2001 Boxster S engine turns over but as tough time firing.

[Turd]

My 2001 Boxster (affectionately named Turd, recognizing its macadamia metallic colour and recent performance) has recently become an inconsistent starter. The engine turns over great and sometimes it will start just fine. Other times, hot or cold, it will take a number of engine revolutions before it starts to fire and then finally starts, then runs fine. No dura metric codes or engine light. It hasn't let me down yet but it's embarrassing and will wear out the starter and battery in time. Relevant work in last 6 months:
New fuel pump, new fuel relay, new spark plugs, new air filter, new fuel filter, new axles, new headlight switch, new transmission oil and engine oil.

Threads lead me to believe next step is the crank case sensor replacement. Any ideas?

[freezing14]

hi there , i know a lot about no start or hard start

just spent a week on my 996 to figure it out ( see the mystery tread )

when it does not start , do you have fuel and spark or both missing

i have had the same issue with my audi allroad , would run fine one day , then no start what so ever , but then i would wait an hour and it would run fine , totally random no start condition

test your crank angle sensor , you should have the same voltage ( about 2.5 volts ) for 300 degrees of the revolution then spike to 3

i have the test in the shop manual but they say to use an oscillioscope but a cheap analog or good digital multimeter will show you, the old analog is good as you see the needle fixed and then jump , the cheap digital sometimes dont respond fast enough

[Turd]

Thanks everyone so far. I'm getting closer to solving Turd's unwillingness to start. I installed a new CPS, crank position sensor. It helped but did not solve the problem. Turns out I am losing fuel line pressure when Turd is turned off. Must be a check valve not holding or something. I'll update when it's solved.