Hey there!

I recently made a post about all of the various repairs done on my 1998 pathfinder. I still have not discovered the cause of the main problems on this vehicle. To recap, I replaced all of the injectors with beck and Arnley (and 1 rare hitachi I found new). I tested the fuel pressure regulator by attaching a hand pump to the vacuum line and pumping it up to factory engine pressure specks. This held engine vacuum without wavering. I also replaced all of the vacuum lines in this vehicle, and the IACV. The EGR system has been tested and works fine (not throwing codes or leaking). The front heated O2 sensors and the driver’s side exhaust manifold has been replaced.

To get down to the issue, my car struggles to start on any sort of incline or decline. I usually have to use the throttle in order to get it started. It runs rough immediately after starting and will throw a solid MIL with a P0300 code. I took fuel trims and they land like so:

STFT B1: -5.5 to -19.5% ( with -15.6% being at idle at -5.5 being raised up to 2000 rpms)
LTFT B1: -10.2%
STFT B2: -5.5% to .8 % (with -1.6 at idle and .8 at 2000 rpms)
LTFT B2: -9.4% to -7.8% (with the value becoming -7.8% at 2000 rpms)

Additionally, the OBD-II scanner I’ve been borrowing from O’Reilly’s occasionally says that I have an OL-fault in my fuel systems. Not sure if that will help, but I thought I would add it. Plus, I’ve noticed when I go back to my hometown, which is 1000 feet lower in elevation than where I currently live, my fuel trims are also MUCH closer to 0 on both banks and go as follows;

STFT B1: -10.2% (this value changes constantly with some values being slightly positive (3.9%).)
LTFT B1: -10.2% to -6.3% (mainly stays at -10.2% with brief rises to -6.3%)
STFT B2: 0%, 2.3%, 4.7%, 1.6%, -3.1%, -6.3%. This value, like the other STFT, is highly variable. This one more consistently stayed positive than the other bank.
LTFT B2: .8%, 7.8%, 8.6%, back to 7.8%. These values fluctuated along with the STFTs when I raised the rpm’s to 2000.

Does anyone have any ideas as to what could be causing these highly negative values? I know injectors are usually the culprit, but having replaced them all with good brands, I would be surprised if they went bad so soon. Especially because they all clicked with a 9v and fell within factory specs for the ohms. Any help is appreciated! Thanks!

" someone " put " SOMETHING " in your GAS TANK ? ?

Unbeknown'st to YOU of course..............in all due respect ........................RESPECT !

pick-up screen that is ................pickup-screen problem , ya ?

Trooper329 wrote: ↑

Wed Aug 23, 2023 8:02 am

Does anyone have any ideas as to what could be causing these highly negative values? I know injectors are usually the culprit, but having replaced them all with good brands, I would be surprised if they went bad so soon. Especially because they all clicked with a 9v and fell within factory specs for the ohms. Any help is appreciated! Thanks!

Double check the injectors for leaks with a fuel pressure gauge. With the key On and engine Off the pressure should be about 40psi. Pinch off the fuel input line to the gauge. If the pressure drops, your injectors would be suspect of leaking from the gasket seal(s) or the injector(s) is flowing fuel when they should be closed.