Swaglife81

I had the dreaded VDC,Slip,SES light with code P0121 and the new throttle body fixed that issue today. Awesome, so knowing how ECUs adjust I reset everything.

Battery disconnected during TB install
Pumped brakes 2-3 times to motivate ECU reset
Reset ECU
Warmed car up, no codes
Idle and everything was perfect but went ahead with Pedal, TB, and Idle resets and everything took as it should.
Car idles at a perfect 650 all day
Runs better than it ever has, only had the car 7 weeks and been apart half that time
Last reset the fuel mixture self learning control, whatever the true title for it is. I reset the Fuel Trims
At idle in closed loop warmed up in between 185-199 degrees my LTFT on banks 1 and 2 are reading 9.4 steady.

I get good MPG on the highway, OBD2 at 55-65 mph was showing 27-29MPG. I'm under the impression LTFT and STFT should be close to zero optimal and maybe a tad -2 or so. After all the resets it's sitting steady 9.4 LTFT on both banks which I can't assume is a mechanical issue that would be impossible. The car is a 03.5 G and no maintenance records in the factory Infinity books that are still in the car. I have no idea if the car has ever seen Consult 2 or a tune.
All sensors are reading perfect, MAF, coolant, O2's at idle are reading 0.1 to 0.3.

So am I ok, far as I know the car is stock visibly. Could I have a car with a tune on it but with stripped mods for a almost even 10% rich LTFT after warm and air/fuel reset. No vacuum leaks, I had bad valve cover gasket leaks but fixed that about 5 days ago.

venture210

If your car was previously tuned for bolt ons, it would very likely be running richer with all of the oem parts re-installed. If you are trying to get your AFR's in check, you'll have to reflash your ECU back to stock more than likely. If the ROM is tuned to run the engine with basic bolt ons, you should only be running very rich under wide open throttle where the ECU is running in open loop. For closed loop (idle and cruise) it should be running just fine becuase the ECU will learn to compensate the for the target AFR which explains the good gas mileage

Swaglife81

Good to know, I know I'm not just being paranoid. It's not the easiest to track down the previous owners and buying a used car you never know. The thing is, the car feels stronger than my v8 03 mustang gt, I bought that car new. So a tuner or Infiniti are the only ones who could tell me what is going on in the ECU right. No way on my own to confirm? I do plan to add the basics this month, MD spacer, exhaust, the typical bolt ons. Guess if the air fuel leaned out more normal I would know than. The front fenders have been rolled so the car has been tinkered with at some time. People don't do that for know reason

Swaglife81

Just want to get an update because I'm trying to get this car back to perfect. The main problems I have fixed. Throttle Body replaced because of TB Actuator code, bad leaking valve cover gaskets and intake coupler leak. So you can imagine this improved the car. This is all going back to 2 weeks ago but an update on my OP concerning Fuel Trims.

Today datalogging in real time, just eyeballing all the sensors at idle especially. Both 02's on bank one were reading .00 but this was rounded up to the tenth. My fuel trim is off on bank 1 but no codes are being thrown. Its rich on that bank showing a constant 10% plus LTFT. Both banks will stay at 9.4 usually. But back to bank one O2 sensors, they have always read .1 up to .8, .1 at idle low RPM's mainly. Except today .00 for at least 5 minutes at idle. Now I'm not sure what to look at since this is both sensors on that side. I did a wire tuck when I did the valve cover and intake gaskets and checked every single wire and sub harness for any signs of anything damaging. Again everything seems great at part throttle or WOT from what I can get out of it. When I pulled the intake plenum off all 3 cylinders on that side in the intake manifold were black, while the other 3 on bank 2 were clean as can be. So I know this isn't a recent issue or something I did wrong because Ive been working on dialing in this car in stock form before I mod it. I guess I could swap O2 sensors on each side and see if the issue swaps banks or maybe even swap injectors to each side. Or than that with no codes being thrown or even pending I'm at a loss. I have no idea to tell if my ECU is re-mapped but I do know its the older ECU that requires re-pinning or a piggyback and I know there is no piggyback on it right now.

I understand one of these posts isn't the fun I got a Turbo kit or full SPC suspension but there isn't much activity on the other message boards

Swaglife81

Found my problem. Eyeing my fuel trims daily I noticed they were switching sides or going 25% positive on both banks but only at idle I knew it was a vacuum leak somewhere.

Turns out the vacuum line I replaced about 2 weeks ago from AutoZone is to big so the non adjustable clamps won't tighten it down enough, you can't hear the leak. Obviously since this was a new vacuum hose I was looking elsewhere. Touching the hose creates a hissing sound. Bam found my leak. This is why it's sometimes, and worse at times, the hose is almost perfect but a tiny amount to big in inner diameter and probably a tiny amount to small in outter diameter since the non adjustable clamps aren't tightening it down. I ziptie each end as tight as I could to lessen the leak.

The vacuum line in reference is from the back of the Plenum into the evaporator solenoid. When doing my valve covers this hose broke and was replaced. So now I need another one. I relocated my evap solenoid and a longer hose was needed. So now can someone tell me the size I need and best clamps to use for a vacuum hose. Factory isn't doing because of O.D.. I imagine AutoZone guy just eyeballed it assuming it was gonna be tight enough. Not the easiest Inner Diameter to find on this hose.