vishal

Anyone from the Bay Area willing to spend some time with me and help located a vacuum leak? This is really frustrating and I would appreciate any help anyone can provide. Lunch is on me if we can fix the problem. I'm in Berkeley.

Thanks.

boost feen

I live up in Sonoma about :45 minutes away but I dont think I even need to come to you. Heres what you do go to the auto parts store and buy a can of brake parts cleaner. With your engine running at idle nice and warmed up spray the brakleen on all possible vacume lines and spots that there could be an air leak like intake hoses manifold gaskets etc.. When the rpm's raise up when you spray just a certain area you have narrowed it down to that spot, if it is a real minor leak you might need a inductive engine analizer or something with a really fine incremented tachometer on it that you can have in the engine compartment I have a Sunpro one.

Danno

How do you even know it's a vacuum leak? What's the car doing?

vishal

The car has a slightly rough idle which appears every so often. Also, the car is only making 6psi and not until 4k rpm.

I don't know if this noise is normal (as one mechanic told me it was), but when I move the throttle ever so slightly, there is a hissing sound coming from the throttle body.

Any help would be appreciated.

adrial

Whatever leak you have, its not on one of the small hard vac lines.

I would check your intercooler pipes...make sure they're not cracked...make sure all hose clamps are tight.

If you get a 944 fuel filter and saw it in half, then hook up pressure, that is a perfect fit into the intake boot. 5-7psi is plenty...the boot will flex a good amount.

There is an O-ring between the intake manifold and the TB, couldn't hurt to replace that and clean the TB at the same time.

Someone will probably come to the rescue

Goodluck!

Turby

that also sounds like the intrecooler pipe to the throttle body to me. Is your idle screw in place? also check all the smaller hoses around the int cool pipes.

Danno

Yeah, sounds like one of the major large hoses in the intake tract. Start at the air-box snorkel and check each and every connetion for tightness. Actually, you should take off the airbox and start at the turbo outlet onwards. The large hose coming out of the turbo is prone to splitting. Reach underneath it and feel the short radius for a slit. If not, then follow the airflow and check every single hose clamp along the way. Might even be a good idea to undo the hoses and clean the clamping surfaces with acetone.

vishal

OK guys I found a hole on the bottom of the pipe that goes from the turbo to the the Intercooler. I have patched it temporarily which has cured the idle problem. However, I am still not making any more than 6 pounds of boost. Any other suggestions?

Danno

First make sure you don't have any other leaks in your intake tracts. Did the fluttering/hissing sound go away?

Try pinching off the line that goes from the cycling-valve and the wastegate. The CV is that little hockey-puck under #3&4 intake-manifold runners. This removes any control signals from reaching the wastegate.

Then slowly drive the car and so several partial-throttle runs. Notice the boost response and max-boost level. Gradually increase the throttle. A stock car can peg 20+psi with this test, so be careful!

If you can develop tons of boost, then you've got a defective cycling-valve that's not controlling the wastegate properly. However, if you still have low-boost with the control link closed off, then you have a bad wastegate; probably a weakened spring. Test that out by shimming the wastegate.

vishal

Danno, which line is that exactly? From the front, I can see one line coming from the LBE, and another going to the J boot. Where is the line that goes to the wastegate?

Danno

Follow the line leaving the LBE. It should end at the wastegate eventually. So clamp shut that line anywhere after the LBE and before the wastegate.