Noob Chipping/Turbo Failure Prevention Question (LONG)

[Dr. Jekyll]

I didn't have a problem when I had my MTM chip. Just throw a MBC in parallel and set it to 16 psi or so. That would be the safest chipped setup, aside from TAP which somehow manages to run vacume all the time :-p

[BlackMagicTT_S4]

What is wrong with running in vacuum? (Excuse the noob question!) So all I would have to do to prevent boost spikes would throw in an MBC in parallel? That doesn't seem too complicated...would 16psi be the best level to set it at, or lower?

[VandyS4]

Vacuum = no boost. Vacuum all the time means no boost all the time. While that would be splendid for the turbos, you probably want more power out of your german sports sedan.

[Indyxtype]

[Dr. Jekyll]

MTM is a great chip, I loved it, its just a little on the slow side. It has lots of low end torque but tapers boost quite a bit in the upper rpms. This is good for the turbos though since they have to work their hardest up there. I think MTM boosts at 15-16 psi and then tapers as it gets close to redline. So to save your turbos I would set the MBC at exactly that, so you have no boost spike at all. An MBC in parallel is very easy to do (as long as u don't break any Y fittings on the vac-hoses in the process >:-o ). Just search for some pictures and diagrams, there are a couple really helpful ones that people have posted in the past.

[BlackMagicTT_S4]

[VerrÜckt]

time with MTM.

Personally, I would get a GIAC X chip. If you're concerned with boost, you can always turn down the boost via Lemmiwinks.

[SchagenWagen]

His logs does not remotely correspond to mine or others with MTM. The fact that second set bleu in short period of time just supports that theory.
I am not a doctor, nor I ever saw the patient, but if I had to guess: he might had someting wrong with wastegate actuator.
Now, what supprised me the most that after years of reading this forum YOU and MIG did not realised that simple fact (or atleast give benefit of the doubt)

[SchagenWagen]

[Indyxtype]

The way a turbo works, is that exhaust gasses pass through the turbine side and as they flow cause an impellar to spin. This impellar is directly connected to another blade on the compressor side. This compressor side is what does the work throwing more air to the motor. The more air to the motor, the more exhaust gas out and thus the impellar spins even more. This process continues expenentially unless some of this exhaust gas is diverted from the turbo. This is the role of the wastegate. The N75 valve basically controls the wastegate by means of providing a reference pressure. If this reference pressure is lower than the actuall boost pressure, the wastegate will stay closed and the turbo will build more boost. However, when this reference is above, the wastegate opens and the turbo gets less exhaust gas.
The ecu receives information regarding the boost pressure going into the motor and compaires that to the requested pressure determined by various factors such as RPM, enginge load, throtle position, etc. Depending on how these two values compare the ECU adjusts the N75 duty cycle to adjust the reference pressure. As such the ECU can regulate when the turbo stops building boost and when it begins to let off boost thereby preventing the turbo from spinning off into ablivion.
While this system works very and allows active control over the turbo and boost pressure it maintains the inherint problem in that it is slow. Because for this system to work, the ecu must first perform its calculations. Next, it must wait for the N75 to take action. Finally, it must still wait for the wastegate to open before the turbo begins to spin down. As such when a turbo spins up rapidly, it often can create a surge or spike.
What a MBC (manual boost controller) does is allows an instant response. By venting any pressure above a specific limit, even before it goes to the N75. Thus, the pressure spikes are bled off even before they are generated.
There are lots of posts that talk about running a MBC to cut of spikes (most using X-chip) and even more about using it to souley to regulate boost when using K04's. Some people also recomend an electronic boost controller as you can build in a factory like taper and many other features, however these cost about 10 times as much and are overkill to use alongside an N75. Do a search in the archives and see what you can come up with, but as soon as I chip my ride this summer I will be throwing in a MBC. If you do decide to bit the bullet, here are a couple of links to places to get them.

http://www.vastperformance.com/products.html
http://www.boostcontroller.com/index.php?maincat=12