Hi All,

I have been chasing down small leaks in hopes of fixing my intermittent high idle issue and occasional P0507 code. I am wondering how big a vacuum leak has to be to affect the idle. The car will hold pressure for a while, but it will slowly bleed away. The latest is a leak from the pressure sensor on the top of the plenum. The car runs and pulls well at 1.0Bar, but, as reading above, it may be compensating a little. I will perform higher pressure tests from the turbo inlet, but my thinking is that if my idle issue was caused from a vacuum leak, wouldn't it be pretty obvious under pressure? Up stream of the throttle body must see just about atmospheric pressure at idle, no?

I will get to the last of the small leaks, but I'm wondering if I'm barking up the wrong tree with a vacuum issue - at least for the high (1000rpm) idle. I can't help but think that the TB just isn't closing that last little bit. I have pulled it and cleaned it really well, but no joy.

If I can pressurize to about a little less than 10psi just after the air box and it will only fall a little bit over a couple minutes, can I move on and assume it isn't a vacuum leak? How sensitive is it at idle?

Thanks,

Franny
'04 X50 Cab

 

Markski,
I checked my car last week for boost leaks and found one major and one small leak.
Thanks for pushing this test! I bet most 996 turbos leak at some point.

 

Most do. I'm working on one the oem Ipd plenum section needed To be replaced. The bilt inn check valve was busted and pushing air into the oil cooler when on boost. You simply don't know untill you pressure test.

 

I am going to do a leek check this weekend!!!!

 

There is a small line going in to the inlet pipe just before the turbo on the drivers side. I am not holding pressure and getting air coming through that line. Should that be capped off when doing the leak test? Or is this a problem?
Thanks for the help.

 

No stop
It's your check valve on top of motor. It's broken. And usually the cuprit toast members cars.
It should not be blowing downwards.
Markski

 

Thanks Markski, is this the N75 valve I've heard about?

 

Nope.
Remind me tomorrow up send u the part number

 

Get this part. It will fix it

99611013570

 

Part ordered, thanks Markski!
Found the diagram of where the part is located, how accessible is it?

 

For you it probably will be a pita. Lower the motor on mounts. And good luck.

 

Yikes. That sounds like it really is a pita.

Let me know when you have a moment to let me use your leak tester! Thanks!

 

Marek,
You need to bring one of your beasts down to texas in October.
Robert

 

Last minute prepping for 1/4 mile.

 

You are correct, PITA, but it is done, now on to the next one. There is a small gray piece with three lines going into it just to the right of the y pipe. I'm getting a leak starting at about 13 psi cominG from the back side of this part, can't tell if it is a line or the fitting is cracked, see pic.
Is this something that should be replaced?
Thanks!