[Shep]

Hi Everyone,
I have an 05 350z (Non Revup) that I puchased the kit without cat for.
Everything went well with the install (tight fit). Ran good for the first couple of days; now I have an SES light on. I work at a dealership so I asked a few techs what they think. They pluged in a reader and said the codes are P1273 , P1284, P0300. The fist 2 are Air/Fuel Ratio Sensor 1? I'm assuming that these are the manifold o2 sensors? Am I assuming right? The P0300 is Random Misfire. I didn't change the spark plugs yet should I go 1 heat range colder? Would this cause this? Does anyone have any idea's as to what may be causing this? I've parked the car for now until I figure this out. The car has 33k on it and have never had any engine related problems. According to ALLDATA these codes (P1273/P1284) are a lean condition.. This is of BIG concern to me and must to resolved.

Any input is much appreciated
Thanks,
Shep

[Robert]

Originally Posted by Shep

Hi Everyone,
I have an 05 350z (Non Revup) that I puchased the kit without cat for.
Everything went well with the install (tight fit). Ran good for the first couple of days; now I have an SES light on. I work at a dealership so I asked a few techs what they think. They pluged in a reader and said the codes are P1273 , P1284, P0300. The fist 2 are Air/Fuel Ratio Sensor 1? I'm assuming that these are the manifold o2 sensors? Am I assuming right? The P0300 is Random Misfire. I didn't change the spark plugs yet should I go 1 heat range colder? Would this cause this? Does anyone have any idea's as to what may be causing this? I've parked the car for now until I figure this out. The car has 33k on it and have never had any engine related problems. According to ALLDATA these codes (P1273/P1284) are a lean condition.. This is of BIG concern to me and must to resolved.

Any input is much appreciated
Thanks,
Shep

Actually believe it or not the newer 350Zs/G35s have always had these codes pope. 1273/1284 are your O2 sensors yes but trust me you aren't running lean. Thats just the code they always pop no matter what the kit. Those codes are typically tripped by the rear O2s so I would verify the rear O2s are installed correctly. The 0300 code has popped on Zs even N/A before. It happens to every kit on any car. Its a side effect the ECU struggling to keep the larger injectors run properlly and keep the motor stoich at idle. The 0300 I wouldn't worry about too much. The the 1273/1284 are more of a nuisance as well but I would still verify the rear O2s are mounted correctly.

[Shep]

So what your saying in short is these are common codes and they aren't of concern what so ever? I have cleared the codes but they come back in less than 60 miles. At idle the engine does studder abit. This wasn't the case the first 150 miles of having the kit installed.

Thanks for the input
Shep

[Robert]

Originally Posted by Shep

So what your saying in short is these are common codes and they aren't of concern what so ever? I have cleared the codes but they come back in less than 60 miles. At idle the engine does studder abit. This wasn't the case the first 150 miles of having the kit installed.

Thanks for the input
Shep

These are very common codes for any boosted 350Z and even more so on the later models. The only one that concerns me at all is the 1274/1283 code as it might indicate the rear O2 sensors were not re-installed properlly. But even if it were not it would not negatively affect the performance of the car (or the safety of it) it would just mean the install wasn't 100% correct. Aside from that I have had the 0300 code for years now with ZERO issues as a side effect.

[Shep]

I appreciate the input so very much Robert!!!
But what about the engine stubbling abit at idle? It sounds like a miss. Should I change the plugs? If so should I change the heat range?

Also after talking to the techs here; they say according to the code and description "Sensor 1" this would be the sensor pre-cat. Is this correct, you are stating it's post-cat. Maybe the description I have is incorrect.

Thanks again,
Shep

[Robert]

Originally Posted by Shep

I appreciate the input so very much Robert!!!
But what about the engine stubbling abit at idle? It sounds like a miss. Should I change the plugs? If so should I change the heat range?

Also after talking to the techs here; they say according to the code and description "Sensor 1" this would be the sensor pre-cat. Is this correct, you are stating it's post-cat. Maybe the description I have is incorrect.

Thanks again,
Shep

Its reading that code because the rear O2s are not correcting as they should because your cats are gone. Trust me. i had these codes at first then Turbonetics updated the downpipe to add an extension which made the code go away for me. But some of the late 04s and 05s the codes came back for no reason and I know its happened on other kits as well. As for the stumble at idle mine does this from time to time. Nothing major and the car runs very well under boost and load which is important. I switched to NGK one step colder plugs and the stumble got better but its going to be a little rough at idle as the ECU has a tough time correcting the fuel for stoich with 380cc injectors in there. FYI the code description should say something like Bank 1 and Bank 2 meaning driver and passenger side bank. Not the first o2s...

[Shep]

Thanks again Robert!
I must say that I've withheld some info regarding the o2 codes. I did this not to be a jerk but in efforts to avoid getting a biased or automatic reply. Not saying that this is what you would do, but a lot of times people will just say it's something you did rather than think about the actual cause. The post cat o2's were installed correctly but later I moved 1 to the end of the I would call the intermediate pipe where there were 2 unused o2 ports. In order to do this I cut the wires on the o2 sensor and extended it to reach. I did this so I could in its original position install a wide band sensor and get a more accurate reading for monitoring A/F. I'm assuming here I've ruined the sensor and will probably need to replace it to get rid of the o2 codes. The only thing I can think of; that is by extending the wires probably changed the resistance of the sensor... Now will this in the mean time make a lean or add risk to running the car like this? This being the post o2 sensor I don't believe can cause a lean condition but I don't know for sure. If the SES light is on does this cause the ecu to run in a different mode?

I appreciate your input!!!

Shep

[Robert]

Originally Posted by Shep

Thanks again Robert!
I must say that I've withheld some info regarding the o2 codes. I did this not to be a jerk but in efforts to avoid getting a biased or automatic reply. Not saying that this is what you would do, but a lot of times people will just say it's something you did rather than think about the actual cause. The post cat o2's were installed correctly but later I moved 1 to the end of the I would call the intermediate pipe where there were 2 unused o2 ports. In order to do this I cut the wires on the o2 sensor and extended it to reach. I did this so I could in its original position install a wide band sensor and get a more accurate reading for monitoring A/F. I'm assuming here I've ruined the sensor and will probably need to replace it to get rid of the o2 codes. The only thing I can think of; that is by extending the wires probably changed the resistance of the sensor... Now will this in the mean time make a lean or add risk to running the car like this? This being the post o2 sensor I don't believe can cause a lean condition but I don't know for sure. If the SES light is on does this cause the ecu to run in a different mode?

I appreciate your input!!!

Shep

Quite frankly what you did should not be causing an issue with the codes. I did this before with a prior car to move the secondary O2 behind the only remaining cat on that car. Its not enough to cause the issue. The root cause of the issue is the the 04.5-05 ECU and later are much more intelligent then prior models. It detects the the rear O2 sensor is not changing condition from lean to rich in the appropriate amount of milliseconds as the cat is no longer there and causes these codes to occur. The only O2s that actually matter on this car are the ones that are or used to be in the manifolds. The passenger side one should still be in the manifold and untouched. The drivers side manifold sensor gets moved to the feed pipe to the turbo. The two rear O2 sensors that used to reside behind the cats should have been the two moved to the location on the downpipe where the extenders are. As long as one of the two rear O2 sensors is the one you cut it should not be an issue. As I said these codes are mostly a nusance. They cause no adverse affects on the tune of the car and do not change the operating map of the ECU whatsoever. The only negative side affect is the light. I've lived with mine (result of the 0300 code) for over 2 years. Never had one issue.

[Shep]

Thanks very much Robert for your input....

One other question for ya though... What difference does the plenum spacer make? Can this be done without needing another reflash?

Thanks,
Shep

[Robert]

Originally Posted by Shep

Thanks very much Robert for your input....

One other question for ya though... What difference does the plenum spacer make? Can this be done without needing another reflash?

Thanks,
Shep

Shouldn't cause much of a difference. I and others have run plenum spacers with no changes to the flash and no issues.