Hello,

I have a 2005 350z that is set up for drifting. It is currently throwing P1148 and P1168 (02 closed loop bank 1 and 2 sensors) codes as well as P1031 (AFR ratio sensor meter).

Car was drifted at an event without issue. Sat in the garage for a few days, then driven 30 minute twice.
On the way there, car felt a LITTLE funny, something that could easily be brushed off. On the way back, car progressively gets worse, misfires with loss of power and CEL flashing.

Oil on spark plugs. Replaced spark plugs and valve covers. No oil on spark plugs.

Car continues to idle poorly, but under normal RPM and always starts right up. Can rev to redline without issue but ONLY IN NEUTRAL.

Under almost any gear under almost any acceleration, car misfires badly and CEL will flash.
I've tried basic stuff like cleaning MAF sensor, unplugging coil packs but engine has ~95k miles and most things were replaced ~10-15k miles ago.

All 02 sensors read at .28 except bank 1 precat at .6, but research I've done leads me to believe that 02 sensors rarely fail.
I can live data I can post if that would be helped as well. MAF seems to work find and air/rpm is linear.

Any help in the right direction is appreciated. Thanks so much!

 

Oil on plugs is never a good sign (When you say "on plugs", I assume you mean the electrode in the combustion chamber, not the plug wells and coil packs). Double check your PCV system, make sure it's not blocked up. It's possible your Z was burning an excessive amount of oil which could lead to premature failure of your O2 sensors and CATs. The high RPM demands of drifting will exacerbate oil consumption or PCV system faults. What mods have you done concerning the engine? Based on the information provided, I recommend taking the Z to a shop with experience on these cars. It's not uncommon for higher mileage Zs to start experiencing missfire issues related to CAM and CRANK position sensors failing, however different codes are usually thrown in these cases. This could just be a simple sensor problem, but you don't want to start throwing parts at it without a proper diagnosis.
-Icer

 

if the CEL is blinking, that is a cat damaging misfire. meaning I would focus on spark. do you have the FSM to follow the diagnostic trouble tree for those codes?

 

The MAF would cause these issues and you are getting a code for it

 

Thank you all. The car never burned a significant amount of oil. The car is straight piped with a CAI and ECU is tuned. Cam and crankshaft position sensors have been replaced recently and symptoms seem atypical for those sensors.

FSM? I am unfamiliar with this abbreviation. The car has no cats.

I have cleaned the MAF sensor and checked the lb/s of air which rise linearly and seem to be within normal parameters.

I will check the PCV system over the weekend. I can upload live data if needed. Thanks everyone so far!

 

Hi Zack,

If the vehicle has no cats, I would imagine that's your problem. What test pipes are you running? You will most likely need to trick the ECU regarding the O2 sensors, was this accomplished during the Tune?
-Icer

 

I bought the car with the tuned ECU and current exhaust set up.
Nothing has been changed or modified to the engine relating parts (intake, exhaust, ecu, etc) since I have owned the car. This problem has only happened recently out of the two years I have owned the car.

 

Understood. Btw, FSM refers to Factory Service Manual. Downloadable pdfs used to be hosted on the NICOclub forums, however Nissan issued a cease order over their intellectual property.

Since you don't have cats, I would look into how the cat O2 sensors are being handled (is there something connected up to the sensor plugs? or are the O2 sensors present and connected up to the test pipes? For example, the Motordyne ART pipes use the factory sensors in a way that doesn't throw codes for most people). Also, as Tomek suggested you may have a missfire issue related to the ignition system. This could mean 1) Bad Spark plug(s), 2) Bad Coil Pack(s), 3) Bad fuel injector(s), or 4) Wiring or computer fault.

You mentioned the cam and crank sensors were recently replaced. Did you use OEM parts or aftermarket? I ask because nearly everyone who has used aftermarket (O'Reilly, autozone, etc) sensors has either had the issue come back after only a few weeks or months, no change (issue remains), or the problem gets worse! In summary, use OEM when it comes to cam and crank sensors on these cars.

Lastly, if you are not experienced with troubleshooting fuel injected engines, I suggest having a shop take a look.
-Icer

 

P1148 and 1168 are closed loop failure. This means that the ECU is getting no data from either of the primary O2 sensors, which it uses to control the fueling. Either the sensors are dead, there is a problem in the wiring, or you blew a fuse. This is the root of all your other problems.

P1031 is for the bank 1 primary O2 sensor, similar to the 1148. This is not a MAF code.

None of these are cat inefficiency codes and have NOTHING to do with your exhaust set up or cats/ no cats.

 

Thank you all. There are only two 02 sensors on the car.

I have swapped the 02 sensors to opposite banks. The car runs the same but O2B1S1 (V) used to run at .3 but now fluctuates with live data from 0.18 to 0.22 at idle as RPMs change. The idle seems more abnormal and fluctuates more frequently (I think).

02B2S1 (V) is still at .620 and others are still at 0.28.