Rev Limiters (was RE: Knock Sensor Q)

[cory.langford@icbc.com (Cory Langford)]

 Just a wild thought here. 

If the Knock Box tells the Relay when to shut down the fuel pump, I
would suspect that would be done via a voltage/no voltage situation to a
specific pin from the box to the relay.

So if that wire was cut (the connection between the relay and the knock
box) would not the rev. limiter be removed?  If there was a need for
voltage, I am sure you could connect the correct voltage from another
source to keep the fuel pump working.

I do realize this brings up other issues, like safety if the engine cuts
out and the fuel pump keeps on going, but who needs safety for a engine
that can rev till it fly's apart :)




-----Original Message-----
From: Jonas K. [mailto:jkarlsso@metabolex.com]
Sent: Thursday, May 23, 2002 9:57 AM
To: ATS - Patrick Bureau; scirocco list; Chris DeLong
Subject: Re: Knock Sensor Q


On 5/23/02 6:43 AM, "ATS - Patrick Bureau" <pbureau@attbi.com> wrote:

> you know I read your replies 3 times... and you make no sense what so ever.

Aagh, sorry, guess that's what I get for trying to be thorough. :-)

> 1. you are saying that the 8v and 16v knock box are the same (or you don't
> know)

Yes. :-) Don't know for _sure_, but they should have the same wiring.
Best
bet would be to use a harness and box from the same (8v or 16v) that way
you're safe.

> 2. then you say the relay has nothing to do with it, but the cut off is
> controlled by the knock box

What I meant is that the relays between the RD 8v's and the PL 16v's are
the
same. The knock box controls at what RPM the relay shuts off the fuel
pump.

> now if the knock boxes are the same and the relays are not the controlling
> device, how does the
> knock box know its controlling an 8v (6800Rpm) or 16v engine (7200 rpm) and
> adjust itself to the proper engine?

Aha, I see the confusion. The 8v and 16v knock boxes have entirely
different
part numbers, and somewhat different interals. They are clearly not the
same. The main diffenerce AFAIK is that the rev limits are set
differently
between the two. I thought this was understood, and that the question
was if
a 16v knock box would connect up to an 8v harness and be a plug-n-play
bump
up in the rev limit.

> what I want to know is
> what controls the rev limitation (knock box? relay?) if knock box, then
> logic dictates that an 8v and 16v knock box would be different JUST because
> they rev limitator are set different  (no matter if they are wired the same)

The rev limit is strictly set by the knock box. The 8v is different in
this
respect from the 16v.

> and btw.. I am talking about SCIROCCO here not A2.

Right, I got that. What I was telling you is that when you put the
knocksensing system into your scirocco, you will retain your stock fuel
pump
relay. This one does not take an input from the knock box, so regardless
of
which box you use, you will not encounter a rev limiter.

I've got the 8v system in my 85 and in my 78, no rev limit other than my
right foot, and frailed nerves.

Hope that cleared things up, sorry for the confusion.

Jonas