P1320 Code 2001 QX4

[Pat2001QX4]

When I started my 2001 QX4 tonight after work, I noticed a small vibration in the engine. After driving for a few minutes, the Check Engine light started blinking. When I got home, I plugged in my code reader and found the P1320 code. I looked it up and came up with a faulty ignition coil. last spring, I had to replace the #2 ignition coil with the same symptoms and code. Is there any method to determine which ignition coil is faulty or do i need to replace all 6?

[VStar650CL]

On Nissan products from the millenial era, mixing and matching coils almost always causes issues. You might be able to fish out weak ones with a power balance test (and you can definitely spot one that's dead-missing), but I don't recommend screwing around with it. Hanshin, NGK/NTK, Denso, or Hitachi aftermarket coils are usually fine if you want to keep the cost down, but save yourself headaches and replace all of them with the same brand so your ECM has no excuse for confusion. Do a voltage drop test on your grounds, too. Crappy grounds are the biggest hidden killer of 3-wire COP coils regardless of manufacturer.

[Pat2001QX4]

I replaced all of my ignition coils & reset the P1320 code in my 2001 QX4. The vehicle runs much better (engine vibration gone & good acceleration) but the P1320 code came back after a short drive. No noticeable performance issues after the coil replacements, just the P1320 code Any suggestions as to what may be causing the P1320 code to come back?

[VStar650CL]

Did you check your coil grounds? Also, some DTC's can recur if you don't clear out the LTFT after repair. Can't recall if P1320 is one if those.

[Pat2001QX4]

What does LIFT stand for? I googled it and could not find a definition as it applies to DTCs. Also, through further testing, I can clear the code, start the vehicle, and it stays clear while I am driving. Once I turn the vehicle off and let it sit for a while, the code comes back when I start the car again. This happened twice.

[VStar650CL]

LTFT = Long Term Fuel Trim. It's a correction number gradually accumulated by the ECM based on the short term trims over time, i.e., whether your engine usually wants slightly more or slightly less fuel than the ECM's software "injection map" calls for. The code is likely a "2-trip" type which is showing up as "pending" the first time you drive and then changing to "current" and lighting the MIL the second time.

[VStar650CL]

PS - If your scanner doesn't have work support for clearing LTFT, pulling the MAF connector(s) with the car running to force MAF flatline codes (generally P0102) will automatically clear LTFT on most models. Once the code(s) occur, plug the MAF(s) back in, cycle the key, clear the MAF code(s), and you'll have a clean slate.