CIS question (10:1 compression and knock sensor?)

[tberk@mindspring.com (T Berk)]

Ben Bell wrote:
> 
> Hi guys, my first time ever e-mailing the group, yay!  Some of  you may
> know me from the vortex as RoccoRacer.  Anyway, I'm having trouble
> getting my car within California legal emissions levels, and I was
> wondering if any of you could tell me why.  I have a '91 Jetta longblock
> 
> in my car, and I'm pretty sure it's a 10:1 compression engine.  I
> vaugely remember reading in the 8v forum on the vortex that a knock
> sensor (which I do have on my car) won't work properly on cars with 10:1
> 
> compression, can someone verify this for me?  I had an idle problem, and
> 

That is exactly backwards; 10:1 compression is when you WANT a knock
sensor.


> a new O2 sensor seems to have stopped it's wandering.  Now it'll idle
> fine for a little while, then get a bad signal and run way rich.  I'm
> basically stock right now other than the '91 jetta engine and the bottom
> 
> of a 16v airbox.  Any info would be greatly appreciated.
> 
> Thanks a lot!
> Ben
> aka RoccoRacer
> '86 Scirocco 8v
> 


The ECU problem your tech mentions might be caused by poor grounding, as
in poor or marginal signals. New O2 sounds good but there is more to
this.  If I understand you correctly you have a 91 Jetta long block
(block + head) and it's installed in a 1986 Scirocco. Where did the K/S
come from? Who did the work?

TBerk