm hex, right?

Yup, it's a 5mm hex tho...

Anyway, I hooked up a multimeter to pin 5 and ground. By the way, the way they made the map on the cover of the diagnostic connector is pure German insanity. You'd think you could just flip it over and it would show you the right pins.. nope. The map is shown as if the cover is still on the connector. So, you have to picture it as a mirror-image. The thing that helped me figure it out, is that where pin5 should be (the o2 sensor), there was no metal - blank connector. So, I figured it must be "mirrored".

BINGO! I figured this out by noting that the holes are not symetrical around center, and that the cap image was the reverse of the connector....

At any rate, the MM was showing essentially 0V (really, something like 50mV). No amount of hex wrench turning would change that. If I reconnected the TPS, it would show 12V.

The O2 sensor was replaced about 2 years ago (about 10K miles) when I got a new cat. I'd hate to think it was bad again.

You don't need the bridge to adjust CO, it is only for idle speed adjust, as it sets the ICV in a middle position. It may just be that you are too far out of range for the screw to do anything. Question is, too lean or rich? To find this out, you should read directly from the O2 sensor.

I tried to find the connector. I think I did. Under and to the back of the coolant res. was a round yellow "barrel" type connector - about 10-12mm in diameter. Is this the O2 sensor lead?

Probably. It should have 3 contacts. One half of the connector has two pins and a socket, other half is the reverse. The two contacts close (next to) each other are the heater signal = 12V and ground when the engine is running only. The contact "by itself" is the sensor output lead. In my car, the half of the connector that is attached to the sensor (follow the wires - they should go back under the firewall) has a PIN for the sensor ouput, and SOCKETS for the heater circuit.

Is there a better place to test its health?

No...

If I have to crack open the AFM, what's the best way to do this? It seems pretty sealed. Do I remove the connector socket (one of the 4 screws has some yellow anti-tamper paint on it)?

Not sure what you mean by removing the socket. I actually just used a 1" wide chisel and twisted it as I moved it around the cover to lever it up. It popped free without breaking, and I didn't have to cut any of the sealant. That's all you need to do.

The Split second MAF conversion is looking pretty good right now. The latest BMP catalog is showing it at about $850. That's a lot of money for 18 hp, tho. Its just a crapload cleaner design, and its so easily tunable.

Supposed to turn crappy tomorrow, so I might be done fiddling for the winter..

Whoa there... it seems daunting at first, but it will all come together and be clear. I wouldn't worry about the MAF. Get a reading directly from the O2 sensor lead to find if it is rich or lean. Then go from there. Email me directly and I will give you phone # and we can discuss if you want. SInce you are getting no oscillation, it is out of range one way or the other. COuld be a AFM out of wack, could be an air leak, could be FPR or injectors causing it to be too rich, or O2 sensor could be fried but I doubt it

Well, I finally got a grip. did some research, had some stimulating dialog with Rod, and now I pretty much know/understand the whole AFM/O2 sensor/CO screw thing.

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Now, if your mixture is way off, the screw won't do squat, and the meter will just stay pegged at 0 or 12 volts.

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