I think I found why I can't tune my car for sh*t (including LTFT). My fuel pressure regulator is doing the exact opposite of what it should be doing. Vacuum causes the fuel pressure to increase and it doesn't respond much at all to boost. Here's two 15 second quicktime videos of what's happening. Fuel Pressure gauge is on top, boost gauge is on bottom. The boost gauge reads zero at 9 0'clock and 1 bar at 12 o'clock. Anything from 6 to 9 is vacuum. The FPR was set at 3Bar with the car off and the fuel pump running. It's about 3.2 bar when boost is at zero on the highway.
http://christopher.implex.net/StupidCar/FuelPress1.mov
http://christopher.implex.net/StupidCar/FuelPress2.mov
The boost gauge is tapped into the FPR line. I'm using the Buschur SX regulator. The fuel pressure sensor is on the fuel filter. What in the hell would cause this? I'd take the FPR apart but I wouldn't know what I'm looking for. Has anyone rebuilt one of these regulators? I've used silicone on both the hose bar for the boost source and the adjustment nut on top to eliminate boost leaks. I may try swap a stock regulator on just to make sure that's the problem, but I don't know what else it could be.
Any ideas? I'm surprised I haven't blown my motor over this problem.
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