Well this is just my luck. After my ordeal several years ago when I first got this car on the road that turned out to be caused by a fake "OEM" knock sensor I purchaed off of eBay (seen here: http://forums.maxima.org/3rd-generat...me-issues.html and here: http://forums.maxima.org/dealership-...ff-artist.html), I've been running with the 470k resistor and had the KS bypassed. I had a wheel bearing get so bad it was unsafe so I parked the car about a year ago. So, while the car has been down over the past year I installed a brand new OEM knock sensor and harness straight from Nissan (among tons of other stuff).

Long story short I finally fired the car up today. I've touched nothing mechanically on the engine since I was last driving it about a year ago except the knock sensor and harness. When I parked it it ran perfect and had no CEL.

So I finally start it up today and it runs rough and has a CEL and three fault codes. Codes 13, 21, and 34. 13 is coolant temp sensor, kind of odd since its new, but whatever. 21 is "ignition signal circuit". Not sure what to make of it and the FSM isn't much help but I'll swap in my power transister unit from my other VE and see how it reacts. And what is code 34 you ask? Knock sensor. You've gotta be kidding me! This POS hasn't ever thrown a single CEL or ECU code even when I had a bona fide completely fake KS in there! Now I have brand new OEM stuff and it's giving me the freaking code. Unreal.

Anybody have similar issues with new KS and harness? I guess I'll throw a resistor in there tomorrow and see if the code will stay away. I'll be pissed if so. Doing that annoying KS job for nothing. And I really dislike driving in Texas summers with the KS bypassed.

 

Have you replaced the gas in the tank? A year is an awful long time for gasoline to sit and in theory would result in the rough running. Dunno about the coolant temp sensor issue, but in theory it could be knocking pretty bad with nasty gas, which MIGHT set off a knock sensor code.

 

Man that sucks. Hopefully it is a bad gas issue or something else that doesn't require redoing the job. Funny how it spit out all those codes at once, hard to believe brand new CTS and KS are both faulty. Hard to believe a brand new anything would be faulty.

 

It had less than about 1/8 tank of gas in it. Before I started it up I put in 7 gallons of 93 octane. I figure the fresh gas would hopefully drown out any old crap in there.

I also should have added in my first post that the engine hasn't sat this entire year, just the car. I have started the car and let it warm up and idle in the driveway periodically. The last time was about 4 months ago, and each time it has run perfectly. But it has not been started since the new KS until now.

The thing is if it's knocking the knock sensor should/would just retard timing and not send a fault code to the ECU. The knock sensor code doesn't get thrown due to knock it gets thrown due to a faulty knock sensor or harness. So engine knock is irrelevant to and separate from the CEL and ECU code. Theoretically even if you have knock, the knock sensor would just retard timing and not give a CEL or error code. Right?

I'm gonna go get a new CTS and stick it in there and start it again and see if that code goes away. Then I'll swap my transister unit from my black VE in and see if I can fix that "ignition signal circuit" circuit then try the resistor for the KS.

 

Okay well before heading out to Vatozone for the CTS I decided to swap over the power transistor unit from my black VE before leaving.

Stuck it on and the car starts up and idles smooth with no CEL.

So wtf, power transistor unit somehow affects the knock sensor and CTS?

 

PT affects the accuracy of the spark timing, I guess. Flaky PT = erratic spark on a VG, not sure if the COP system on a VE is equally affected.

 

The transistor unit does what a transistor does. Switch or amplify a source. I don't think it has anything to do with timing, just takes the ecu signal and relays it to the coil(s).

Jame: ECU diagnostics don't serve much purpose as everyone knows. I wouldn't even worry about why it's throwing a bunch of random codes. ECU just knows it's running like crap. You should try using the supposed bad transistor pack in the donor car and see what happens.

 

er, yea that. but intermittent/inconsistent spark quality due to a bad PTU could cause false knock readings, right? The z31 guys like to 'upgrade' from the Z31 PTU to a maxima VG PTU (requires re-pin of connector) because it's supposed to be better idle and better response. Maybe it's just newer and theirs are worn out.

 

I guess so. They wouldn't be false readings though I don't think if the timing is messed up. In that case, I can see where you were coming from saying it "controls the timing". In a way it does, considering it could turn into a train wreck if the unit fails.

 

Well I took the car on an initial little test drive today and halfway down the street the stupid CEL pops up. I wanted to see if the car would drive fine despite the CEL/codes but couldn't really test it since the brake pedal was super soft for some reason. Came back, bled the brakes again, and the pedal is still super soft. I guess I need a new brake booster.

Anyway, so I unhooked the battery and the ECU and had the CEL and codes again as soon as I started it back up.

I decided to swap in my JWT ECU and had no CEL and even took it a few times up and down the street with no CEL.

So I'm beginning to think something is wrong with that ECU. I don't remember who I got it from, but it was from somebody on here and when it was shipped it was just stuck in a manila envelope and probably got hit and banged all through the postal system.

Guess I need to pick up another stock ECU. I can't pass emissions with the JWT

 

So I'm officially a moron. I had my Z32 on calipers on the wrong sides making my bleeder valves on the bottom side. Didn't even notice that when I was sticking them on. Switched the calipers and re-bled and all is good with the brake system. Don't know why I said brake booster in my earlier post I meant master cylinder. I even ordered a new master cylinder the other night before realizing my dumb mistake with the calipers.

Was able to drive the car a few times around the block with the JWT ECU and never got any CEL or poor performance. Later this week I'll try to swap in the stock ECU from the black VE and put some miles on it then go see how it does on the ole emissions machine.