1999-2009 [Subscribe to Daily Digest] |
T7 monitors air mass flow rate and 1 or 2 points of pressure, depending on model year. The boost gauge measures air mass flow rates, not pressure. With the hose popped off, the turbo compressor had no back pressure and flow rates were high. The engine would not run right. It may have fallen back into T5 engine management mode, but was still confused. T5 did not have an air mass meter, but calculated combustion air by air pressure and RPM etc. That in turn was refined dynamically via the O2 sensor.
I think that if the mass air flow meter fails, the T5 fallback would be drivable. But with the MAF operational and hose popped off, the system was not programmed with a workaround.
I do not think that the turbo was damaged in any way. You were getting some unfiltered air for a few minutes.
Pressurized turbo hoses need to have oil free contact surfaces. The force if the clamp creates friction that prevents blow off. Sometimes people will lube thinking that this allows for easier installation or preventing the hose from been removed in the futures. Same concerns for cooling system hoses. When radiator hose barbs were brass, hoses used to bond and were often only removed destructively. I learned my lesson the hard way after applying silicone release agent [grease].
Turbo hose interiors can be oil contaminated. If a hose and removed and refitted, there is a risk of contamination of the contact surfaces.
Rubber compresses and the preload pressure of the clamps is reduced. Not so much of a problem with [conformal] spring clamps, but a real problem with and non spring loaded band clamps.
When a hose pops off at max boost it is quite a disturbing event. I had this happen on my NG900 with a highly and uniquely modified boost control system. Lessons learned there led to the development of the MBC+A. I was not able to implement that myself as my NG900 had then been totaled by a high speed moron.
posted by 64.216.10...
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