Hi, im new to this forum, and new to porsches. Around three months ago i brought a silver 2001 996 turbo x50. I absolutly love the car but little did i know when i got it it was in safety boost ( 0.4 bar ). I was told to swap maf semsor, made no difference, so i took it to a specialist. He said their was a leak on the manifold and so it was fixed. When i drove the car it rarely produced 0.7 bar and when acceleratong hard it would boost usualy 0.7 or 0.6 and then after around 4500rpm boost start tailing off to 0.4 or 0.5 to redline. I was told this was normal??? I have now put on an agency power filter which is great and had an ruf race map on the car set to run 1.3 bar. Now the car will pull 1.0 bar and tail off as before but to 0.8 or 0.9. So same problem of not making enough boost and boost tailing off but just more of. My brother is a mecjanic but isnt to familiar with porsches, he thinks a sensor may be sending wrong signals to the ecu??? Any suggestion or idras would be very much appreciated. Thankyou in advance

 

i have no idea what your poblem is but if i was in your position i would find a good porsche tuner and have them run a diagnostic, i know england is a tiny little island but they must have a few good p'car tuners

good luck to a fellow brit

 

DV Valves are leaking?

 

Hook it up to Porsche diagnostic machine at dealer or you can get your own Durametric program. Check for codes. If none, built a boost leak tester like the one Colorinc built (do search here for boost leak tester). Test for leaks at pressure you should be at. Fix any leaks. Most of the time these two steps will resolve low boost problem. If not try replacing spark plugs. If that does not work ask someone smarter than me.

 

bleeding off of boost is generally due to leaks, hoses DV"S(Blow off valves) gaskets or possibly faulty waste gates

boost doesn't trail off unless your turbos are running completely maxed n dieing off which at .8bar stock they are not

pressure test the system from the turbos to see if it holds

 

Hi, thankyou for replies. One thing i forgot to mention is that one specialist pulled off ( what i believe to be ) the pipe going to the actuators just to test the car. After this the car drove extremely well and held full boost to the rev limiter. If the problem was from a boost leak or faulty dvs would the boost have increased any when mapped? Again thankyou in advance for very useful advice

 

Sorry, also the car has been on porsche diagnostics twice and came up fault code free!!!

 

the F hose is what that hose is called and it sounds like you either have a leak


would the boost increase when you flashed the car to try n build more boost maybe but it wouldn't hold.

 

Ive got the car booked in for oil and filter service and pit better plugs to cope with increased boost. I think the pipe the guy pulled off was underneath near the turbo

 

ok, if the car is x50 you should have 0.9-1.0bar not 0.6-.07 and you need dvs asap

 

As for tuners in England, I'm pretty sure that Manthey in Surrey if I remember correctly is a well respected tuner. I've never been to England, so I have no clue as to proximity to you. But you're getting a lot of good advice, it really does sound like a boost leak somewhere.

 

Ok guys, thanks for all the advice, ill get new dump valves fitted as soon as i can then repost on progress if any.

 

I would do the boost leak test first, it is easy and cheap to do. However, your problem does point to the DVs though. Perhaps the "F" Hose but those plastic DVs typically only have a 5 year life. The diaphrams could be ripped.

If you are a little mechanical and a hobbyist, doing the boost test is quite a fun project. I personally built a couple of test parts very cheaply. If you search on Boost or Pressure Test you should find it.

Pulling the actuator hoses off could be dangerous. Although they will start to chatter at about 1 bar. I would replace them with 1 bar units personally and adjust them to 13psi.

Good Luck.

 

+1 on the boost leak test, as well the DV may just be leaking, What fuel are you running to hope to hit 1.3 bar?? that's a little scary if you ask me.

 

Hi, im probably not the most knowledgable mechanic in the world but if i do attempt a repair i try to do everything to the highest possible srandard, i do realy enjoy working on the car so will try out this boost presure test. I feel i will need to swap dump valves anyway so will do that asap. I use the super unleaded fuel from the shell petrol stations in uk, 99 octane