True Confessions - Oopsies, it didn't work

[scotricker]

You may recall my announcement that I finally found it ! the reason I can't check my oil with the engine running and the cap off.

https://forums.pelicanparts.com/porsche-911-technical-forum/1107581-911sc-stall-idle-oil-filler-cap-off.html

Well it worked , when the engine was cold-ish, but it was snowing outside, so tested in the garage only, with the door open , of course.

So, yesterday , I had the opportunity to take the car out, get it up to temp, and try it again. No deal, died right away.

The idle has always been at 1100 , can't get it any lower, even with it all turned in. That makes me think it must be a pesky air leak somewhere.

So, here we go again, I'll be looking for the dreaded air/vacuum leaks all over again, but I'll wait until the weather warms up a little .

[GH85Carrera]

Yea, vacuum leaks are sometime really hard to find. A real smoke test is often the only way to find them. Often the intake is the source of the leak.

[john walker's workshop]

Try pinching the brake booster hose. They can crack where they go over the torsion tube.

[boyt911sc]

Scot,

You have undetected vacuum leak/s with your CIS. Why would your cold idle not go over 1300 RPM this time of the year? If the ambient temperature is below 50°F, your initial cold idle should be high (1300~1400 rpm). What is you cold control pressure?

Without using a smoke generator, you will be lucky to find or identify those hard to see leak sources in your CIS. You must create a positive air pressure inside the airbox with smoke to be able to find them. It takes only a couple of seconds to locate the culprit/s provided you have the right set up. Keep us posted.

Tony

[Quicksilver]

My first knee jerk is that the restrictor (930-107-289-00) in the big crankcase to oil tank breather hose is missing but that wouldn't explain the 1100 idle. Still worth checking for the restrictor.

[targa80]

I had the same issue after repairing a blown air box revs at 1100 with idle adjustment fully clockwise. There is no real shortcut when it comes to finding vacuum leaks. Built a cheap smoke tester and found several injectors leaking. Bought new injector sleeves and new O-rings,re-staked the sleeves. Retested and then re-adjusted the CIS system with gauges.