2012 Pathfinder MAF

[jerrylicarie]

Hi all. Just joined. Happy to be here. My 2012 Pathfinder 4.0L has been throwing p0101 code randomly for a couple of years. No drivability issues at all, until three months ago. I've had three instances of poor acceleration, hesitation and abnormal idle in the last three months. In all three cases it has cleared up after shutting down and restarting engine. I'm aware of a TSB for the p0101 with no drivability issues calling for an ECU programming but have not opted to have done. It drives very well and has its usual 17 mpg with exception of the three incidents. During the last incident I was able to gather some live data and my short term fuel trims for both banks was all over the place between -25 and 25. I have a new air filter. I have checked for vacuum leaks and air intake leaks and found none. I have an identical 2011 Pathfinder and will swap the MAF's but with the infrequency of the performance issue, it may take some time for conclusive results. Hoping this long winded description might help in some much needed advice. Thanks in advance.

[VStar650CL]

Try cleaning the Throttle Body and then performing an IAVL on the MAF. Check your PCV Valve also, if there's any oil in between the airbox and the TB then replace it.

Swapping MAF's is a bad idea unless you do an IAVL each time, otherwise calibration is off and you're not proving anything.

[jerrylicarie]

Thanks for the suggestion, VStar650CL. Is there a simple procedure for IAVL that doesn't require specialized scan tool? I was going to clean throttle body, but was hesitant because of re learn process. I also have a new PCV ready to install.

[VStar650CL]

There's a manual procedure on EC-26 here...
https://www.nicoclub.com/service-manual ... 2%2FEC.pdf
...but it's very stilted and finicky. The CVTz50 app actually has an IAVL utility that other people tell me will work on R51/D40/N50's even though they don't have CVT tran-nies.

[jerrylicarie]

Thanks again for that. Not sure I want to crack open that can just yet. Just don't see why it happens so infrequently. I've looked at weather, temp and drive times each time. The only constant is it was on Nov, 28th, Dec. 28th and Jan. 28th. Twice it was after a prolonged warm up period. Thought it might have been restricted cat as I was also having a p420 code long before this. Had replaced bank 1 front cat with aftermarket previously when original had a weld failure on the outlet tube. Replaced again a month ago. No restriction in one I removed and no more p420. Just left scratching my head. Trying to avoid dealer. May just buy a genuine Nissan maf and put it on myself then bring to dealer for relearn/reprogram and any other diagnostics.

[VStar650CL]

P0101 is a hard nut to crack because it's a "catchall" that the ECM uses for any induction problem which it can't figure out. So although the descriptions says "MAF", it's never a bad MAF which causes it. Dirty MAF, yes. Dirty Throttle Body, PCV not sealing, airbox leak between the MAF and TB. On a 4-banger sometimes a bad A/F, but on a V6 you'd be getting a bank code. The ECM repro is actually for that, the original "A/F window" in the ECM firmware is too tight, and aging components can cause the ECM to think there's a problem when there isn't one. The repro expands the window parameters.

[jerrylicarie]

Agreed! My problem with the dealership is I can guarantee the first thing they will do is replace the MAF for twice the price. Then, when it doesn't work, the rabbit hole opens. I need to find a good diagnostics mechanic with the proper tool.

[jerrylicarie]

Looking closely at pdf you sent, it looks like I could benefit from EC-86, specification value.

[VStar650CL]

The spec isn't actually worth much where the MAF is concerned. In general the reading at idle in g/s will be a bit more than the engine displacement in liters, e.g., a healthy QR25 will usually read low~mid 3's in g/s. However, that's a calibration-dependent value and being in the ballpark doesn't mean it's correct. The purpose of IAVL is to put the MAF, TPS, and APP all on the same page in the ECM's memory, which they need to be for the induction to work right.

[jerrylicarie]

Makes sense. Gonna go ahead and replace PCV valve and bring in for throttle body and intake cleaning followed by all the necessary IAVL procedures.