Redlyne_mr2

I have a super charged 2002 996 c2. My car kicked out a high idle CEL, P0507. Research tells me its a vacuum leak. Car ran decent but now since my inspection it wont stay running, idles horribly (perhaps I completely dislodged a line).

Ive included some pics of where I think the leak might be, the issue is the access with these lines. Can I access the other side of the line from under the car? Are there any other lines that might be a culprit?

Line location is left side engine bay, running from intake manifold location at the back of the engine to intake manifold location at front of engine bay.

thanks

5CHN3LL

Do you have access to / can rent a smoke tester?

I don't recall ready access to many vacuum lines from under the car, but I never went under with that in mind, so I won't swear to it.

Have you tried unplugging the MAF sensor? A bad MAF will also cause a stumbling idle.

E-gas calibration? Worth a try, anyway.

Ahsai

Try a e-gas throttle recalibration first. Leave the key in the last position beofre crank for 60 seconds without touching the gas pedal. Turn the key to OFF and wait for 10s and it's done.

Since your lines are not stock, you may get limited help here. In general, smoke test the intake is the fastest way to id an intake leak.

The Radium King

vacuum leaks are more noticeable at idle (when your car is at full roar at 7000 rpm moving 3.6/2=1.8 litres of air per revolution, a popped vacuum line doesn't matter much, but when it is sipping air at idle the additional air can bugger things up).

the vacuum system is designed for ... vacuum - when the engine idles it creates a vacuum which is used for a few things - fuel pressure regulator (depending on the year of your car) smog stuff, resonance valve operation, brake boosters (depending on the year of your car) and sport exhaust valves. when you have a forced induction system you are pressurising this system. most of the vacuum lines are press-fit, so the pressure from the supercharger probably popped one off. hard to get at. easiest way is to probably back off on the two hose clamps that hold the intake plenum in place and pull it off - might give you enough access to root around with your fingers and find the culprit. there's also a one-way valve in the vacuum system that keeps the vacuum from bleeding back in to the intake - the forced induction might have broken it, or forced some oil into it and gummed it up.

but i have been wrong before ...

Macster

Generally the vacuum lines are pretty much confined to the intake area. I have not bothered to try this but I suspect you'd require pretty long arms to reach these from under the car.

The space in there is tight. Hoses are old and don't take kindly to being jostled. A recipe for trouble.

With more room one used to be able to run the lines and see if touching a line, moving it about -- gently -- affected the engine. Or in some cases where the lines weren't too numerous just replacing all the lines with new ones. I used to keep a couple of lengths of different sizes vacuum hose (and gas hose) in my garage for just such a thing.

The problem is the lines are probably not replaceable with off the shelf vacuum hose but are probably specially formed and plain old hose would get a kink and cause problems.

Given how tight things are in there you might have some success with spraying carb cleaner -- the kind that comes in an aerosol can -- at the various hoses and hose fittings. While you are at it treat the intake gasket seams too -- a supercharged engine blow an intake gasket out -- to a spray of carb cleaner. The idea is when (if) you hit the leak the engine reacts to the carb cleaner.

yaknart33

Try using a squirt bottle with water and spray it in the suspect area ,it it starts run rough when you spray there's your vacuum leak.That will help pinpoint the leak.If your scanner has real time data monitoring you can monitor the fuel trim data as well.