I think you are still more thorough than a lot of others working on their cars. I’m sure cleric will chime in, but if no replies by the end of the week I’ll ohm out my extra sensors.

 

in regard to the pinout diagram, I found several on the web. is the 2003 G35 Coupe the same pinout as the 2003 Z33 350z?

 

found the FSM on NICOclub, and checked continuity from pin #15, viewed from the back of the plug, wires entering to ECU. got continuity, and my new knock sensor ohmed out exactly the same as my old one, .559 (20M setting) so that tells me it should be working fine. Now I'm clueless

I pulled up an old thread for knock sensor and have been working over there too. https://g35driver.com/forums/g35-cou...ml#post7216351

 

so today I installed a complete new intake manifold gasket set, checked and rechecked the sub harness and main harness for continuity and shorts, checked the knock sensor for continuity to ground on pin2, and continuity to pin #15 at the ECU on knock pin1. All checked out. The new knock sensor ohmed out at .559, exactly the same as the old.

Assembled the MD 5/16 spacer carefully using factory gasket on the bottom manifold, and applied Return To Service 1min rtv and clamped onto the top half. Now it is at least manageable to service this thing without spending an hour scraping old rtv.

Reset the ECU with the ignition and pedals. Verified no stored codes on the OBD2 scanner. Starts up smooth, I'm feeling good about it. Warm her up and take it out to relearn the maps in the ECU. Going down the highway, I can tell its just missing something again. Pulled over, and checked codes... P0327..knock sensor low input. WTH??!

What now? I'm at a total loss

 

If you replaced the harness for the knock sensor I have no idea. Dang.

 

You mentioned having to reconnect grounds; are you sure you got them all? Checking two of the grounds is one of the troubleshooting steps for that code. As odd as it may sound the two grounds are in the interior (behind the dash).

 

I thought it was showing a pic of the front of the engine for that FSM troubleshoot step, it shows 2 grounds, and I only have one there. I even went into the harness and looked to see if one was broken off..I'll check under the dash tomorrow.

 

Update. 3rd top end teardown today to get to the knock sensor. Started at square one and tested "everything". Discovered in the end, after pulling the harness 3/4 of the way out of the engine bay that I had a broken wire that was giving intermittent signals, unfortunately it was in the "new used" knock sub harness I installed. I built a new shielded knock harness from scratch and tested it at every step as I was putting it back together.

on the bright side, I'm now pretty quick at throwing this thing back together. at 3:30 when my son got home I was under the car installing the harness on the transmission, the whole intake mani was off, battery out..etc. Fired it up after restting the ECU at 4:50.. (this is important bc I had to leave at 5pm to take my son to his 1st JV soccer game) I made it

With all the loose grounds, plugged evaps, swelled charcoal canister, multiple OBD2 codes..and other issues I've had since August when it hit the road again.... I forgot how quick this thing really was. Feels like a beast again. Just got back from a spirited "ecu relearning" test drive and no codes and she pulled HARD.

After 3 teardowns.. and pulling my hair out... I can finally sleep again.

 

Further down there's another set of pictures showing one ground near the ignition key cylinder, and the other near the blower motor. Glad you got it figured out.

 

The second ground is for the TCM on a 5AT equipped vehicle, you only have one ground on yours.

 

Update.. still pulling P0455 large evap leak. New gas cap is on the way. Really hoping this isn't still manifold/spacer related..