Because TPS refers to throttle positioning. So it would make sense to most people that if you're foot is on the floor you're in high boost mode. That's not the case on an internally gated turbo trying to make 20+psi out of it. We have this wonderful little thing called part throttle. Meaning that you can be at only half throttle and get 20+psi but the safc won't know that you're making that much boost because it only sees that you're at half throttle not full throttle.
When referencing map, the safc determins wether or not you're in high boost or low boost by how much boost you have lol. It still works off throttle control to an extent but it will make it's changes based on boost not throttle. Like I said, with an extremely stiff wastegate spring you could be at 1/3 throttle and getting spikes of 15+psi easily. Hell I got 24psi spikes on stock turbo at half throttle. So the throttle doesn't really control the boost all that well.
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O4 PT Cruiser non GT
Stock b****es, come get me 
Sporting new Nikon D40 w/18-55 & 55-200...it's a learning curve that's for sure!
SoCal's fastest PT Cruiser 
Last edited by Turbocruiser13 : 11-21-2007 at 02:35 AM.
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