My 996 porsche turbo wont go over 1 bar boost /new turbos/new exhaust/larger intercoolers/ new electronic program

boost is produced by adding extra fuel in the combustion process to create a hotter exhaust and more exhaust gas pressure
boost is produced as the exhaust turbine winds up from that extra heat / pressure produced from the extra fuel
loose intercooler hoses , cracked intercooler will loose that extra boost
so it could be from the fuel controller ( throttle position sensor) is not working properly, boost pressure being lost by holes in the system or-- from experience-- a problem turbo unit ( bent vanes on the compressor wheel from impurities hitting then at speed creating an excessive turbulence and slowing down the turbo action
best take it to an accredited service center and have the fault codes read and a diagnosis of the problem

turbos generate boost fro the heat in the exhaust and the free flow of exhaust gases. That means the amount of fuel through the injectors and blocked cat converter or exhaust system. OK now you know how the boost is generated look for areas that will loose the pressure (boost ) between the turbo and the manifold Look for loose boost hose clamps on the turbo and intercooler and intercooler and manifold. Look for cracks or holes in intercooler. Look for blocked air cleaner as turbos use more air through the air cleaner than normal. Finally look at the compressor blade of the turbo as any bent fin will slow down the turbo wheel giving less boost. Have the turbo tested for correct operation

tubo units get compressor drive power from the exhaust pressure acting on the turbine wheel, not after the turbine wheel so exhaust pipe /flange leaks are non effective
what you problem indicates is a holes in the intake system after the compressor wheel from bad intercooler pipes /hoses loose and or holes in the intercooler
another place of failure is a faulty boost dump valve that is not allowing pressure to build up at all
make sure that the air filter is new as any restriction is a problem
of course you could always take the car to an accredited turbo repair shop and just talk about it and get information as to the possible problems

I assume its the 6.0L diesel...If so sigh......double sigh.. I had one of these...triple sigh. I need a bit more clarification. How many km on the engine/vehicle. Also, you say that it blows black smoke while running at a constant speed at 2600 rpm, or while you are accelerating to 2600 rpm. Also, when you say the boost goes down, does it decrease by itself, or when the throttle is let off. The boost naturally goes down when the throttle is released (not trying to be a ****, i dont know how much you know). However, if the boost is going down by itself, while the engine is under load (its not supposed to, it should stay constant) it could be a couple of things, which "can" contribute to black smoke. If there is a leak anywhere from the turbo to the intake of the engine, it will cause the engine to get less boost, which means less air into the cylinders, which means black smoke. Check all of the connectors/tubing coming from the turbo to the intercooler, and from the intercooler to the intake manifold and see if there are any problems. The more costly problems which results in boost going down, and black smoke, deals with a problem with the wastegate on the turbo (controls how much boost is produced, and when too much is being made, it will bleed off excess pressure). So if your wastegate is malfunctioning, your boost will go down and you will get black smoke cause the engine is not getting enough air. also, around 160km...80mi, the injectors "can" start to go on the 6.0L diesels....I would check the turbo for leaks, the tubing for leaks, and the intercooler for leaks (a big rock can punch a hole in radiators and intercoolers...intercooler will be in front of the radiator). I hope this helps

bigger is not better when it comes to turbo units as Leyland found out when they fitted a turbo to a 690 diesel that resulted in the destruction of the engines and damage to the company reputation of a reliable engine manufacturer
Subsequent engineering found that a much smaller turbo produced more power without the destroying the engine
The turbo fitted to the engine originally is the correct unit for the maximum power that the engine mechanicals can handle
What you have to do is to ensure that the variable vanes of the turbo are working correctly and there are no boost pressures lost from intercooler leaks and loose hoses
Run the fault codes to determine sensor and actuators for the existing turbo are fully operational

what is your actual psi? check into the other divertor valve or the n75 valve(electronic)

You just can't turn up the turbo boost any more with the new engines. If the turbo start to boost more then the PCM is programed to, it will cut the fuel pressure down and you loose more HP. Here is a link for you if your looking to get good HP out of your 6.0 liter diesel. You can replace the wast gate for the turbo with a higher PSI rating but your going to have to by a electronic boost builder for the PCM so it will not kill the fuel pressure soon as you start making more boost. http://www.thoroughbreddiesel.com/bd-diesel/turbo-boost-builder.htm and http://innovativediesel.com/ Good luck and hope you get the HP your looking for to get out of your engine.

this a turbo problem, you must to repair turbo

Yes,through extensive modification. These include but not limited to, a different intake manifold,exhaust manifold,exhaust system,different computer, intercooler, & much more. Don't do it unless you really want to learn. This is a major operation.

Hi, the only real way forward is to get the fault codes read from the on-board diagnostic system. In the meantime, you could check for clogged /loose / fallen off vacuum pipes and splits in the intercooler pipework.

Hope this helps. If this "fixes ya", I'd appreciate a rating for my reply, If not, please delay the rating and add a comment with any extra info you have and I will try to think of something else.

Cheers, D.