kahlveen

Hi Guys. I just attempted to adjust my CO level as described in the 944 turbo workshop manual and am a bit confused by what I'm seeing on my AFM. From what I understand, if the setting has never been adjusted since the factory, there will be a plastic (or is it metal?) plug (p/n 944 606 935 01) covering the adjustment screw. It doesn't look like there is a plug on mine since the pictures in the workshop manual show the plug being flush with the AFM surface and whatever is in mine is pushed further down into the hole. I figured if the plug was gone I'd be able to make the adjustment, but I definitely don't see anything like a screw. What's there is metal piece with concave surface and a hole in the center. Have a look at the pictures. Has anyone seeing something similar to this? Is this the plug that someone removed once and pushed down too far when replacing? I tried to get it out, but whatever it is it doesn't budge. Any advice would be great!

Richgreenster

Don't do it... There is probably something else wrong with the system... Check out Clarks Garage to walk you through each test..

Litesonic

that is the adjustment part... but as above, there maybe something else in play. (your cover is missing, so something has been done in the past.)

kahlveen

I'm familiar with Clark's Garage. And thanks for the advice, but I'd like to try this to correct a rich condition at idle. If I don't like the effect of the change I'll simply put it back to where it was. This shouldn't be a problem since I'll be counting the number of turns it takes to fully tighten the screw from it's current position and I already know the resulting 02 sensor voltage reading at the current setting. Is there a more specific reason you'd advise not using this adjustment? Oh and if you could tell me how to get to that darn adjustment screw that'd be great!

kahlveen

Okay, so what I'm looking at is the adjustment screw? Do you really need "special tool 9230" that's specified in the workshop manual to turn this thing? I don't see how anything can fit to grip it. The sides of the screw are tight against the inner diameter of the tube. Is there a specific bit that fits into the hole in the middle of the adjustment screw?

Bri Bro

A 3mm six point should fit it. Looks like you also need some PB Blaster to get it to turn. That is one reason to plug it.

kahlveen

Thanks Brian. I think you're right. I've got T10 (2.74mm) and T15 (3.27mm) Torx bits. Do they make six point bits in metric?

Bri Bro

Sure, I would buy a metric set but if you want only one...

http://www.sears.com/shc/s/p_10153_1...=1297948724958

JohnKoaWood

I bought a set of T handle alen drivers, came with both metric down to 2mm and standard.. greatest tool set I have bought except for my ratcheting wrenches!

kahlveen

Thanks everyone for your help. I don't have access to another Bosch AFM for comparison and the workshop manual just confused me on this one. The pictures don't actually show what the adjustment screw looks like and instead of telling you what type of bit is needed, they tell you "special tool 9230" and show a picture of something that looks nothing like an hex wrench!

The good news is that I did get it adjusted, and I believe it's an improvement. After filling the hole the screw is seated in with PB blaster and letting it soak for a day, I was able to use a 1/8th inch (3.18mm) hex bit to turn it. The 3mm was a bit too small (may be because the screw fitting is a bit stripped). The screw was seated as far down as it could go which explains why without the oxygen sensor connected to the DME, the mixture was on the rich side. With the screw fully seated, the O2 sensor read ~850-900 millivolts. Once the sensor was plugged back into the DME, the mixture was corrected, but it resulted in an bit of an erratic idle. The problem with this situation as far as I can tell is that the O2 sensor is not operating in its optimal/sensitive-to-AFR-change range. In the end, I backed the screw out until I got a reading on the unplugged O2 sensor that fluctuated between 400-500 millivolts. I'm gonna take some more readings to make sure I've got it where I want, but the idle is much more stable now, and I think this is an important adjustment to get right if you want your oxygen sensor to provide accurate data to the DME and work effectively.

Bri Bro

Nice write-up

If you included the procedure (and picture) of how to tap into the O2 sensor connector, along with the picture of the AFM adjustment screw and the NB O2 graph, this would make a nice addition on Clarks garage. Tiltle something like "How to adjust the AFM without special tools and equipment"



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