what's up guys I have a 2004 g35 coupe 6mt my short term fuel trims are pinned at 99.2% on both banks so far I've fixed every vacuum leak I have replaced both my upstream and downstream o2 seniors with denso. I have reset/cleared the fuel ratios and I have also replaced the Injectors along with spark plugs. the only code that comes on is p1283 air fuel ratio sensor 1 lean shift monitoring bank 2 this is after I did everything mentioned up above also new cats and new exhaust with zero leaks car has about 135k on it it does burn a f*uck load of oil.i just did the fuel injectors today and drove about 50 miles so far no check engine light but the fuel trims are still at 99.2% on both banks. also sometimes on first startup I would get a misfire that would eventually clear up.

 

I think the fuel trim can only go to +/-50% for LTFT. What tool exactly are you using to check, are you checking LTFT or STFT?

 

both my Snapon edge and autel scanners

 

What data are you seeing on the sensor 1 O2 sensors?

 

for both upstream o2's im seeing 99.2%

 

Does it change at all when you stomp the throttle WOT and quickly release? It should lean shift quite a bit of watching real-time data. If it doesn't budge I suspect the O2 sensors are messed up.

Also when you stomp the throttle when driving is it pumping out really black smoke?

You might take off the cats and inspect for damage/melting too. See how it runs catless for a few minutes just to rule out exhaust problems.

 

How does it FEEL that's it's running during a drive?

 

 

Ok I see what's going on, those are NORMAL values. There is no sensor 2 short term fuel trim so the scanner is just trying to fill the box with SOMETHING, you can ignore those values. Everything looks normal though, you're still throwing that code?

I would pull and inspect the spark plugs, that will tell you EXACTLY what the conditions in the combustion chamber is like, post pics. If you're getting a lot of oil in the combustion chamber it's going to foul out the plugs faster and you might have to shorten up your maintenance interval to compensate. Did you use NGK PLFR11-5 plugs?

If the code is still popping up I would first verify you don't have a leaking bank2 header, then double check the gasket between it and the bank2 cat to make sure it's still intact..

 

That makes me feel alot better lol but i cant remember what spark plugs i used i may still have the recite in my toolbox at the shop i pulled cylinder 1s plug the other night didnt look fouled out

 

Hard to tell from the photo but the center electrode looks like it's worn out of spec by normal usage. You should use a gapper or feeler gauge to make sure it's still gapped close to 0.043 inch. I'm guessing you use some kind of fuel additive? The deposits don't look too bad but definitely looks like some kind of additive is being used.

 

Yea i use techron with the oil changes im gonna order a set of ngk’s but you sure the fuel trims look normal?

 

Yeah the STFT looks fine, it's not giving a valid reading for LTFT so you might look around a bit more and see if you can find it. The CEL doesn't turn on until LTFT hits +/-25%. STFT fluctuates significantly and you're on/off the throttle under various loads so you basically use it for a reference when troubleshooting other issues.

My LTFT usually sits at about +12-14% it's how much of a baseline fuel multiplier is needed to compensate for things like vacuum leaks, injector clogging, etc. When you do an ECU reeset it puts the LTFT back to zero and the computer makes adjustment as needed.

STFT is a fast-acting trim for when you're climbing a hill as opposed to rolling on a flat highway, mashing the throttle and needing a little more gas than the baseline programming, it's more of a "1 second or less reaction time" to A/F trim.

If you mash the throttle then quickly let off your STFT will fly all over the map.

 

After 160 miles code came back again p1283 think its going to be the cats and that means time for downpipes and a tune

 

Models:
2003 Infiniti G35 Sedan
2004 Infiniti G35 Sedan
2005 Infiniti G35 Sedan
2006 Infiniti G35 Sedan
2007 Infiniti G35 Sedan
2008 Infiniti G37 Sedan
2009 Infiniti G37 Sedan
2010 Infiniti G37 Sedan
2011 Infiniti G37 Sedan
2012 Infiniti G37 Sedan
Mixture Ratio Self-Learning Control
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from air fuel ratio (A/F) sensor 1. This feedback signal is then sent to the Engine Control Module (ECM). The ECM controls the basic mixture ratio as close to the theoretical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as originally designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic changes during operation (i.e., fuel injector clogging) directly affect mixture ratio.

Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This is then computed in terms of "injection pulse duration" to automatically compensate for the difference between the two ratios.

Fuel trim refers to the feedback compensation value compared against the basic injection duration. Fuel trim includes short term fuel trim and long term fuel trim.

Short term fuel trim is the short-term fuel compensation used to maintain the mixture ratio at its theoretical value. The signal from air fuel ratio (A/F) sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the theoretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich, and an increase in fuel volume if it is lean.

Long term fuel trim is overall fuel compensation carried out long-term to compensate for continual deviation of the short term fuel trim from the central value. Such deviation will occur due to individual engine differences, wear over time and changes in the usage environment.

Instructions
1Start engine and warm it up to normal operating temperature.
2Turn ignition switch OFF.
3Disconnect mass air flow sensor harness connector, and restart and run engine for at least 3 seconds at idle speed.
4Stop engine and reconnect mass air flow sensor harness connector.
5Make sure Detected Trouble Code (DTC) P0102 is displayed.
6Erase the DTC memory.
7Make sure no codes are stored in the ECM.
8Run engine for at least 10 minutes at idle speed.