RE: Knock sensor problem ? non-Scirocco

[Jonas Karlsson <jkarlsso@metabolex.com>]

Randy B wrote:
>
>Sorry about the non-Scirocco post but thought
>it might be relevant to Scirocco's as well

Definitely! Many on this list (incl. me) are running knock sensors on 
their cars.

>When I advanced the timing on the 1.8L 8V RD
>motor in my 87 Jetta GLI to more than the factory
>6deg. I got terrible pinging. :( This is a factory stock
>un-modified car)

That is definitely not normal. The principle is that when the knock 
sensor detects knock, the KS box retards the timing until the knock 
disappears. As such the timing is constantly being adjusted to "optimal" 
advance. 

If it still knocks when manually advanced, then something is not working 
right. Check that the KS is connected and that it looks fine (ie, wires 
are fine, the sensor is not cracked, etc.) If it checks out visually, 
try removing it and torqueing it to the right spec. The Box could be 
malfunctioning, but usually when it goes, the whole car won't run. Check 
the vacuum connection to the box, obviously fix any leaks you might 
find. 

If you don't notice anything wrong, then try checking that there is the 
appropiate continuity for all the plugs from the KS to the KS box. I 
have a diagram if you want it that helps you trouble shoot it. 

As a last resort, try replacing the box. I don't know of any way to check 
the box other than the little test light port. I've never done that 
though, so I couldn't help other than regurgitating the Bentley. 

HTH
Jonas
85 Scirocco 2.0 w/ Knock sensor



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