Rev Limiters (was RE: Knock Sensor Q)

[lacelle@frontiernet.net (Erik La Celle)]

1. FPR = Fuel Pump Relay
2. This is the theory being bandied about, generally accepted but not
universally.  Having read the thread in a somewhat half-assed manner, I
remember there seems to be a difference of some sort between MK1 and
MK2.    There was some discussion of FPRs between the two with the newer
have more sophisticated circuitry, something about pulsing, etc.  The
other theory is that the FPR shuts itself down when the RPM is too high.
3.  No redline?
4. Can't help you here -- wasn't paying close enough attention.
HTH
Erik L
----- Original Message -----
From: ATS - Patrick Bureau <pbureau@attbi.com>
To: Jonas K. <jkarlsso@metabolex.com>; scirocco list
<scirocco-l@scirocco.org>
Sent: Saturday, May 25, 2002 11:47 AM
Subject: RE: Rev Limiters (was RE: Knock Sensor Q)


> okay I am confused again. (surprised..?)
>
> 1.)sorry for my lameness, what does FPR's? stand for ?
> 2.)So the knock box cuts the ground when the coil tell it the rpm is
too
> high ?
> 3.)And if the low compression cars (such as my JH 8.5:1) the terminal
31 is
> grounded, are you stating that my 85 has no rev limitator (not will to
test
> it right now I need the engine still, not really willing to try to
redline
> my car)
> 4.)And if that is true then all I need to do when I install the knock
box is
> to ignore terminal 10? or just ground it ?
>
> Hoping to figure this out by the time I install the engine in the car!
> ==========================================
> ATS - Patrick Bureau
> 1985 8v **Planning 3A/JH  Upgrade**
> 1988 16v ** FOR SALE : 1500.00$ **
> Web Site : http://longcoeur.com/scirocco
>
>
> =>-----Original Message-----
> =>From: scirocco-l-admin@scirocco.org
> =>[mailto:scirocco-l-admin@scirocco.org]On Behalf Of Jonas K.
> =>Sent: Friday, May 24, 2002 12:41 PM
> =>To: scirocco list
> =>Subject: Re: Rev Limiters (was RE: Knock Sensor Q)
> =>
> =>
> =>Hi all,
> =>
> =>I perused the wiring diagrams in the A2 bentley last night, in
> =>search of an
> =>answer to this question.
> =>
> =>Here's what I found:
> =>
> =>All the A2 cars have the following pin designation on their FPR's:
> =>
> =>30: Always 12v
> =>15: switched 12v
> =>87: output to power fuel pump
> =>1: goes to coil/ignition control unit
> =>31: either ground or to knock box.
> =>
> =>On the low compression cars, terminal 31 goes directly to ground,
> =>and in the
> =>High compression cars, terminal 31 goes to terminal 10 on the knock
box.
> =>
> =>So the knock box does _not_ trigger the FPR's activation, that's
> =>still done
> =>by the coil, the box merely provides the ground, which it can
> =>interrupt "at
> =>will".
> =>
> =>I forget who said the knock box gave a pulsed ground, but from these
> =>diagrams it seems that the knock box provides a full-time ground
until the
> =>rev limit is reached.
> =>
> =>This is why Honnold's solution worked. He tee-ed the wire from
terminal 10
> =>on the knock box into the ground wire for the FPR. Thus, even when
the rev
> =>limit was reached, the FPR is grounded. Elegant.
> =>
> =>When I installed the knock box for my 2.0 (aba/JH) install, I
> =>left the wire
> =>from terminal 10 unconnected. It'll work fine.
> =>
> =>A neat experiment in the real world would be for someone with a
> =>16v (keeping
> =>it scirocco specific), who knows what it's like to bounce off the
rev
> =>limiter, to tap in a ground for the wire from pin 10 on the knock
box.
> =>
> =>Then do back to back test with this tap _not_ connected to ground
(rev
> =>limiter enabled) vs. with the tap grounded (rev limiter disabled).
> =>
> =>Let us know what happens when the knock box is pushed beyond the
> =>preset rev
> =>limit, and how high it will rev. Also let us know at what point the
motor
> =>blows up. :-)
> =>
> =>If no-one steps up to the plate, I'll just have to wait a couple of
weeks,
> =>then try it on my brother's POS discarded beater 86 GTI.
> =>
> =>Jonas
> =>
> =>
> =>
> =>
> =>
> =>_______________________________________________
> =>Scirocco-l mailing list
> =>Scirocco-l@scirocco.org
> =>http://neubayern.net/mailman/listinfo/scirocco-l
> =>
>
>
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