(P0171 and P0174) I have been monitoring and trying to fix this problem for a while now. Below i have everything i have done attempting to fix it.
-New MAF Sensor
-New PCV/Valve Cover
-New Intake Manifold Gaskets
-New Injector O-rings (Top and Bottom)
-Checked every hose i could find (Not replaced and im sure i missed a couple)
-Cleaned throttle body
-Cleaned PCV oil from intake and intake manifold
Things to mention:
-When i had the intake out i looked at the valves and they were literally spotless i have a picture and the runners had just a thin layer of carbon.
-Previous owner was or took it to an incompetent mechanic who left bolts loose around the transmission, im not sure if the engine was touched but i havent seen a missing bolt so far and every bolt i have taken off especially the intake manifold has been torqued to spec.
-Slight knock in the engine was diagnosed by my local mechanic to be a rod bearing but i havent replaced it yet.
-Im not sure how long it has been running like this but i have had it for around 5 months now and its been running lean since before i bought it.
-Drivers side Exhaust Manifold is leaking slightly.
I cant figure out how to post screenshots so ill just type out the the data i have from my OBDII scanner. (It is just a cheap bluetooth scanner so im not sure how reliable this info is plus im also estimating some of the values.)
Engine RPM: ~600 rpm - Idle
Oil Pressure: 26 psi
Fuel Pressure: 43.1 psi
MAF: 4.8 g/s
Intake Pressure: 4.2 psi
Fuel Trim B1-S1: -5.5%
Fuel Trim B2-S1: -3.1%
Long Term FT B1: 25.8%
Long Term FT B2: 18.8%
Obviously these are just static numbers so its kind of hard to guage what is going on but if for some reason its helpful and want the data of it sitting at 1500, 2000, and 2500 rpm then just tell me i even have screenshots if its possible to share them on here. Another thing to note is the first O2 sensor for both banks do show good readings going up and down like a heart beat but sensor 2 for both banks shows both sides as extremely lean. The fuel pressure at 43 im still not sure if thats normal, some places say 43 and other places say 55 im really not sure but it does slightly increase as you increase the throttle. If you need any more data please tell me.
For posting images, you can upload them to a image sharing site (such as postimages.org or also Imgur) and post the image links in your question.
Can you post the freeze frame data that goes with the codes? For what that means see here: https://www.samarins.com/diagnose/freeze-frame.html
Check for vacuum leaks. You could also try a fuel injector cleaning.
Good catch on vacuum leak.
I have checked for vacuum leaks absolutel every where and even went as far as replacing the intake manifold gaskets. Also already cleaned the injectors however i have to not im not a professional.
how did you check? The MAF reading is too low.
Smoke test. And what would the correct reading at idle be?
I would expect at least 6g/s
When i take the air filter off it goes up to 7 so im going to replace that but either way it still didnt fix the lean codes. What has me really stumped is bank 2 runs slightly richer than bank 1. Meaning if there is a leak on the intake would it most likely be on the drivers side as thats the side being affected more?
the code might not go away right away after making a change. It could take a few driving cycles to clear, or a reset command from your OBD tool.
Clarification: was the MAF sensor replaced with an OEM one?
Yes it was.
I do get 58 psi when starting cold and from whay i have read its normal for it to go down to 43 at idle. And as i mentioned the psi does increase when accelerating so as the pressure increases the injectors still arent pushing more fuel, the 2nd o2 sensor for both banks just show a flat line but when accelerating it shows it just barely getting any richer to accelerate.
So your oxygen sensors might be faulty.