How much boost swing is too much?

XJCoupe

Veteran Member
Joined
Dec 25, 2005
Location
D.C. Metro
TDI
none
I ran the boost diagnostic procedure listed on the Ross-Tech site to get a baseline before doing mods. There's more variation between specified and actual boost on my car than there is on the Ross-Tech example graph.

So, how much deviation is too much? I've had no DTCs, and the car drives well. (I've had it for about two months.) I did notice that planting the pedal on the highway (@70 mph) briefly produced a pretty good cloud of smoke... I'm guessing that's happening because the fuel is being delivered, but the boost is lagging.

Today I tested the resistance across the terminals of the N75 valve (15 Ohms), and cleaned it with carb cleaner. The next time I have the car up, I'll check the operation of the VNT linkage. Before I "chip" it, I'm going to install boost and EGT gauges to keep and eye on things, but in the meantime would like to make sure things are operating as they should.

Thanks.

 
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