Taco tick with p0171 and p0174

Hey everyone! I'm a proud new owner of a 2nd gen 05 dbl cab and I love it. I work with my hands, but am not too savvy when it comes to engines and bought this truck with the intention of learning some things. Shortly after buying, the check engine light came on. Then the muffler broke and so I replaced that. I went and bought a scanner to check the problem with the engine light and got the p0171 and p0174 codes telling me that bank 1 and 2 are running lean. So I came on here and looked around thinking I had a vacuum leak somewhere so I did the propane trick and had no results. I also very much notice the smell of exhaust after turning it off and what I've come to know as the "taco tick". I really believe all of these things are related. After failing with the propane test, I really hear the ticking coming from the driver side and when I touch the vacuum switching valve, I can feel the tick as well. Is it possible that this is all caused by the switching valve? Or possibly a gasket in the manifold? I was really hoping the propane test would find something, but I looked all over and it never revved which leads me to believe it's deeper in the engine than just a hose somewhere. Thank you to anyone that replies and I'm looking forward to being part of the team here

 

Propane will only drive the A/F sensor rich.
Going off the engine reving is not how you preform that test.

You need to monitor the A/F sensors when doing that test.
The propane should drive the sensor and fuel trims rich.

Graphing the data helps.

Those codes are for both banks.

I'd want to see ECT, MAF, and Sensor voltages.
Than test drive it and see if the trims come down. (graph data)

Other than that, you need to physically test suff.

 

Hey thanks for the reply and I apologize in advance for being a complete noob here. I watched several youtube videos suggesting that the propane would rev the engine which is why I thought that. Since I'm not getting a rev, you're suggesting to monitor the airflow sensors while performing the test? What are the ETC, MAF and sensor votages supposed to be? My idle is around 700rpm which I'm also not sure of. And forgive my ignorance, but what are trims?

 

ECT should ambient temp on a cold temp (outside air temp)
And around 190-195 on a warm engine.

MAF should be less than .7 g/s with engine off.
Engine running hot idle it should be 3.5-4.5 g/s

 

Ok so I have engine off readings of
ETC at ambient temp
MAF .078 lb/min

On I have

ETC 190
MAF .468 lb/min

The only o2 sensors I have show
02 b3s2 .155-.680 and the same for 02b3s2

The rest of the sensors say n/a

 

Also I just want to say that I love that you put your name as Deogee. I was travelin' when I met her

 

MAF data looks good at idel.
I doubt it's bad at higher rpm.

But you can check -
At 2,500 RPM - Between 13.1 g/s and 18.9 g/s (shift position: N, A/C: OFF).