Hello, I've been trying to figure out why my truck engine is lean bank1? It definitely is lean because of rpms jump a little while idle and engine performance=dog ****. The other code suggest evap leak(gross leakage). My truck is 2002 ford ranger edge with automatic transmission, v6 3.0 4x2. I was thinking these two codes could be connected. I replaced gas cap to no avail. Lastly I have no experience with cars.

 

Welcome to the forum

Engine will Ping if running Lean, and smoke if running Rich

Lean code means computer's air/fuel calculations were Lean by more than 15% so computer was having to add more fuel than it calculated
So engine was/is never running Lean, well for maybe 2 seconds

Loss of power can certainly be associated with this trouble code, but probably not in the way you think

Always good to post definitions with codes, since no one has them all memorized, lol, and also, so we can see what you are looking at for definitions, there are many incorrect definitions out there
P0171 System too Lean (Bank 1)
P0455 Evaporative Emission Control System Leak Detected (gross leak)

So lean means extra air is coming in that the computer didn't know about, so its calculations were off
And the EVAP system uses engine vacuum to prevent gas fumes from escaping the gas tank

So you have a vacuum leak and a lean code...................................
I would track down that vacuum leak first, since it may be causing your lean code

Bank 1 on a Ford V6 is the passenger side of engine, Bank 2 is drivers side
And there is an O2 sensor for/on each bank of the V6 engine
The O2 sensor sees Oxygen in the exhaust, the level of oxygen in the exhaust tells the computer if the air/fuel mix that was just burned was Lean or Rich
Lean is too much oxygen
Rich is to little oxygen
O2 sensors need to be above 600degF to work so they are not use on cold start, takes about 3-5minutes for them to get hot enough for computer to get Feedback on the air/fuel mix
So if an engine runs better cold but then starts to run poorly after a few minutes you can be pretty sure there is a problem with computers info, that is throwing off the calculations
It doesn't have to a be a sensor issue, air leaks, low fuel pressure, timing, spark plugs, these can cause poor running
But it can also be a sensor, the old computer saying, "garbage in garbage out" applies, if computer is getting bad data in then it will have bad data going out

O2 sensors are the only sensors that can "wear out", most sensors last the life of the vehicle, but O2s use a chemical reaction to detect Oxygen so they simply run out of that chemical after 125k Miles or so, and need to be replaced
And they will cause Lean codes to be set as they run low on the chemicals, and its a false lean so engine is actually running a bit Rich because computer is adding more fuel than needed, which causes poor running

So whats the age of your O2 sensors?
How many miles on them?

 

I have no idea the age of the o2 sensors. I just bought this truck from somebody. Idk the miles either but the truck itself has 200000 miles on it. So i have a vacuum leak? But that doesnt have to do with my lean code? Thats just my evap code?

 

I would change Both upstream O2 sensors, just on speculation, better MPG if they are original in any case, but without knowing the age it may just be a false Lean code that can have you chasing your tail looking for a problem that's just normal wear and tear

A Vacuum leak means air is being sucked in to the engine and the computer doesn't know about it, so its not included in its calculations, so when fuel is burned O2 shows lean, so computer compensates and sets Lean code to notify driver of the error in its calculations
If this is caused by a failing O2 sensor then only fix is to replace the O2 sensor, so best to do that FIRST

And since there are TWO upstream O2 sensors and only ONE is showing Lean its more "likely" its a O2 issue, because an air leak would tend to show up on BOTH Banks of the engine
It could be a lower intake air leak, or an exhaust manifold leak on that bank, but with questionable O2 sensors its best to just replace them since they DO wear out, and then go from there
Its not a waste of money since O2s pay for themselves in best MPG over the next 125k miles


EVAP system test
get a damp rag/towel and a short hose, like 3 feet, longer is fine but not too long, lol
Take gas cap off the filler hose
Put short hose in filler opening and seal it in place with damp towel, so it holds in air pressure

Now blow into the hose, don't use an air compressor for this, it will blow off fittings
Lungs can generate about 2psi, so won't blow off fittings

The gas tank should hold pressure, if not listen for air escaping
It can be helpful to have someone else blow while you listen, check engine bay as well for air escaping, thats where the vacuum comes from for the EVAP system

The filler tube often drys out and cracks or vent hose, this can cause P0455
Easy to hear air escaping from those hoses

 

So should I try and clear the P0171 code first and see if the engine is still lean? Or just replace o2 sensors?

 

Also how much of the hose should be sticking out? Do i put it all the way down the tank? or just open the little hole up and then stop?

 

Just a little bit of hose in the tank and seal around it with the rag, like a gas cap seals the tank

Engine is NOT running Lean
It would ping like crazy if it was running a lean mix

But yes I would replace both upstream O2 sensors, then clear the codes and see how long before it comes back if it does

There is a 3rd O2 sensor after that Cat converters, you can replace it if you want but don't really need to unless it sets its own code, it sees lower oxygen content exhaust so doesn't use up chemicals as fast, these usually last 250-300k miles

 

I found the vacuum leak with that cigar method. The smoke came out of where i colored with black marker. What is that thing? Also is that have to do with evap leak or is that seperate?

 

That's the IAC Valves vent cap, it just pulls off but shouldn't leak much air
Seal in the IAC Valve may be leaking

The IAC(idle air control) valve is how the computer sets the idle RPMs of the engine
It lets in more and less air by-passing the throttle plate to set RPMs when throttle plate is closed
A "controlled" vacuum leak

Because its a solenoid and a sliding valve there needs to be a Vent behind the slider so valve can move out and then back in without pressure building up behind it
Thats what that black cap is covering, the Vent
But it should be sealed not part of the air passage that the IAC Valve controls

You can only replace Ford IAC Valve with a Motorcraft or Hitachi brand IAC Valve, other brands don't work well with the Ford system(electrics)

But a leak there should effect BOTH sides of a V6 engine, so I doubt its your problem, but could be

 

damn so that was most likely a coincidence? i'm pissed

 

I just checked codes again now it says both banks lean? could it be the IAC valve now?

 

Yes, or the EVAP system leak

I would put O2s on hold for now, but still plan on changing them if you don't know the miles

Warm up engine and let it idle
Pull off the black cap on the IAC valve
Put finger over the exposed port, see if it effects RPMs, if not then its not the issue

Pictures of IAC Valve here: https://www.explorerforum.com/forums...-w-pics.84220/
Cap is just snapped on and off

 

Yea I pulled the cap off put my finger over it and nothing happened to the rpm. But when i took the vacuum hose connected to it and blew smoke in smoke came out of that I av valve. So I'm stuck

 

If it doesn't change RPMs then its not leaking enough air to cause Lean code
Try other vacuum hoses with engine idling, pull hose off the hose at its intake port and plug the port with finger, if RPMs drop follow that hose to the device using it

Vacuum is not "used up" on most devices, its just a pressure difference uses to move valves, exception is Power brakes and EVAP system

 

I saw online that checking short term fuel trim and long term could help figure out a vacuum leak. Short term percentage for both banks are -1% to 2%
Long term both banks sit at 30% is this normal? When I rev the engine up to 2000 rpm the long term drops by like half. I believe that indicates a vacuum leak.

 

Short term(STFT) looks good, -5 to +5 is normal

Long term(LTFT) is why the Lean codes, anything over 15-20 will trigger a code

Yes, could be vacuum leak, but......................could also be
Dirty MAF sensor
Clogging fuel filter
Low fuel pressure
Exhaust leak
Clogged exhaust

 

Ok. A mechanic told me he would charge 75$ to hook up a smoke machine to my truck is that worth it? Could you tell me how to look those things? I dont know how comfortable I am un plugging vacuum hoses because I really dont know which ones are vacuum hoses. I could also check the fuel pressue with my scanner as well in a little bit

 

There is no fuel pressure sensor, you can only test it with a mechanical gauge hooked to the test port on the engine

$75 would take that possible issue off the table, but I thought you already did that yourself?

 

I only tested the hose connected to the IAC valve but did your test and did not find the rpms going up. I wanna check the fuel filter but i think i might have to take the whole gas tank out. I'm not sure where its located. The manual says my filter is a FG-1002

 

Fuel filter is in the frame rail under drivers seat area, easy to get to, you need a special tool to remove the fuel lines

I would get/rent a fuel pressure gauge first, the kits run $35, like this one:
Most auto parts stores rent or loan them for a few dollars

2002 Ranger should have 55psi at idle and then raise RPMs to about 2,000 and hold it there, it should hold steady, if its slowly dropping then you have a delivery issue, filter change first, if its still dropping then fuel pump is the next stop

Also get a vacuum gauge, they run $20, engine should show 18-21" of vacuum at idle
Run it up to 2,000rpms again and it should drop and come back to what it was before with steady rpms, if its slowly dropping then exhaust is partially blocked
You can also "blip the throttle", open it quickly and let it snap closed, vacuum should drop quiclky then pop back up to what it was before, if its slow to return then blocked exhaust

 

****

 

You know that what you are seeing is the EVAP system pressure inside the gas tank(i.e. FUEL TANK pressure), and NOT fuel pressure at the engine, there is no fuel pressure sensor

And EVAP pressure looks fine

 

oh... Well off to the store i go to get a fuel pressure gauge, If its to low then im fucked? because thats an expensive fix?

 

Well pick up a fuel filter while you are there($15-$20), make sure it comes with the "tool" to remove the fuel lines

Then if it is low you can change the filter and retest

 

They didnt have the fuel filter i needed, but i got the pressure gauge. Is this where i put it?