Nissan Xterra problems need help pinpointing the problem.
 

I'm trying to help my aunt out, her xterra cranks longer than normal before it starts, has code p0345. I've replaced both cam sensors and the crank sensor, as well as doing a full tune up. Once it starts it runs fine just cranks for a while then finally starts. I'm hearing it could need a time chain replacement but I'm highly doubting it being as it runs fine and doesn't miss or have any chain slap that I can tell.

It's a 2008 Nissan Xterra, 4.0 2wd with just under 80k miles. Thanks in advance

Re: Nissan Xterra problems need help pinpointing the problem.
 

Okay, you've said something very interesting that I think points to the real problem. It cranks longer than normal, and has code P0345 (cam sensor, etc). You've replaced all the important sensors, which only really leaves a few suspects in the sensor circuit, like a harness problem or an ECU problem, neither of which are likely if the car is stock and has <80k miles.

But, a slow engine start because of a bad starter, weak battery, bad ground or power connections, etc., can cause a false cam position sensor (or crank sensor, depending on start/run transition strategy in the ECU) fault. The ECU gets confused when it's seeing crank sensor signals and isn't seeing cam sensor signals when it expects to, either because the sensor voltage is too low or because the crank fluctuation is too high (the crank acceleration can change a lot during engine start). Remember that the cams are driven at half of the crank speed, and the cam position encoders usually have a lot lower angular resolution (less teeth) than the crank position encoder.

That's a lot of the reason why the USDM ITR has an extra crank fluctuation sensor that the JDM ITR doesn't; fast, accurate engine starts mean an incremental improvement in emissions.

So look at what the battery voltage is doing during the engine start, and see if you can uncover anything there.

I don't know much about Nissans specifically, but this is all standard engine theory based on the type of problem that you're seeing.

Re: Nissan Xterra problems need help pinpointing the problem.
 

Thanks fabrik I'll look into that.

Re: Nissan Xterra problems need help pinpointing the problem.
 

Tested the battery before and during cranking, before it was 12+ volts, as soon as it was started it dropped to 10 volts. I had both battery and starter load tested but both passed, that or autozone's load tester sucks. I'm going to try swapping the battery this evening and check all the grounds

The stupid idiot at autozone said oh you should replace the fuel filter so I just shook my head and left

Re: Nissan Xterra problems need help pinpointing the problem.
 

Did you replace the cam sensors with, Nissan sensors or did you get aftermarket sensors? The reason I ask is because a lot of maxima guys have issues with aftermarket cam sensors.

Re: Nissan Xterra problems need help pinpointing the problem.
 

Oem replacement sensors from autozone

Do the sensors have the metal sleeve? I had the same problem with an Altima and found that Nissan had revised the sensor. I picked it up from the dealer and problem was gone.

Re: Nissan Xterra problems need help pinpointing the problem.
 

Metal sleeve over the sensors body? If so no

Re: Nissan Xterra problems need help pinpointing the problem.
 

I am not familiar with what cam sensors an xterra uses but I am very familiar with a Nissan maxima, and the aftermarket ones are junk. Yours may be fine, but they are know to cause problems on maximas.