A tip on knock sensors for all you guys with stock ECUs...

[BillyT]

...and built motors, or anyone that has ever unbolted thier knock sensor for any reason.

Torque spec on a knock sensor is extremely critical.  Too tight, and they will be too sensitive.  Too loose and they won't pick up anough.  Not 100% sure, but I think they are supposed to be torqued to 18 ft/lbs...  double check that number before you use it, but I am pretty sure that is it.


All you guys with built motors and crazy knock voltages...  this may be your problem(too tight of a knock sensor).  Double check the sensor and get back to us.

[Dizzy]

I could be way off base, and i don't have my Bentley handy since Im' out of town, but I thought it was a typical VW spec, ie xx lb ft plus 1/x turn.

[Don®]

During my build I did not remove the knock sensors they remained as they were. Funny thing is I'm not getting crazy knock sensor voltage anymore. full boost at 25 psi to 7000 rpm I see as high as 22 volts on #2 and the rest at about 16-18 volts.

If and when I see higher voltages is when I'm off-boost between 3500-4500 rpm.

Other than that I cannot complain.

[enginerd]

If that's the case dizzy, be sure you use new bolts, as they will never retorque exactly the same way. Those kind of fasteners are actually loaded up to the yield point, and won't net the same strength the next time around.

I almost never use new bolts, because according to vw they are all like that, but this one, flywheel bolts, and head bolt's always replace.

[Dizzy]

Same here, dogbone and subframe I don't replace.  But things like you listed you'd always want to.

[BillyT]

I reused headbolts on the AWD motor I had that made 460 wheel...  never had a problem.

Not advising it, just saying I did it.

[southofheaven]

as per Vesis on my laptop....

knock sensors should be torqued to20 Nm, no additional turns

[Dizzy]

Which is 14.75 lb/ft.   Thanks Pat.

[slickfisher]

Yes,

Now that I've sold all my VW tech info ( some things don't change). And I had to use Bentley's e-bahn   . 20 NM is the spec. We had a little trouble initially in 85 when they first started using knock sensors- re-tourqing/replacing, but I don't here much about them anymore. Nothing new the pressure on the crystals in the knock sensor will effect the voltages. Of course too much could damage them. I seem to remember 13 ft lbs on the old knock sensors.

[southofheaven]

its like the ROYAL with cheese vs the quarter punder thing.....

I dunno what the fuck a ft/lb is he he