Topic: 2007 Xterra Please Help!!

[Allbrant]

Hello. I have a 2007 Nissan Xterra . When I purchased it, it wasn't running, so I just rebuilt the engine. After putting everything back together It started up fine but I got a P0081 code and it was running rough. I disconnected the VVT Solenoid Bank 2 and it ran much better and smoother. I did the tests that the manual says to do and it seems like the white wire going to the ECM causes it to act up when ever I connect it to the ECM. The VVT gets the proper Voltage to and from it. I'm not getting timing codes just that P00081 Bank 2 Code. I disconnected the one on Bank 1 and no change in the way it runs. Only Bank 2 when connecting and disconnecting the white wire. Is that a problem with the ECM that is common?

[knightrider]

which terminal is the white wire on the plug for the VVT solenoid? normally white is 12v positive so that may be why you are seeing the issue when it is connected, because that is completing the circuit.

The code you are getting specifically states it only has to do with the voltage the ecu is seeing from the solenoid so it is most commonly a wiring issue, check the entire run for breaks or shorts (mice eating through wires, people messing with harness or old age causing the wires to crack)

Is the resistance of the solenoid within spec?  If the resistance is not within spec that will change the voltage that the ecu receives. 

Have you tried swapping the solenoid between bank 1 and 2 to see if the code follows the solenoid? 

If there are no issues with the solenoid or wiring then my guess would be there is an issue inside the ecu itself.  This is not a common problem to my knowledge.

[Celt]

which terminal is the white wire on the plug for the VVT solenoid? normally white is 12v positive so I would check for shorts to ground. 

The code you are getting specifically states it only has to do with the voltage the ecu is seeing from the solenoid so it is most commonly a wiring issue. (mice eating through wires or people messing with harness)

Is the resistance of the solenoid within spec?  If the resistance is not within spec that will change the voltage that the ecu receives. 

Have you tried swapping the solenoid between bank 1 and 2 to see if the code follows the solenoid? 

If there are no issues with the solenoid or wiring then my guess would be there is an issue inside the ecu itself.  This is not a common problem to my knowledge.

 That advice there was some Tarzan stuff! This forum always impresses me with the knowledge base here!

[Allbrant]

It's the wire that goes back to the ECM. The problem isn't only the code P0081. The problem is that when that white wire is connected it causes the engine to run rough like it's not timed right. Then I disconnect it and the engine runs smooth.

[knightrider]

You have one problem.  The trouble code P0081 is telling you what is causing your problem.  If the voltage the ECM gets is not correct, the intake VVT solenoid will not function correctly and will cause the intake timing on bank 2 to not be correct, thus rough running on bank 2.  You won't get any engine timing codes because the crank angle sensor does not see anything wrong, your issue is specifically on bank 2 intake cam, more specifically the wiring for the solenoid that controls the intake cam on bank 2. 

You have said you have proper voltage at the solenoid, what do you consider proper voltage?  Are you checking between the 2 terminals for the solenoid or did you check from pin 2(pin 2 is the left one when the pins on the plug are pointed towards you) to ground?  FSM wants battery voltage from pin 2 to ground. If you are checking between the 2 terminals you will not get a proper reading as the signal is a PWM signal, a multi-meter will not read this correctly. 

Are there any shorts on the wire that is going from the solenoid to the ECM?  What is the resistance of the VVT solenoid?

[Allbrant]

I'm getting 8.8 - 9 on the resistance between the 1&2 pins on the solenoid and while engine running at idle I have 14.3 on the battery and it fluctuates up and down on the power (#2 Wire Red) to the solenoid. Coming out of the solenoid (#1 Wire White) I also get around 14.3 and it fluctuates up and down.

[knightrider]

Pin 1 will fluctuate because it is a PWM signal so a multi-meter will not show correctly, only an oscilloscope will show correctly.  Pin 2 to ground should be whatever your battery voltage is, you should check it with the ignition on and engine off to get a stable voltage

the resistance on your solenoid should be 7.0 to 7.7 at 68* so yours is a bit high, I would try a new solenoid or swap the solenoid to the other side and see if the code follows the solenoid.