Hello , this is my first post here & am need of some guidance. I have an 03 Nissan 350z that I have been trying to diagnose an issue on. The car has loss of power top end randomly. Only noticable on the freeway. Also had a check engine light. I bought the car originally with a knock sensor code & the p0021 & I fixed the knock sensor code by finding a bad sub harness & my second code remained. I pulled the intake solenoid & applied power and yes it clicked operated as it should. I made sure to do the same for both sides just for extra comfort. I also cleaned both & had the same result. Swapped out the bank 2 solenoid with my buddys afterwards with the same result. I tested the harness for the solenoid and had 12v at the harness. I then did an oil change & still no change. I checked my camshaft sensors and they all seemed fine aswell as the crankshaft sensor. I swapped them out with my buddys working sensors aswell still same issue.
I read online about the oil galley gaskets blowing and indeed mine were blown. The upper gasket was in a couple pieces so I was certain that was my issue & changed the gasket but yet again continue to have the same check engine light aswell as random top end loss of power. I did anther oil change while I changed the gasket. I did do a compression test and got 180 across the whole motor. Timing Marks were all good when i checked them and spot on when I reasembbled. Pulled Valve cover & cams look fine nothing shown to be broken. Does anyone have any idea what i’m missing? My only possible ideas would be the intake cam sproket sticking or being bad aswell as maybe the ecu/ecm? anyway of being certain that either of those are bad ? i’d like to run some tests but am asking for guidance and reassurance before hand. can someone help me out? Thanks! I need to smog the car as soon as possible and this code is killing me !!

 

anyone?

 

Patience.....most people have other priorities on the weekends

 

anyone ?

 

Since you swapped out your IVT control solenoid valves with known good ones and the problem didn't go away, it would make me think that there's still some kind of communication problem between the valves and the ECU. You said you're getting 12V signal at the harness. Is the ground ok?

 

I don’t actually remember checking the ground at the connecter, let me do some research on checking the ground and i’ll get back to you, thanks!

 

can someone give me some guidance on how to check the ivt solenoid harness ? both wires! i’d like to know how to properly test it

 

The best way would be to use a bi-directional scan tool that allows you to activate/deactivate the IVT solenoids remotely. If you don't have a car computer that can do this (they're kind of on the pricey side,) then take the car to a dealership and spend the $100 on having a CONSULT II scan done. That will quickly gauge the quality of the connection between the ECU and the IVT solenoids.

 

so i’m currently looking for a shop with the proper scan tool but ran a quick test today and was wondering what you guys think. I unhooked the bank two solenoid and took it out for a drive and got the same results as if it were hooked up (random loss of high end power) . then after i manually activated the solenoid while the car was running by running power to the solenoid and the car indeed changed idle and pitch which gives me a good clue that the VVT gear is in functional order, doesnt mean its not sticking but just tells me that the gear is in a operation state. Could that possibly mean that something is up with the ecu/wires and how it triggers the solenoid to activate the VVT gear ? I will be hooking up a consult II to get a better test but was wondering what you guys think with what I came up with

 

anyone ?

 

That would be a logical conclusion: You're going to have to take out a wiring diagram and trace the power/ground/signal wires between the ECU and the VVT gear/IVT solenoids and then test the harnesses from each connection point. You can disconnect the battery and do a continuity check on each of the wires. After that, re-connect the battery and check the voltages and grounds. If there aren't any shorts in the wires, and if the voltages all check out, then you're going to need to have the ECU checked through an entire drive cycle, searching for glitches, since this issue is intermittent (assuming, again, that you're running with known good parts.)

I really do recommend you have your car hooked up to a CONSULT II and have a skilled technician look at it before you go through all that hassle though.

For a little background, are you the car's original owner? If not, how many miles are on the car, are there any mods and do you have a service history for the vehicle?

 

Again thanks for the detailed awnser, i’m still working on scheduling a time with the dealership since i am at work a lot hopefully sometime this week. My CEL actually went away and has not came back for more than 3 days so im certain the CEL is gone. I passed smog the 2nd day so all good with that. Still have random power loss but I actually just got the car and thankfully you reminded me about service history. I originally had a knock sensor and the over advanced timing code and i fixed the knock sensor code but the intake over advanced timing bank 2 remained. thinking about it now my knock sensor code was triggered due to the sub harness two wires grounding out with eachother so now i’m almost certain that it fried my ecu when those wires shorted together. after changing the sub harness my CEL went awayfor the knock sensor and the other code reaminrd. I finally got rid of the other code but i still have random power loss with no CEL. Do you guys think or have heard of the knock sensor subharness frying a ECU?

 

Hi friend Did you solve the issue of vvt selenoid bank 2?