P0171 P141 Error codes PLEASE HELP!!!

Hello Tacoma World! This is my first time ever posting a thread, as I am out of ideas on how to go about fixing this issue. So here it goes…

Recently, my truck began to sputter and bog on the throttle, before i received the dreadful "check engine" light. having this issue before i figured that it was likely the MAF. I do have a K&N air filter, and yes, i have cleaned it myself and encountered the issue of oil residue on the MAF before; However, in this case a dirty MAF sensor is unfortunately is not the issue. Long story short, i have replaced the MAF sensor with a "brand new" sensor from Autozone, meaning i got the one with the lifetime warrantee; and i have had the ECU re-flashed, cleared etc. Thinking i was in the clear, after driving for about 10 miles, my check engine light came back on again!…

So i pull the codes again, and now I'm only getting codes P0171 and P0141 for both the left and right bank too lean; whereas before i was getting the MAF sensor id'd as part of the problem. So now I'm thinking there has to be a vacuum leak somewhere since I've replaced the MAF sensor already and, i know it can't be the O2 sensors since I'm not getting codes for them nor would i imagine both of them going bad at the same time.

In an effort to find the leak, I've sprayed carb cleaner all around the vacuum lines to see if i could find a l leak somewhere; and i got nothing.

I then decided it was best to just take it in to have it smoke tested to make for sure that I wasn't doing something wrong, and the results were also inconclusive. So now i am lost!…

I don't know if this helps provide a better understanding on what is going on but for some reason, after i replaced the MAF sensor, it runs perfectly fine till i break 50-60mph. At that point it seems to start idling rough from then on.

With that said, I have 103k miles, a new MAF, no vacuum leaks, and Im almost positive that my 02 sensors are good as well. If anything, i think my biggest fear is that my injector seals may be going bad; however, i find it hard to imagine that to be the issue as I'm sure i would be experiencing the sputtering issue throughout the entire power-band, rather than just above 50-60 mph. If anyone has some input on this issue, i would genuinely appreciate it!..

Respectfully

-Isaac

 

Hey E.M.T:

This is my first post, just took delivery on a 2014 DCSB with the off-road pkg. While no first hand issues with a Tacoma, I've chased these codes down several times on my highly modified Subaru STi, and a friend's Ford V6. So maybe I can help.

PO141 as you suggested is often caused from a vacuum leak. If you didn't already, spray carb cleaner around the intake manifold, Throttle body, EGR Valve and all the hose connections. The lean code means your sucking enough air past the MAF that to balance the A/F ratio your engine is requiring fuel beyond the limits the computer has set for the fuel trim levels. I've also seen the air seal around the MAF leak so don't forget to check there too.

The other way to check for a vacuum leak is to remove the plastic tube past the MAF. With the engine off you gently pressurize your intake system. I made a device that allows you to inject compressed air into the air intake pipe. The premise being if air can get sucked into the system from a given location it will also bleed air from that same location. If you have a leak you should be able to hear the air pressure hiss identifying the area of the leak. Look for any cracks in the plastic piping and all of the rubber hoses and plastic connectors.

Exhaust leaks can also cause improper readings like lean codes and rough idle. With the truck running, crawl underneath and put your hand around every pipe connection and feel for pressurized air leaks and listen for an exhaust leak. Check the threaded bung on the O2 sensor(s) for leaks, especially the one after the Cat. That is the Bank 2 sensor throwing a code. Look at the wires and connectors on that sensor to make sure nothing is damaged and check for good clean connection and proper installation.

If you know someone else with the same truck, borrow their #2 sensor (after the cat) and try it in your truck. Clear the codes and see if at least the P0171 code goes away. That would at least give you some indication if your O2 is good.

Wish I could be of more help. Don't give up, you'll find it.
Good Luck, Gary

 

First, we need to know what year truck, motor size, etc.. If you have a 1st gen, check your IAC valve. Remove it, clean it, and make sure the gasket is ok. Not too familiar with the 2nd gens.