Drivers side nock sensor.

[spannerrash]

Hi all

I've just gotten around to sorting something out that's been bugging me for a while. Bank 1 (UK drivers side) nock sensor plug fell apart a couple of years ago and I've been holding it together with tie wraps. This has not caused me any problems or fault codes but just looks a bit crap.

However, even though I've had the inlet manifold off a couple of times over the years, I never noticed the cable route for the nock sensor until now. What the hell? Is there some special voodoo way of getting the plug or the sensor past what looks like a coolant pipe?

It looks to me like I will have to cut the cable in order to remove the old one. Is that correct? Also does the orientation of the sensor matter. Can I spin the new unit around so that the cable points toward the front of the car. Will the cable fit under the manifold?

Any guidance much appreciated.

Also does anyone know the torque setting? I guess that's pretty important to make it function correctly.

Thanks Frank

[steamship]

Let's start with the easy one. Torque setting for the knock sensors is 20Nm. I found in the following PDF, page 165:

Service Manual 8-cylinder engine (3.7 ltr & 4.2 ltr 5-valve AQF, AQG, ARU, AUW, AVN, AVP, AKC, .pdf

As for the cable route, here's a couple of photos from the following thread, from when I had a massive coolant loss, and then did as much work on the engine as I could:

https://forum.a8parts.co.uk/showthre...t=16865&page=6

This is the route of the original cable:



This is the route of the new cable. From memory, what I did was feed the cable from the 3-pin end underneath the coolant pipe, and then along the top to the front of the engine:



This photo shows the cable hanging down over the front after the manifold was put back on, and the next one is a zoomed in version, with the knock sensor marked in red. If you follow it up, you'll see the small gap that the cable sits in:

[spannerrash]

Thanks Sean, very useful. Also just read through your engine work post. Very impressive. Thanks for sharing.

[steamship]

Forgot to say, if doing the passenger side one, you do need to cut the old cable as it feeds down between the block and the metal timing belt cover, and you can barely get your little finger into the gap, but you can run the new one over the top... unless you just happen to be doing the timing belts at the same time, and you can run it properly.

[spannerrash]

Thanks bud.

[Adrian E]

I feel your pain on this - my supercharged S5 has both knock sensors in the centre of the V. Naturally one only started playing up shortly after I’d had the supercharger off for a load of work to be done (2nd new thermostat being the reason, but also did updated PCV and injector service etc while in there)

Given it’s 6 hours labour to get the ‘charger off, I’m waiting for the other one to kick the bucket and throw the EML before attending to it!