Altitude sensor....no mixture

[P944stud]

My 87 944 has rough idle, could it be the altitude sensor, part number 944 606 051 00. Also, I took my car in to get the mixture set and my mechanic can only get it to 0.1------should be between 0.8-1.0. Could this sensor be not working properly and causing this problem? Anyone with prior work done changed this out. I HAVE REPLACED EVERYTHING ELSE, SO NO GUESSES !!!! My theory on this is that, if the altitude sensor is not working properly, the computer could think that it is say 10,oooft ( which means less air) and it is leaning out the fuel, thus way low mixture. Any thoughts?

[Scott R]

I would not think that would be the problem. What exactly did your mechanic adjust? I only ask because the variance your talking about is too great for a failed sensor. This sounds more like is time to open the AFM and adjust the spring back a few clicks. What year and type 944 do you have?

[P944stud]

The AFM is new, just replaced it. What do you mean open it up and adjust the spring. I'm thinkin now that my mechanics engine mixture machine must be out of whack. Gonna go tomorrow to another place and hook it up to theirs- and see what's going on. Still think it's the altitude sensor-it's the only part I haven't replaced. 87 944 127k

[Scott R]

Inside in the AFM there is a spring actuated arm. It is adustable by position. I think I remember and I may be incorrect here, but counter clockwise is leaner. Clockwise is richer. My 951 came from a state without emissions testing, and it was way out of spec. I needed to move my AFM three clicks lean to get it to pass. This adjustment is directly proportional to the DME air/fuel mixture control. The screw that is covered by the plate on the AFM is a fine mix adjust screw. It can get you .5 .1 adjustment. But for major adjustment the cover must be removed and dialed in. I put my 951 on a three gas anylyzer that I have and adjusted from there. Some members on this list can do it just by smell! I am not that good.

[P944stud]

I figured it out, the first guy I took it to, and had the mixture adjusted, his machine was not working properly. I took it to my mechanic and he fixed it all up to specs. Thanks for the input