So I tried to change my knock sensor on my 99 Maxima, I went over the thread here on changing it, but mine is different. There is a vacuum thing of some sort in the way, and the manifold comes down lower in the way. There doesn't seem to be a away to get to the knock sensor really, I removed the bolts for the vacuum thing, and moved it a little out of the way, and got an assembly of extensions and a universal in, but the angle on the universal is almost a 90 degree angle, and does not allow it to turn. Has anybody tackled this without removing the manifold?

Here is a pic of the vacuum thing.

 

That's the swirl valve actuator. Just move it out of the way and the rest is the same. It's a tight spot, take the intake plenum out and it makes it easier to move around and see down into the valley where the ks is. I've changed it 2x on my 99. The correct extensions, swivels, socket etc make it a 15 min job.