Surging and erratic boost

rguzz at rguzz at
Sun Dec 31 11:56:06 EST 2006

186k miles 200tq TAP chipset (yeah I know) there is a worsening surge intermittently beginning at around 2.5-3k rpm. The external boost gauge as I run the car a bit hard will hover at 16 psi, sometimes very steady other times wildly oscillating as I appreciate a missfire while driving.
This all seems a bit intermittent, though lately more present than not. I don't have the means to pull codes. Plug wires, plugs, BPV should be good.
Is this how a bad WGFV behaves? I had a bad flywheel sensor that did something like this but the car cut out violently and briefly when this was the problem.
I don't think it is the TAP software. Coil was swapped out without a change in behavior some months back. But things are worsening.
I'd like to clean, check function of all sensors (hall, etc) but I sort of think these function on an all or nothing basis.
Could this be as simple as a boost leak? I don't hear one and power seems good. Should I replace the WGFV on a trial and error basis? Where else should I look?
Thanks for your input.

More information about the 200q20v mailing list