Can someone direct me to an description on how to replace the knock sensor on a 2004 Infiniti I35? Understand it's the same as a 2003 Nissan Maxima. Thanks!

 

I have not personally done this on a vq35, only a vq30, so I can not verify the information here. However, it says you don't have to remove the manifold though, just the air ducting.

https://maxima.org/forums/5th-genera...-location.html
https://maxima.org/forums/5th-genera...ck-sensor.html

 

I've replaced them on the vq35. I took the intake manifold off to access the valley between the cylinders to get to the knock sensor (like the first picture above). I remember seeing info on the site about accessing the knock sensors without removing half the engine, but it was a major PIA! Its not terribly difficult, just time consuming. While you are at this level of removal, you might as well replace the spark plugs.

Hope this helps.

 

I just did this on my '02 GLE. Took only 30 minutes, and I have big hands! There is no need to remove anything but the black plastic air filter housing and hose leading to the throttle plate. Once removed, you have clear access with a socket and extensions to the knock sensor chamber in the middle of the engine. The socket and extensions will work for bolt removal, but be prepared to have to hand thread the bolt when reinstalling. I have permanent scratches on my hands, but got it done. Most people's hands will actually fit into the chamber to reach and turn the bolt. Please be sure to get the correct knock sensor harness, or be prepared to modify the sensor and a 4th gen harness!

 

Excellent comment, very informative. Thank you. This is everything I needed to know.

 

pulling the upper and lower intake manifold isn't that hard of a job but there's always the risk of connectors breaking.

​​​​​​the first time I took the upper off I did some modifying so I can take it off faster next time

 

I did this a few months on a 3.5 without removing the manifold. It can be done. When putting in the new sensor, I put the bolt on the sensor and a tiny piece of painters tape to help me guide it "home" by feel. Then pulled the tape while finger on the bolt.

 

I’d be very interested what modifying you did on your UIM…

 

when I had the original DE I mainly just got the NWP VIAS delete to eliminate all the stuff on top and tucked away the electric vacuum valve, and moved the green evap service port to the top of the transmission. my car also never had the bracket on the back of the intake manifold that bolts it to the head either. I also have all studs on the lower and upper intake manifolds. makes changing out the spark plugs way faster. also ditched the engine cover along with under hood insulation, it just traps heat..

 

I see you also have modified your valve body. Or did you install a big bore? I used a block off plate for awhile, eventually went back to stock. I was losing too much low end acceleration.

 

valve body? big bore?

 

I'd argue the following isn't recommended.

I replaced the knock sensor twice on a 1999 Cali spec i-30 vq30de that i picked up as a beater for cheap. To do it properly you have to remove the intake manifolds and access the v of the engine (real big pain on cali spec, emissions equipment in the way) anyway, the the cheap knock sensor I put on crapped out after a couple weeks and i didn't have time to redo it properly.

Instead of pulling everything again, I bolted the knock sensor on a metal bracket from the rear cylinder bank to the throttle body. Make sure there's metal contact from the block to the sensor. It worked for around 2 years before a cousin wrecked the car.

I'm used to putting at least mid-grade in my VQs, but it's probably a good idea to use premium gas If you modify the knock sensor location to prevent knocking