Rev Limiters (was RE: Knock Sensor Q)

[pbureau@attbi.com (ATS - Patrick Bureau)]

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
=>
=>
=>
=>
=>
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