01 Tacoma Stalling

2001 Tacoma V6 4X4:

So I recently had a Mech I trust replace all Qty (4) O2 sensors common to the Cad Converters due to a Check Eng Light for an emissions test. He made sure to redo the grounds too. After the work, my truck started turning off in the natural or in gear position with clutch in or out while decelerating above 30 MPH and/or 3rd gear or higher.

A Week later the Check Eng Light has returned with Codes P0171 (Bank 1 system too lean) & P0120 (Throttle/Position Sensor A Circuit) was generated.

So I replaced the Throttle Position sensor (TPS) since it was the easiest, cheapest and most logical chose.

Still have no joy with the situation since the TPS replacement did not fix the stall the discrepancy. Note both P0171 & P0120 still remain after TPS replacement.

Need Help with ideas. Think the computer might need to be replaced

 

I had a lingering P0171 code that wouldn't go away, turns out it was a vacuum leak. According to the mechanic I was working with, that's the most common reason for that code. Check all your lines and make sure they are secure and/or not cracked. Mine ended up being an uncapped port on the back of my supercharger, but since you don't have one (I'm assuming) then it could be a leak elsewhere. A leak in your exhaust could also throw that code.

Another common reason for a P0171 is a dirty/bad MAF sensor, also possibly a bad o2 sensor. You said you had them replaced but if nothing else works, it may be that one of them is bad or wasn't put in correctly? Or if you used aftermarket ones that might be the issue.

Cleaning the MAF sensor is super easy, that's where I'd start. Make sure you use MAF cleaner only, not electrical cleaner or carb cleaner.

 

Doesn't matter what make forum you go to it's always the MAF! Lol! In my 10 years of wrenching I have NEVER had a MAF be the fault unless the vehicle sucked up water and locked the engine.

 

I am curious just How you have (4) sensors since mine all have only 2

Upstream and Down stream

Funny I had a MAF sensor that just wore out at about 175,000 miles replaced with new one From Toyota fixed the issue.

 

Did you calibrate and span your throttle position sensor after installation?