L-jet running rich Options

[Ctrout]

I know that everyone here has D-jet but does anyone know of any L-jet gurus anywhere? My car has smelled like it runs rich since I got it. While doing some exhaust work this morning, it was confirmed by the black soot everywhere. I thought I read somewhere that these cars ran rich from the showroom floor. I have backed the idle adjust all the way out with no apparent change in the richness of the mixture. It did change the RPM to a point though. I read in one thread something about coming in from working on the car and smelling like I had been standing next to a diesel campfire. That's me!

[Brando]

If you've ever adjusted the mixture/richness on a 944 you'd see that they are in fact the same design Air Flow Meter. (Not the exact same unit).

Removing the cover and moving the wiper while it is running you can see exactly how it adjusts the fuel mixture. It will increase or decrease the idle speed a small amount, you will hear knocking or pinging or hear it smooth out.

Do not be afraid of opening the cover. Do take caution, because if you unspring the wiper from the mechanism (you'll see the two-points holding a large sprocket in place) you will have essentialy ruined the unit. The IDEAL way to adjust this is to adjust the wiper with the spring retainers in place, see where it runs best, then remove the spring retainer that holds the sprocket, and move it to the next gears over either direction.

You stated that adjusting the idle mixture screw does nothing. The screw you are turing is an air bypass. Unscrew it, it let's more air pass at idle. To properly adjust the mixture you must adjust the wiper/resistor.

If you have qualms about doing this yourself, take the car to a local Porsche mechanic and ask them to help adjust your mixture. It may cost a few pennies but they should be able to do it within a few moments. If their adjustments have no effect they can at least give you a run-down on what else may be causing it to run too rich. They may or may not have the equipment to test your emissions and let you know if it is running too rich or lean.

Just to ease some fears, the adjustment with the wiper and circuit board I mentioned is the same adjustment made on all 944s to adjust for smog purposes.

Addendum:

Do make sure you have no vacuum leaks. Usually the little elbow point between the AFM, plenum and Auxilary Air Valve go bad (intake leak), the oil cap is on and sealed well (another big intake leak possibility) and that your vacuum advance and retard lines are good (other possibles). If you have an intake leak you will never be able to get the mixture correct (as scott said).