[torsen] Re: manual boost controllers, and ECU functions
QSHIPQ at aol.com
QSHIPQ at aol.com
Wed Feb 7 10:19:05 EST 2001
I'm not a self proclaimed anything on these lists (except "idiot"). That
said, let's take my position, and make it perfectly clear, there is *NO*
conflict in my opinion or assessment of ABC (aftermarket boost controllers)
since day 1. Many quattros thru my shop since, hasn't changed things at
ABC's are good additions to cars that don't have any WGFV function, Gary,
which includes the audi 10vt motors pre 86, and my 87 4Runner turbo. Both of
which use spring tension against manifold boost only as a boost control
The *problem* with audi WGFV is their function in terms of leakage and
ability to control what they were designed to control. Neither WGFV, the top
feed (slow/inaccurate) nor the bottom feed (leaking/inaccurate) accomplish
boost control as well as a stepper motor. That said, the problem with ABC's
is (for now at least, the gap is getting closer) that they don't have as many
inputs to boost control as the factory units, IOW, the ABC's have a primary
function only (boost), they don't care about secondary inputs to
accomplishing primary directives.
So, in an audi, when the CAT goes up, the WOT isn't activated, the engine
temp is too high, the knock sensor is howling foul, the altitude is too high,
etc, there is modified or no boost profile to the WG. In all the inputs
above, the ABC doesn't care, you programmed in 20psi, you get 20psi, with
So, my position has been crystal clear in terms of ABC's vs WGFV, and what is
really needed, is for a *real* techno nerd to figure out how to add an ABC
stepper motor to the WGFV tables in the audi ECU. It's a lot of work since
ABC's and WGFV operate on different functions, but it's not impossible.
Until that is done, the WGFV is better at accomplishing the *safety*
parameters of the primary function of added boost. ABC's add a higher degree
of risk to the primary function of boost, especially if the knob is located
near the nut behind the wheel.
I've driven and evaluated several customer cars (esp S cars) that have
installed the ABC, then disconnected it and installed a proper chip upgrade
to a car with WGFV. I found the ABC tends to ramp faster, give more
consistent boost levels, and give greater flexibility to control upper limit
boost. HOWEVER, the fact that is does, isn't necessarily a good thing, a
WGFV may be giving lower ramp up based on the secondary inputs to the device.
That said, I believe audis would have great gains in performance using a
stepper motor to accomplish primary boost function.
I own the profec B, cuz I was fascinated by a certain audi tuners religious
application of them. I put it on a vehicle that has the greatest potential
benefit from it, my 4 Runner with no WGFV function controlling the boost. It
took me forever to get the thing dialed right, and I'm still convinced that
it could be better than it is, but the technology of secondary boost
functions isn't quite as sophisticated... yet. No doubt in my mind it's
gonna go that way. BTW, I will also be installing an ABC on my 83 Urq, since
it has no WGFV function at all.
Controlling the WG is the key to optimum turbo performance. Using that POS
WGFV that audi uses is behind the technology, and it fails quite regularly on
any tweeked turbo car. I have yet to hear of a stepper motor failure on an
ABC. Kinda makes ya think...
In a message dated 2/1/01 12:44:38 PM Central Standard Time,
erickson at teleport.com writes:
> I guess my question is this: if the ABC's are the great solution you
> claim, why aren't you running them in any of your _Audis_?
> I'm just trying trying to process conflicting advice from the original
> self-proclaimed turbo nerd. And it's making my head hurt.
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