The pop off might be leaking just because you're putting pressure behind it when normally it's under vacuum. I wouldn't worry about it unless it still fails to start with everything else okay.

=1 what David said. Well, have you tried to start it yet?

Here you go, thanks for everyone's help. I know it will take more tuning.
https://youtu.be/h-998cQ1qdc

^^^Nice

Check if it's leaking under the toilet seat cover or around the base.
If the latter, it's time to reseal.

It looked like just around the seat, there's a big o-ring that the lid closes on. Don't know if they sell those seperatly that could be replaced.

Success!

I have a 25-year old pop off valve on mine. Haven't had any leak problems. If the O-ring looks good, and is pliable when you stick your fingernail into it, it's probably fine. AS someone else mentioned, when the engine is running, the valve is under vacuum which keeps it pressed shut. If you have doubts, squirt a little gasoline or starting fluid around the valve and see if it changes how the engine runs. Just make sure your squirt does not go into the metering unit, or that will change how the engine runs.

Okay thanks for the tip. As the weather gets warmer I would like to check the timing, oxygen sensor and maybe do a valve adjustment. Don't know when it was last done. I have only had the car 2 years now. I've done it on my old 912 but not a 911.

So, it was a intake runner not seated?? Crazy that the smoke went UNDer the shroud, and none leaked up. I guess your shroud is a tight fit against your intake manifold boss.

That's why it was so difficult to detect because nothing was coming up from the top even though the bolts were almost finger tight. I thought at first it was coming from the passenger side but removing the heater duct gave me a visual check inside. Car started right up afterwards. I was so careful to tighten all the hoses and missed the easier area's. I guess you always need to double check everything.

Too bad you didn't do the valve adjustment while you had the CIS off.

No worries about that, Joe's now a CIS installation expert.

Told you it wasn't our little pal the green wire. ;)

Good Job.......
 

Welcome to the CIS club. Next goal is to learn to drop the motor for better and efficient troubleshooting.

Tony

Thanks for all the helpful responses and updates here. I'm currently going through a no start issue and reading all this gives me some hope and also some reason to take the smoke test seriously. Will be doing a DIY smoke test in the next couple of days.

Anyways, good stuff here, thank you!