PO171 code hell 2004 tacoma

Hi everyone, I've been trying to figure out why my 2004 Tacoma 3.4L V6 keeps throwing the P0171 code. I brought the truck to a mechanic who wasn't much of any help. They did say they smoke tested it and that it was negative for a vacuum leak. They also cleaned the MAF sensor... Anyway, they charged me what seemed like a ridiculous amount ($200) so I'd much rather attempt to diagnose this myself if possible before giving them any more cash.

Below are screenshots from CarScanner. The ambient air temperature was around 50 F. My LTFT appears to be acceptable at idle, but when I accelerate it shoots up to ~40%. This is making me think that it's a fuel pump issue? Another thing I noticed today was while accelerating into 2000+ RPMs, there was a soft clicking noise coming from the engine compartment. No idea if that's significant. If anyone knowledgable can weigh in, I'd much appreciate it because this has been driving me nuts.

 

Since you have a graphing scan tool I would do a VE test to get an idea if the MAF is reporting correctly.

What you do is a WOT pull though 1st gear, record peak RPM, MAF at peak RPM, and IAT, put that, your engine info, and the current barometric pressure in the calculator below.

If that checks out next step is checking fuel pressure.

https://atgtraining.com/atg-volumetric-efficiency-calculator/

 

Did the VE test this morning. According to the chart, a VE <55% = MAF fault? What would you recommend I do? Replace the MAF? Would it be safe to just keep driving? The truck's so old at this point, I wonder if this is something that even needs to be addressed. Or would I just be blowing more cash for the sake of not having a CEL on my dash. Oddly enough, the CEL turned off after flooring it. The CEL went away randomly once before during a road trip, but popped back up a few weeks later.

 

It looks like a skewed MAF sensor, I would verify the piping between the MAF and the thottle body is installed properly and has no holes or cracks as well as making sure the air filter is clean and installed properly before replacing the MAF.

Also are you running a stock airbox and air intake tube? Aftermarket air boxes, piping, and cold air intakes can greatly skew MAF readings because the sensors are calibrated for the airflow characteristics of the stock box and piping.

Be aware aftermarket and reman sensors can be hit or miss on quality and accuracy.

I would reccomend addressing it as running an engine too lean can cause engine damage.

 

I did a deckplate mod on the airbox years ago, but everything else is stock.

 

Not sure what that is but I would for sure inspect all the piping between the airbox and throttle body and pull the sensor just for grins and see if the other shop actually cleaned it, if everything checks out I would have to call a faulty MAF.