[s-cars] Re: Motronics MAP - some fuzzy logic included

Thu Jan 22 16:59:22 EST 2004

My 2 cents:

The next step up from the VMAP development would be to
allow for the ECU to control a stepper motor or
quicker solenoid, allowing for more precise control.

Come on, Feico, I know you can do it.  =)

As for me and my HKS electronic dial-a-boost, I just
keep it at 20psi on pump gas and 22 on the good stuff.
 Still have to get it on a dyno and reflash the ECU's
fuel and ignition maps, hopefully that will happen
within the next couple weeks.

Joe

--- Robert Pastore <rpastore at animalfeeds.com> wrote:
> Scott:
> 
> Generally agree with all you've said WRT boost
> controllers; several years
> ago I invested in the Apexi AVC-R, and wound up
> removing it after I learned
> how to write a boost map for the motronic.  
> 
> But I disagree that the fuzzy logic (FL) is what is
> putting your engine at
> risk. 
> 
> As I understand it, the FL is looking at the delta
> between the actual boost
> experienced (as per the MAP sensor), and the desired
> boost (per the
> programmed boost profile), and then adjusting the
> controller's output to the
> actuator to minimize that delta, whether it be
> changing the duty cycle of a
> FV, or a stepper motor.   If you want more on how it
> works, I think Julian
> Edgar from Autospeed did a great job of explaining
> it in the series of
> articles on the intercooler/water injection
> controller they built.
> 
> The integration and interaction of boost control
> with the ignition and fuel
> control of motronic provide a much more
> sophisticated management system than
> an aftermarket controller can provide. Just like you
> said, it is a function
> of the number of inputs, data points on the maps,
> and the tools the
> controller can control as outputs.   The boost
> controller can only vary
> stepper motor or FV duty cycle. The motronic can
> reduce ignition timing,
> dump extra fuel to cool the cylinder, and shut power
> to the WGFV to reduce
> boost, all as safety measures to protect the engine.
> 
> I see the primary shortcoming of the boost control
> system on the AAN to be
> bottom chamber only boost control (the WG is  slow
> to react and leaks boost
> into the exhaust via the WG valve-to-guide
> clearance),  as opposed to the
> earlier Audi (and most aftermarket boost controller)
> top chamber control
> systems.  I think the change was probably due to the
> regularity with which
> WG diaphragms tore under the earlier system, because
> the pressure delta
> across the diaphragm is greater, thus faster acting
> and more violent.  The
> change probably solved a warranty/durability issue,
> but was IMO an
> engineering compromise that resulted in less actual
> boost control, [
> strictly my theory] and the creation of "overboost"
> as a great marketing
> gimmick to describe the period of time it take the
> inferior actuator system
> to reel in a rapidly spooling turbocharger.  
> 
> The other problem is the speed of the stock WGFV.  
> It is slow and soft.
> It is interesting to see that ECS has taken this pig
> of a valve ( or
> derivative thereof), and marketed it as an upgrade
> to the b4 s4 crew.   It
> seems that the B4 s4 has a faster active WGFV, so by
> putting in a slower
> one, boost levels climb and you go faster.      
> 
> rgds,
> Bob
>  
> 
> -----Original Message-----
> From: QSHIPQ at aol.com [mailto:QSHIPQ at aol.com]
> Sent: Thursday, January 22, 2004 1:38 PM
> To: CaptMagu at aol.com; FvAMI at aol.com;
> pizzoman at yahoo.com
> Cc: s-car-list at audifans.com
> Subject: [s-cars] Re: Motronics MAP - some fuzzy
> logic included
> 
> 
> Let's explore this a bit Hap.  Computers can't
> really learn, these 
> controllers you speak of are referred to as fuzzy
> logic boost controllers.
> Fuzzy logic 
> as applied to a boost controller will only be as
> good as the S car Motronic 
> when it can accept as many variables in the boost
> profile.  Currently we
> have 
> MAP, engine temp, dual knock, throttle position,
> altitude and CAT.  IMU,
> none of 
> the boost controllers on the market can account for
> these variables.  They 
> can *assume* their is something wrong within the
> parameters of the fuzzy
> logic 
> program, but it can't *identify* it if it's not an
> input.  Then what
> happens?
> 
> Well it can't code anything or flash you a ck engine
> light to advise you
> that 
> the reason for fuzzy logic interrupt to a boost
> profile is for a specific 
> reason.  So, by definition fuzzy logic can't *learn*
> anything.  It can only 
> sense, via it's specific and only inputs, that it
> can't give you what you
> have told 
> it to.  So, one could argue that a fuzzy logic could
> be better than a non 
> fuzzy logic external boost controller (see below),
> but I'm not at all
> convinced 
> that this is even close to a Motronic boost
> controller.  
> 
> The best part of ANY external boost controller could
> be argued to be the 
> stepper motor function.  It's quick and it's
> accurate and it's failure rate
> is 
> almost nil.  That doesn't at all equate to the
> controller itself being
> better, 
> only the mechanics of the valve actuator of boost
> being better.  
> 
> Further, I'd ask the question in "fuzzy" logic, how
> does the controller
> learn 
> that you've fixed or changed some parameter to allow
> 'full' boost again.  
> Does it continue to apply your desires, then accept
> a lower value?  That
> could be 
> scarey.  When you climb into the mountains (by
> definition a boost reduction 
> in the motronic >10,000ft = no WGFV function),
> what's fuzzy logic think of 
> that?  I don't believe it thinks at all.  I
> personally believe fuzzy logic
> boost 
> controller are looking ONLY for turbo surge line as
> the indication of
> profile 
> adaptation.  Add in a limited number of inputs, it's
> primary adaptation is 
> surge line based.  Even then, by my thinking, it
> will fail at it more times
> than 
> it will succeed.  Why?  Cuz FL have to constantly
> learn.
> 
> I argue that if indeed this is true, then I'd rather
> have a manual boost 
> controller that let's me do the fuzzy logic (fair
> and reasonable knobben
> dialer 
> argument).  Cuz my argument is that a FL boost
> controller is constantly
> putting 
> your engine into the danger zone, by definition, it
> has to to apply FL to
> it's 
> adaptation.  Your hi and low settings are based on
> your estimation, not
> based 
> on the actual engine function or the parameters
> motronic is conservatively 
> monitoring.  
> 
> Point of reference 012204, I make the claim that FL
> boost controllers are 
> still second to Motronic in terms of input
> parameters and safety in
> attaining 
> boost levels.  My suggestion is to take some of this
> seemingly unlimited
> budget 
> dollars and getting yourself a good motronic
> programmer to really explore 
> options within the motronic box.  Bosch made a darn
> good integrated boost 
> controller, it needs a little tweeking to make it
> great.  IMO, it's within
> the 
> 
=== message truncated ===

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