P0174 Bank 2 system too lean P0305 cylinder 5 miss

P0174 is bank 2 lean.
To differentiate between bank 1 and bank 2, bank 1 has the number 1 cylinder in the firing order, the other bank is bank 2.
I looked at v6 2.5L engine, bank 2 should be the front bank, looking at the engine under the hood.
Are there any driveability issues? Everything off, unplug your maf sensor, where applicable, take it for a spin, if it does better have to check maf system.
If lean fuel trim code set under load, almost always, fuel pressure or volumn.

Definition of Diagnostic Trouble Code P0305 Category: Powertrain Definition: Cylinder 5 Misfire DetectedNote: This definition of P0305 is applied to all manufacturers

Definition of Diagnostic Trouble Code P0174 Category: Powertrain Definition: System Too Lean Bank 2Note: This definition of P0174 is applied to all manufacturers

P0305 is a # 5 cylinder misfire , do you know what that is ? Check engine light flashing indicates a severe misfire that can damage the catalytic converter . Don't drive this vehicle ,take it immediately to a qualified repair shop or the dealer .
A Ford P0171 is a LEAN code for cylinder bank 1, and P0174 is a LEAN code for cylinder bank 2. These codes commonly occur on many Ford vehicles, and are set when the powertrain control module (PCM) sees the air/fuel mixture is running too lean (too much air, not enough fuel).

Flashing check engine light CarMD

P0171 System Too Lean (Bank 1)
P0174 System Too Lean (Bank 2)
P0301 Cylinder #1 Misfire Detected
P0302 Cylinder #2 Misfire Detected
P0304 Cylinder #4 Misfire Detected
P0306 Cylinder #6 Misfire Detected

Intake or vacum leak will be the first codes 174,171, try idle and spray propane around intake if car idles up, then intake is leaking, otherwise could be a broken vacum line, check with a gauge

OK, We'll cover the Diagnostic Test Codes (DTCs), starting with the standard definition set by SAE J2012 (Revised December 2007)
DTC P0171 "System Too Lean Bank 1"
DTC P0174 "System Too Lean Bank 2"
DTC P0301 "Cylinder 1 Misfire Detected"
DTC P0305 "Cylinder 5 Misfire Detected"
DTC P0316 "Engine Misfire Detected on Startup (First 1000 Revolutions)"

The "system lean" codes are pretty much telling you that there is way too much oxygen in the exhaust. There is too much oxygen on BOTH sides of the engine, and that is why you are getting codes for bank 1 and for bank 2. Bank 1 is the side where #1 cykinder is located and Bank 2 is the opposite side.

The misfire codes are pretty self-explanatory. #1 and # 5 cylinders are misfiring. The P0316 DTC is telling you that the misfire monitor is detecting a misfire as soon as the engine starts. This tells you that it is a very severe misfire and that the engine does not have to warm up and the car does not have to be driven to detect the misfire.

A misfire can be caused by many things it can be vacuum leaks, bad spark plugs, bad ignition cables, faulty ignition coils, fouled or malfunctioning injectors or injector circuits, blown head gasket, cracked cylinder head, burnt valves, etc.. etc..

However, look at the codes you have. Then look at the firing order for your engine. 2002 Mercury Sable is only equipped with a 3.0L 2V 6-cylinder engine.
The firing order is 1-4-2-5-3-6

Now if you take the firing order and split it in half, stack the two halves on top of each other, it looks like this:
1-4-2
5-3-6

When you look at the firing order this way, you can see that cylinders 1 an 5, 4 and 3, and 2 and 6, are "PAIRED" cylinders. They are exacly opposite in the firing order. Now, the cylinder only fires every second revolution of the crankshaft. With paired cylinders, one of the cylinders in the pair will fire on the first revolution and the other cylinder will fire on the second revolution.

Looking back at your codes, please note that the cylinders that are setting the misfire codes are paired cylinders.

Now the coil pack for your ignition is actually made up of three coils. Each coil fires a set of paired cylinders. If you look at the top of the coil, it will usually be marked with the cylinder numbers that each coil tower is supposed to connect to. The coil will look just like the firing order split and stacked as above.

With all of this said, I would say that it is VERY LIKELY that your misfire codes are being caused by a defective ignition coil.

The lean codes are a little different.

These are USUALLY caused by vacuum leaks which allow too much air into the engine that is not getting measured by the Mass Airflow (MAF) sensor and causes the engine to be getting too much air and not enough fuel (running lean).

I would take a good look at all of the vacuum hoses and lines. Ford is notorious for getting holes in the rubber parts that connect the PCV tubes.

If you do not find any obvious reasons for a vacuum leak, then you may want to fix the misfire codes, reset the computer memory, and drive the vehicle to see if the lean codes come back again. The misfires COULD be the cause of the lean codes. In a perfect world, this is not supposed to happen because the misfire monitors setting codes will not allow the oxygen sensor monitors to run and set lean codes. However, I HAVE seen cylinder misfires that have caused lean codes.

I hope this helps you to figure it out. Good luck!

P0171 System Too Lean Bank 1
P0172 System Too Rich Bank 1
P0173 Fuel Trim Bank 2
P0174 System Too Lean Bank 2

OK, that's a partial list of codes, the fuel delivery is controlled by the oxygen sensors, so it's possible that something in that area could be causing your problem.

However, it could also be clogged fuel injectors that can't deliver enough fuel to the cylinders compared to the air that is pulled into the engine.

Try some fuel injector cleaner for that poured into the gas tank.

How does it run?
Does it miss at all?

p1151 indicates fuel system lean bank 2, p0174 system lean bank 2, p0305 is missfire cylinder number 5. You say no power I take that to mean that is has low power while running, if so with these codes present check your fuel pressure and pressure regulator and fuel pump, it sounds like your fuel system has low pressure and is not responding correctly. Hope this helps, let me know.

P0171------ system too lean bank#1
Po174------ system too lean bank#2
For these 2 codes, try cleaning the maf sensor (mass air flow), that is mounted in the big black hose that goes from the air filter housing to the throttle plate, if it is dirty, that will cause those 02 sensors to send a signal to the computor to lean the air fuel mixture. If cleaning it doesn't work, the sensors will probably need changing.
P0300---- Random/multiple cylinder misfire
P0316---- Cylinder misfire at start up---- first 100 revolutions.
On those 2 codes, you have to do some testing to find out why there is a misfire.
Possible causes:
dirty/malfunctioning injectors
weak coil pack
fowling spark plugs/wires
Low fuel pressure

i had asimiliar misfire on my 2000 windstar.the first thing to check is a broken valve spring by taking off the valve cover the other is a o2 sensor bank 2 i believe is the downstream.if not the valve spring then either the coil pack or thecontrol module. either way it is fairly inexspensive