more on 16v knock sensor diagnosis

[xaeryan@hotmail.com (Ryan Hockenbury)]

Toby, you are describing the exact same problem my car has... NO power at 
all (starts are very difficult, esp. uphill) until 3000 rpm, when it "kicks" 
from the timing advancing to the right degree.  I replaced my knock sensor 
control unit, as well as the sensor, and it went away... for a few weeks.  
Then it came back, so I replaced the knock sensor.  Same thing - went away 
for a bit of time, then came back.  My knock sensor box tests ok, and even 
after I take out the sensors to put in a new one, they register the correct 
resistance.  In other words, something electrical is plagueing my car.
PLEASE, if you figure out what the problem is, let me know.  I don't have 
any money to go and replace any parts I think could be causing it.  But just 
as an idea for you, I was thinking of replacing the coil and the coolant 
temp. sensor.


>From: "T. Reed" <treed2@u.washington.edu>
>To: scirocco-l@scirocco.org
>Subject: more on 16v knock sensor diagnosis
>Date: Thu, 15 Aug 2002 01:58:55 -0700 (PDT)
>
>[snip]
> > Plug the connector back into the knock box and turn on the
> > ignition.
> >
> > Connect the back of pin 12 to ground (find pin 12 before
> > you plug the connector back into the knock box).  If your
> > fuel pump relay turns on the fuel pumps, your knock box is
> > shot.
>
>John,
>
>Thanks for the tip on taking apart the connector - I never noticed that it
>came apart!
>
>Are you **SURE** it's pin 12? Pin 12 goes from the knock box to the
>ignition control module. Looking at the electrical diagram it seems
>much more likely that it's pin 10 (the wire that goes from the knock box
>connector to the fuel pump relay) that you would want to ground to test
>this. On my car, grounding pin 10 ran the fuel pumps.
>
> > I jumpered my fuel pump relay to ground and drove the car
> > that way for almost a year (sometimes its hard to find a
> > cheap knock box).  It works, but the ignition is retarded
> > (as I mentioned in the other thread) and the fuel pumps
> > will be on anytime the ignition is on (no automatic
> > shutoff after 2-3 seconds).
>
>Today, I did the following
>- checked cam to crank timing: dead on
>- checked for resistance in ecu grounds: less than 0.3 ohms
>- checked voltage at coil 15(+) while cranking: 10.5 to 11.5 volts
>- checked coil resistance: secondary within spec, primary is 1.0 ohms
>   (spec is 0.6 to 0.8 ohms) - could this be causing such poor power off
>   the line? I'm doubtful that it is, but I suppose its possible. Has
>   anyone fixed something like this by replacing the coil??
>- connected an LED test light to terminal 4 of the knock box and performed
>   bentley test. The light came on when I turned the ignition on, went out
>   when I started the car, and did not come on when I revved the engine
>   above 3000 rpm - which the bentley says indicates that no faults have
>   been recorded. So, it would appear to the untrained eye that my knock
>   box is 100% functional except for the FPR output. But I have no idea.
>
>I don't have an adjustable timing light to measure the advance at
>different speeds. There aren't any other tests listed in the bentley for
>the knock sensor system so I don't know how to continue...
>
>Is there some way I can just disable the entire knock sensor system
>without having it always retard the timing? Unplugging the knock
>sensor didn't seem to change anything, but I can't say for sure.
>
>The sensor is of type II (the kind with the wire coming out of the center
>and the resistance spec of infinity) and was torqued to 15 ft-lbs.
>
>The car is pretty much fine above 2k rpm (knock on wood, get it?) but runs
>terrible below that.
>
>Thanks everyone!
>
>-Toby
>
>
>
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