I’m new to the forum and I’ve got a 2005 ranger edge 5 speed manual with the 3.0 v6. Currently have check engine light so I ran the code and came up with both banks running lean. It runs completely fine no misfire or lack of power (I think). I looked at the freeze frame of the engine stats when the code set and I was going 22MPH With 2500rpm. So I don’t think it’s a vacuum leak since that typically effects idle. I doubt it’s a fuel problem because I just recently had my old fuel pump and fuel filter replaced very recently. I guess it could maybe be the MAF sensor but I had that replaced sometime within the last year. Any ideas?

 

Pretty simple to test for vacuum leak
After engine is fully warmed up, let it idle and unplug the 2 wire connector on the IAC Valve, it will close
Engine RPMs should drop to 500 or so or engine may even stall, either is GOOD, no leak

If idle doesn't drop then there IS a leak or leaks


LEAN codes don't mean engine is actually running Lean, lean and rich codes mean the computers air:fuel calculation is off, in this case computer is having to add at least 15% more fuel to both banks of the engine to get the O2 sensor to show correct oxygen levels in the exhaust

2005 computer is programmed for 55psi fuel pressure, there is no fuel pressure sensor, new pump means fuel pressure SHOULD be checked, not "its OK", new does not mean what it use to mean, lol
Computer is also programmed for 3 LITER engine, and for the Stock size fuel injector, assuming these are the same

MAF sensor WEIGHS the incoming air, computer already knows how much air is coming in, at any RPM and throttle position(its a 3 liter engine so its just math), but it doesn't know the WEIGHT of that air, which varies by temp and elevation above sea level

How old are O2 sensors?
They last 125k miles then start running out of the chemical needed to read oxygen levels, so will cause Lean codes, but a real long shot for BOTH upstream O2s doing it at the same time

Could be blocked exhaust, you say it runs OK so long shot here as well, a partially block exhaust will cause rough running at higher speeds and also cause Lean codes

Best recommendation, is never ASSUME
Test for vacuum leak
Test fuel pressure, and hold engine at 2,500rpm for 30 seconds or so to make sure pressure is not slowly dropping under load

 

Yea I figured it wasn’t the o2s because they’d both have to go out at the same time for it to read both banks.

I guess I didn’t think about the fuel pump not working correctly since it was new but I still have the stock injectors.

I do remember pulling the wires off the IAC and I could tell it wasn’t running right. So I guess it’s not a vacuum leak.I ordered a better code reader so I can take a look at the fuel trim In the short and long term so I can trouble shoot a little better.

the strange thing is that I wouldn’t of known it was running lean until the cel came on so it must be just lean enough to set the code but not enough to cause it to act weird

i was looking at some live data tonight and my Intake air temp sensor was reading 114 degrees F when it was probably 80 outside and the engine was cold, I’m not familiar enough to know if that’s normal to be off that much or somethings wrong? I know if the computer thinks the air is warmer than it actually is it’ll cut back on fuel and maybe causing it to run lean?

 

When you disconnect IAC wires(engine WARM) you should notice a BIG difference, rpm DROP to 500 from say 750, or engine stalls
"I could tell it wasn’t running right" isn't one of the outcomes of unplugging the IAC Valve, IAC doesn't effect fuel or spark, just RPM
So try it again

As said, the engine was never EVER running Lean, that is not what the code means, its a computer calculation error, and computer is letting driver know, "lean" in this case means computers calculation is "lean" not the actual engine

If your engine ever ran lean it would ping/knock like crazy and over heat, just like if it ever ran Rich it would blow grey/black smoke out the tail pipe

Yes, check IAT(intake air temp) sensor again, after engine is warmed up and running, if its high again then replace it, its not an expensive sensor and can cause Lean code if its showing too high a temp over actual temp

 

Sorry to be vague I meant that I could hear the engines rpm drop I didn’t exactly look at the rpm but I could tell it was struggling for air. I’ll warm it up tomorrow and see what rpm it drops to specifically. and I’ll see what the air temp is

 

As long as RPMs drop that would be good enough

 

Just warmed it up all the way and with the IAC plugged in it idled from 700-750 when I unplugged it it didn’t seem that affected it ranged from about 650-700. No where near stalling, im not sure how dramatic it’s suppose to be but maybe a minor vacuum leak?

I checked on the Intake air temp and it didn’t really go below 110 degrees F. I realize these sensors aren’t accurate to a degree but is that unusual? I just checked the weather and it says 88 degrees F. Do you know if the temp sens is in the MAF or somewhere else on the intake. Havnt been able to find it anywhere else so I assume it’s in the MAF.

 

IAT sensor location changed by year and engine model

Look at the MAF sensor, if it has 4 wires IAT is separate and on the intake manifold, if it has 6 wires then IAT is in with the MAF sensor, so you have to swap both/whole unit

They are pretty accurate, so that's reading too hot with engine running, must be looked at with engine running

 

Got my new scanner today and warmed her up and I found two things that are very odd. With the engine idling warmed up ac off the long term fuel trim in both banks is about 10-11. As soon as I turn the ac on both banks immediately stay at 25. Is it just because of the load? If so wouldn’t the values level off to 10-11 like if you were to raise the rpm?

another thing, I noticed that the long term fuel trim on both banks on sensor two is reading 99. I’m not sure where it’s getting this data from or what it means. I thought there’s only one o2 sensor on each bank and then one after the cat?

i also noticed that at idle the engine load is about 42% is that normal? Seems like it should be in teens or twenties.

 

1995 and up Ranger had the newer computers so got O2 Sensor "2s"

O2 sensor "2s" are after the Cat converters
O2s after the Cats are called downstream and should show Low Oxygen, so .7-.8volts and steady

On a "V" engine there are usually 3 O2s
Bank 1 sensor 1
Bank 2 sensor 1
Bank 1 sensor 2<< single exhaust behind Cats
Bank 2 sensor 2<<dual exhaust behind Cats

Fuel trims(STFT) at idle will be high, to prevent engine from over heating, computer ignores O2 sensors at idle, same as it does at WOT(wide open throttle)
So ignore idle STFT

STFT are NOT how the engine is running, its how the computer's calculations are running

The computer constantly calculates 0 STFT, its then burned and O2 sensor "1s" tell computer if exhaust had too much oxygen(Lean) or too little oxygen(Rich)
The computer then adds more fuel, +5% STFT or less fuel -5% STFT to its initial calculation and burns that

Codes are set if computer calculations are off by more than 15-20% either way, long term, this would indicate a problem with the numbers used in the calculation, and maybe even in the computer, although that's a long shot
Usually there is a problem with a "number" the computer is using, i.e. air weight, so vacuum leak, MAF issue or Air temp issue

Long term fuel trims(LTFT) are used so computer doesn't have to redo calculations as engine/vehicle gets older
Older vehicle will have small air leaks, a little lower fuel pressure, lower compression, dirty injectors, ect......................
So LTFT is used after computer does its base calculation
So if LTFT is +8 then computer set 0 STFT as 0 + 8 and that's the new 0 STFT, so if your STFT while driving is +5 and LTFT is +8 then actual fuel trim is +13
And if its stays at +5 then LTFT will change to +9 or +10 over time

If you had a vacuum leak and fixed it, then STFT would show -5 for awhile and LTFT would start to come down from +8 over time
-8 to +8 is normal STFT operating range

Engine load is calculated by air flow so not like the "load" of driving or hauling something, 40%-50% is normal with AC on
In this case its MAF sensor grams/second to engine's theoretical maximum grams/second so you could be driving at 70MPH with AC on and be at 30% load, well maybe going a little downhill, lol

 

I pulled the PCV Hose on the driver side bank(not sure if that side is 1 or 2) that connects to the intake manifold and oil started pouring out so I figured my valve was broken and left open and was letting excess air in that wasn’t passing through the maf sensor.

Needs an oil change anyways autozone didn’t have the right part so I’m going to ford dealership tomorrow to get the part and I’ll do an oil change and replace the valve and see if that fixes it.

 

So I just wanted to update this post since the PCV valve wasn't the whole problem. The PCV valve still needed to be replaced as it was letting a lot of oil get by and i'm glad i found it but it didn't solve my vacuum leak. My engine never actually sputtered or ran poorly it just kept coming up with CEL on my dash that was driving me crazy and my fuel trims were always a lot higher than they should be. I ended up taking it to a shop that did a smoke test and it turns out the leak was coming from the throttle body assembly which means the seals on the butterfly valve shaft and letting air in. This explains why no matter how many vacuum ports i closed off my fuel trims always stayed high.

The reason i wanted to update this is I cant really find anywhere on the internet where another ranger has had this problem. I looked for replacement throttle bodies for my truck and cannot find one for less than $600 because they don't make them anymore. I sent it to rock auto for them to rebuild it and it was a complete waste of time. I had to pay to ship it both ways just for rockauto to hold on to it for two weeks and tell me that they could not rebuild it.

So now i am back at square one, i'm probably just going to see if i can try to push the seal in a little bit when it arrives back from rock auto and see if my fuel trims go back to normal. If not I will probably end up getting a junk yard throttle body since that seems to be my only option because i cannot stomach to put a $600 throttle body on a 15 year old truck with over 100k miles.

Anyways I appreciate all your help RonD !!

 

If everything else about the truck is good, I'd have no problem spending $600 on it.

The 3.0 is a decent engine, should be able to double your miles.