When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
A few days ago I noticed a new sound when on the throttle.... a sonorous groan; an asthmatic wheezing note coming from the passenger side rear. I just figured it was a diverter valve sounding off and ignored it... until today when I made a WOT pass down a country road... the car would only boost to .4 bar. After playing around awhile on/off throttle, I was able to hear a woosh with the groan... a boost leak.
Now high on my list is a loose charge pipe, as I had changed out the plugs and coil packs just last month; necessitating removal of the intercoolers and piping. I checked the connections by pushing and pulling on the ones that were easily accessed under the bonnet; they looked fine. I think I'd need to pull the bumper cover to check the rest.
However, if a hose had come loose, then wouldn't it be a massive leak ? ... I can't understand how the car would run at all. The car in fact idles and runs at light throttle too well to suspect a vacuum leak of any magnitude (?). What about a bad diverter valve? Are there other areas that commonly cause problems?
Come on Rennlisters! Save me from the embarrassment of taking my car to the dealer with the story "I fixed my car. Now it won't run"...
Check the hose clamp on the F tube where it comes off of the Y pipe on the left side. Lets just say that i know that i can make woooshing sound if not tightened
I too recently had an issue with the boost only at .4-.5 and last week I had leak test done. My mechanic used a Snap On Smoke machine for the leak test. We removed the air cleaner/filter box and plugged up the intake tubes and proceeded with injecting smoke smoke into the throttle and intake system. Waited for a minute for the smoke machine to do its thing and inspecting the areas of the diverter valves, throttle area, check valves, venturi tubes, etc. we could not find any smoke coming out of them. Waited another minute and still nothing was noticed up top of the engine area. We then raised the car on the lift and continued with the testing, and then found smoke slowly billowing from the intake manifold pressure tube. We continued testing and looked at the same pressure tube on the rear area/passenger side and no smoke. After conclusion of the initial test and no sight of smoke coming out of the throttle body area, we decided to cable wrap the rubber vacuum lines just to make sure, and then continued with injecting smoke into the system and still no sign of smoke. I was prepared to have the venturi tube, check valves, gaskets and other items replace, but only the pressure tube/pipe PN# 99611062570 is to be replaced. The only issue with this test upon trying to order the part was that no dealer or OEM parts supplier has it in stock and will have to come directly from Germany. I did order the part and will have to wait 3 weeks before I can replace the mine on the car. My mechanic said that once we get it replaced, he'll do another leak test to make sure all is well. I've attached a picture of the part here.
To test the condition of DV's.. One has to get a vacuum pump and test the control port nipple. It either holds or it doesn't. If it doesn't you need to replace the DV's..
The second place that I'd quickly check is your "F" tube that connects to each DV.. This tube can split on high boost situations..
I'd also check the pressure boost hoses that connect to the "Y" pipe
As Paul mentioned build a boost test cap and pressure test.
Kevin: I'm so bummed as I was anticipating the arrival of your tune.
I've rented a hoist and an able chevy mechanic for an hour this afternoon. We are going to check my previous work to make sure I haven't left a charge pipe un-clipped... sure hope he speaks german. If it's not a real obvious problem, then I'll likely take to to AR auto service in Lake Oswego. They are pretty knowledgeable about 996tt's... I think that Gabe used to work at a Porsche specific tuning company. Hope to have it sorted before your tune arrives in the mail.
The car does not need to be put on a lift to check the above "items" that I mentioned.
From your datalogs, you had boost, and the boost met the requested boost. So a hose has popped off the "Y" pipe/intercooler OR you have a failing DV or a cracked "F" tube. These are the simple in your garage things to check...
ALL 996TT owners need to build a pressure test rig. I recommend the factory method of testing thru the side intake plenum.. You can also test at the intercooler/lower hoses.. Regardless, test and learn the drill.. It's like changing oil>>it will get easier everytime you do it.
...Regardless, test and learn the drill.. It's like changing oil>>it will get easier everytime you do it.
Very true! First time I did a boost pressure test I fumbled around for a while, but eventually found my boost leaks. I'm sure I could do it again in about 1/4 of the time!
... Smoke machine for the leak test....only the pressure tube/pipe PN# 99611062570 is to be replaced.
Maybe Kevin can chime in but something doesn't sound right...
The part you are showing looks like the inlet pipe to the drivers side turbo. That's not a pressurized part of the system being pre turbo and seems very unlikely to cause a boost leak. #16 check valve, however, is a frequent failure and if bad, will dump boost pressure into the nipple on the side of the part you have shown.
I suspect you might have a failed #16 check valve (996 110 135 70) rather than the part you are trying to source from Germany.
I'd bet this has something to do with it. Looking thru the engine bulkhead, it looks like the upper right inter-cooler connection has come loose and even spit the o-ring out. ...looks like I'll be taking the bumper cover off again this weekend.
Since your car is a early production (less than 2003) I would order up 4 new boost pressure hoses (strong recommendation for those that own 2001 and 2002 production cars). They have been updated and will successfully handle 1.4/1.5 bars.. The nice thing is they are inexpensive. At a minimum order the upper hoses and new clips..
Since your car is a early production (less than 2003) I would order up 4 new boost pressure hoses (strong recommendation for those that own 2001 and 2002 production cars). They have been updated and will successfully handle 1.4/1.5 bars.. The nice thing is they are inexpensive. At a minimum order the upper hoses and new clips..
Porsche warehouse only shows one one out of four available. The rest are in Germany. It looks like I'll end up plugging the old line back in and then throwing your tune at it. If it pops, then I'll have to order from Porsche of Germany... unless there are other aftermarket lines out there that are readily available? It's not too much work to r/r the bumper cover. The major pain is avoiding breaking more of the brittle mounting tabs off of my new $1k set of OEM tail lights. ... but that's another story.
Edit: I see that Pelicanparts has a set of Forge hoses for the car.
05-15-2018, 12:16 PM
Boost leak
