Date:         Sun, 6 May 2001 23:33:36 -0700
Reply-To:     David Marshall <vanagon@volkswagen.org>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Marshall <vanagon@volkswagen.org>
Subject:      Re: I-4 conversion timing problem
Comments: To: Larry Alofs <lalofs@enteract.com>
In-Reply-To:  <3AF5DC1F.8A50AB72@enteract.com>
Content-Type: text/plain; charset="US-ASCII"

For Volkswagen, the first knock sensor was in the 1985 GTI CIS-E system.

Small - 'nit pickey' correction on your explanation of a knock sensor.  The
VW ones work on a timing map, so let's say (don't know the exact numbers
this second) 2000 RPM is +15 degs and 3000 RPM is +20 degrees.  It is UP TO
these numbers - it will not go past these numbers.  This is why you can
advance the timing at idle with no load on these ignition system to +12
BTDC - if there is knock the ECU will automatically retard the timing until
there is none, you will always be at the maximum advance that can be had
without knock.

David Marshall

Fast Forward Automotive Inc.
4356 Quesnel Hixon Road
Quesnel BC Canada  V2J 6Z3
mailto:info@fastforward.ca <mailto:info@fastforward.ca>
http://www.fastforward.ca <http://www.fastforward.ca>
Phone: (250) 992 7775           FAX: (250) 992 1160

. Vanagon Accessories and Engine Conversions
. Transporter, Unimog and Iltis Sales
. European Lighting for most Audi and Volkswagen models



-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of Larry Alofs
Sent: May 6, 2001 4:20 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: I-4 conversion timing problem


Stan Wilder wrote:

> Please explain "Just make sure your knock sensor is working!  ".
> I've never heard of this before.
> I've got an 83 Aircooled 1970 cc FI, so it might not even apply to me.
>
> Stan Wilder
> 83 Westfalia Air Cooled

You're right.  It's a more recent invention, never used in factory vanagon
engines that I know of.  Earliest I've seen is in an 88 Jetta, but I don't
know the whole history.
  In engines where the ignition timing is controlled by the ECU, it can
advance the timing until it senses the pinging from ignition too
early/octane too low. It then retards the spark just far enough to stop
the knock.  The idea is to prevent damage from pre ignition and still let
the engine take advantage of the extra power possible if you use high
octane gas.  Sounds good, maybe it even works.

Larry A.