Re: CO adjustment and mixture experiences (archive)

Well, this is where I'm at. I got the 6 bleed screws cleaned and the intake reassembled. The bleed screws were progressively dirtier from cyl. 1 to 6. I wonder if this is because the clean air comes in by #1 and picks up oil and gunk as it goes through the plenum.

At any rate, they're all squeeky clean.

I put them back in, tightened them and then backed off 1 turn - as per earlier instructions.

I wanted to get CO set, so I let the car warm up.

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.

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?

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".

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.

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?

Is there a better place to test its health?

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)?

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..

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.

...

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.

...

Follow Ups:

Re: CO adjustment and mixture experiences Todd Kenyon 21:34 11/17/2001 (1)
- O2 sensor ian M635 UK 02:20 11/18/2001 (0)

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