Mike:
Thanks for taking the time and putting so much thought into the logic. I am attaching a photo of the paper towel I used to wipe the tailpipe this morning. I also wire brushed the tailpipe area so I could start out clean. I did a quick continuity check from the engine to battery and it has continuity, but I did not shake out any sensor circuits due to lack of documentation. The engine bay of the 968 is a nightmare compared to the 911. I got sidetracked drilling and tapping some 8mm holes which carried the gravel pan. PO had them wired on with baling wire.
I started it a few times today, and we took it for a ride for half an hour or so. I just wiped the tailpipe again, same blackness. It is definitely running rich, and gets loaded up pretty quickly. It also seems to be lacking power and responsiveness. Starting was a non-issue; it started in about two seconds every time I tried it today, both hot and cold.
Without documentation, I have no clue how it feeds back to the computer, but I do agree it is in open loop at start up. I might pull the plugs out tomorrow to have a look; my guess is black. Porsche probably has a spec for checking the check valve via pressure loss per uniy of time, again, no clue.
How similar is the 944 engine to the 968? Is it a 944 with a variocam and really big pistons. Are the electronics common schematically?
Maybe it just has the flu
I may have to schedule a doctor visit, or send the GF to the dealer and sweet talk some photocopies of the workshop manual relevant sections.
Pat
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Got sidetracked power washing and tapping new holes.
