Alright so cruising down the highway, my Z's SES light came on, pulled to the side checked my MAF connections and all the lines I could see and everything was fine. Didn't feel any loss of power or any weird effects so I drove home.

Next day on the way to the shop to get the codes ran, the car was acting really buggy. It drives normally up until 3200-3500 rpms and then just doesn't move. Like the rpms will rise very slowly even though I'm fully pushing down the throttle.

Pretty much I lose alot of power and the rpms go up really slow, but then sometimes it will go back to normal and then get messed up again.

The codes that came up were P0327 for the knock sensor and the other code was for the bank 2 o2 sensor.

Nothing else is wrong with the car, never had any issues. Car idles fine, sounds healthy, no leaks, nothing seems wrong other than the random loss of power.

It's a 2003 Touring model and I just hit 90,500 miles.

Only mods on it are the JWT popcharger and a megan racing single exit exhaust.
Used to have test pipes, that could be the reason for the o2 sensor going out but it's on stock cats now.

Need opinions on what could be the main cause of the power loss because I'm read a couple threads on which the knock sensor codes are sometimes "ghost codes"

Thanks!

 

Usually when you get a knock sensor code it is in fact a bad sensor or the sub harness going to it. You need to get readings off of all 4 O2 sensors in order to try and figure out if they're ok or not.

 

Alright cool, but does a faulty knock sesnor explain the weird power loss thing I'm having?

 

No, but you have the code for an O2 sensor. A bad knock sensor will make the car sluggish from idle to about 4,000 rpm.
I see you have a pop-charger too, maybe you should clean the MAF with some MAF cleaner since they can get oily from the oiled filters.

 

Did you buy the car used or new? If it hasn't happened yet, at 10 years old with 90K+ miles on the odo, it probably needs a tune-up more than anything else. Fouled plugs/injectors could be causing combustion issues that are getting picked up by the knock sensor and a rich condition can ruin your O2 sensors. The knock sensor can be tested but requires a tool that can replicate the proper sound frequency to produce a voltage output signal. The O2 sensor can be easily tested (just google O2 sensor testing.) Don't throw new parts at the car without testing the old parts first.

If the car hasn't been tuned (spark plugs, filters, check coils, check fuel injectors, run a full diagnostic scan, etc.) then now's the time. This is easy enough to do if you have the right equipment, but can be a nightmare if you don't. In the end, a trip to a qualified shop might be your best bet. I've spent $thousand$ on diagnostic equipment, so I'm fine doing the work myself. I don't know what your level of expertise is with projects like these, so I can't assume you know what you're doing. However you decide to proceed though, best of luck.

By the way, it sounds like you're car is running in limp mode right now, so whatever you do, do it soon.

 

Did you clean the MAF yet? Also...how many driven miles are on the cats? Could be clogged

 

It's funny how easy it is for me to fix my own vehicles, but other people's problems require a completely different approach. It all starts with a thorough description of the symptoms.
If you have a knock code, the chances of it being the knock sensor or the sub harness are very high. Unfortunately, you'll need both parts plus an intake gasket set to do it. I would suggest getting a proper diagnosis from a reputable shop before buying any parts.

 

Sweet, I was thinking about doing a complete tune up anyways. From sparks to differential oil.

I was planning on doing the fix myself and everything, just wanted to see what else would cause this.

Thanks!

 

Agreed. It's hard to assume that people are capable of using the information you provide to them when they seek help on the internet. I'm all about diagnosing the problem in proper order by following the FSM troubleshooting guide until the evidence dictates what type of repair is required. So many people would think, "Oh a knock sensor code - it must need a new knock sensor," when that's simply not the case.

The biggest frustration is when a person who needs help doesn't follow the guidelines in the sticky on how to report a problem (this doesn't necessarily apply to this thread, OP.) They'll say something's wrong with their car but they won't tell you about the hack job they did on their exhaust system or the time their car was submerged in four feet of water.

In order to make an educated guess on where to begin, we need (at least) the following:

1. Year
2. Mileage
3. AT/MT
4. Modifications
5. Maintenance/repair/accident history
6. Purchased new or used (i.e., do you know everything that's been done to the car since it came off the assembly line?)
7. A complete, legible description of the issue
8. Has the car been looked at by a mechanic already and what did they say?
9. What are your capabilities to repair the vehicle (i.e., access to proper tools, including specialty tools, diagnostic equipment and time; do you need your car for work tomorrow?)

It only takes 10 minutes or so to put that information together, but it helps us make more than simple, educated guesses with regard to potential fixes.

 

[*]Year - 2003[*]Mileage - 90,700[*]AT/MT - MT[*]Modifications - JWT popcharger, 5/16 spacer, single exhaust.[*]Maintenance/repair/accident history - very well maintained from first day[*]Purchased new or used (i.e., do you know everything that's been done to the car since it came off the assembly line?) - Used with 40k miles, have all service records and what not from first owner (older gentelman who babied the car)[*]A complete, legible description of the issue - already explained.[*]Has the car been looked at by a mechanic already and what did they say? - yes, everything seems fine except the knock sensor.[*]What are your capabilities to repair the vehicle (i.e., access to proper tools, including specialty tools, diagnostic equipment and time; do you need your car for work tomorrow?) Not a pro mechanic, not a monkey either. Done a lot of work on cars myself, know how to get around them. I have tools, from basic to specialty ones, can have access to a shop if needed too.
Have another car, so the Z can sit.

 

I would just plan on changing the knock sensor, sub harness, and intake gaskets, it's a common problem with many Nissans.
If the knock sensor and harness don't fix the p0327 then you have a wiring issue somewhere beyond that.....which is highly unlikely.

 

Yah, i'm going to order the knocksenoer/subharness from z1 and swap them out see if it goes away, thanks for the help!

 

Watch the video, then check the sensor. It could save you $50 bucks on the sensor alone. If the sensor's busted then hey, at least you know. It only takes a few minutes. Did you already get the FSM from the nico site or do you need the link?

 

informative video, learned a couple new things but the problem is, the Z's knock sensor is not that easy to get too. I might as well just change the whole sensor and harness since I have to take apart the plenum, runners, and whatever. Not worth it to just do all the work and not change the part (in my opinion) code has been coming back enough to make me WANT to change the part regardless if it's broken or not! the link would be nice, thanks!

 

....Just do it already. FYI the sub harness plug can be tricky to disconnect, and don't forget the intake gaskets.