2000 3.4 CEL input suggestions

[Ktundy]

Hi there,
I'm sure there is a search button I could utilize and find an answer that I may or may not have seen. I have a small problem.
CEL comes on, code reads P0171....Bank 1 lean. I have replaced all vacuum lines, cleaned the MAF 10 times, replaced 1 of the 02 sensors (passenger side), spark plugs/wires are new. I have a scanner and can clear the code. I will drive a short distance like in and around town and light comes back on, clear the code and hit the freeway drive 200 miles and no CEL, but stop get fuel and get out of town and CEL is back. Same codes. I have not replaced the MAF itself though, I'm still trying to be semi cheap because they are a bit spendy but does anyone have any other ideas?
Thank you very much
Kevin

 

[Buckaroo]

I think this is a two trip DTC which means that you need to drive it two times with key off in-between to set the CEL. So that may explain the difference in miles driven when the code is set. Check for pending codes on the first trip - it is likely there waiting for the second trip.

This is a list of potential causes from the Factory Service Manual for DCT P0171..System too Lean (Fuel Trim)


Air induction system

Injector blockage

Mass air flow meter

Engine coolant temp. sensor

Fuel pressure

Gas leakage on exhaust system

Open or short in heated oxygen sensor (Bank 1 sensor 1)
circuit

Heated oxygen sensor (bank 1 sensor 1)

ECM (at the end of every list - not a very likely cause)

This code has been associated with MAF issues on our truck but there are other things to consider per previous list. TheDurk posted the MAF cleaning procedure a while ago - make sure you are cleaning the MAF hot wire which is around the corner from the temperature sensing bulb which is visible when you look down the throat. You can also back probe the MAF with a voltmeter (DCV) to see if readings make sense. If you have a voltmeter and need help figuring that out - PM me.

Buckaroo

 

[Buckaroo]

Link to thread regarding MAF cleaning....

http://www.toyota-4runner.org/3rd-gen-t4rs/86675-help-p0171-3.html

 

[Ktundy]

Thank you guys for replying. I watched some more videos and did more research. Happy to report since sunday and plenty stop and go and freeway driving and NO CEL. There are two hidden little wire strands that are up in the top of the MAF and sure enough they were completely covered in $#@!. Cleaned them with alcohol and Q Tips.They are tiny and horizontal and all clean now. I hope this solves my issue. Power is up as well.
Kevin

 

[Ktundy]

Yes exactly what your link says to do! Thanks again.