Help with diagnosing lean bank 2

[Kyleag89]

My 07 GT has been setting a P0174 code which is lean bank 2 since I purchased the car about 2 months ago. I am looking for a little help with diagnosing what is causing the code to set. It only comes on every once in awhile and usually when accelerating hard which seems like a fuel delivery issue to me. So far I have inspected for vacuum leaks and found none(could still be a leak but very small and hard to find). I also replaced the fuel filter since the car has 93k miles and I didn't know if or when it was last replaced. I have a simple OBD2 scanner and have looked at the PIDs but I am not sure exactly what some things should read. My fuel trims are around 8% at idle and steadily increase to around 16-20% at 2500rpm. So that data is what lead me to think its a fuel delivery issue rather than a vacuum leak, is that correct? The scanner also says my fuel rail pressure is 39psi at idle and I have seen it vary from 38-41psi under various rpms which seems to indicate the pump is ok but I'm not sure. I can hear a weird noise when turning the key on engine off and priming the fuel rail but cannot pinpoint it. Sometimes it sounds like the pump itself making the noise and sometimes it sounds like it may be from somewhere else.

 

[Dino Dino Bambino]

Your engine could have clogged injectors. Try running a bottle of fuel system cleaner (STP or Wynns will do fine) in your next tank of gas and see if things improve. I do this routinely once/year to keep the fuel system in tip top condition.

 

[Kyleag89]

Your engine could have clogged injectors. Try running a bottle of fuel system cleaner (STP or Wynns will do fine) in your next tank of gas and see if things improve. I do this routinely once/year to keep the fuel system in tip top condition.

I put an entire bottle of Redline fuel system cleaner in last night then filled the tank. I read that redline has the highest concentration of PEA and is very good at cleaning injectors. If nothing changes I guess I will start reading up on injectors. I can swap them out no problem but is there a way to tell if they are clogged before buying new ones?

 

[Dino Dino Bambino]

is there a way to tell if they are clogged before buying new ones?

Not really. You'd have to remove all eight and take them to a shop that can measure the injector flow rate. An ultrasonic cleaning might be enough to restore their health but if you need new ones, a set of stock replacement Ford Performance LU24 injectors would be fine if your engine is N/A, putting out less than 360rwhp, and running on pump gasoline (not E85).

 

[Macman45]

Dino is probably right but I'm just sharing my experience: does the car have a CAI?
My last S197 had a P0174 lean bank 2 code when I bought it, and I first ignored MAF, CAI, etc basically anything that I thought would trigger BOTH banks. Turns out the tune for the CAI was somehow wiped out. I flashed it with HPTuners for the CAI's opening and it's been perfect ever since.

 

[StockishS197]

If the car isn’t stock, it most likely has a tune that needs to be adjusted. The fuel trims being off by ~20% is what is setting your code.

You could also check the fuel filter to see if it is clogged

 

[Kyleag89]

I replaced the fuel filter and thought that would be it because it was nasty and the new filter seemed to allow more air through when blowing through it but hasn't changed. My car does have a BBK cold air intake with a very large cone filter. It also has a functioning Shelby style hood with the air intakes dumping right into the CAI. That was my first suspicion because the engine light will only illuminate when I am WOT.

 

[Kyleag89]

Here's a pic of my hood. Is there any way to tell if the car has a tune or not? According to American muscles website the BBK intake does not require a tune but my car may have a tune and that is causing issues? I am stumped at this point and will continue driving it and see if the issue gets worse.

 

[Dino Dino Bambino]

Here's a pic of my hood. Is there any way to tell if the car has a tune or not? According to American muscles website the BBK intake does not require a tune but my car may have a tune and that is causing issues? I am stumped at this point and will continue driving it and see if the issue gets worse.
View attachment 114017

There's no way to tell just from looking at the car whether it has a tune but I can say that:

1. Your hood looks mean but those "ram air" ducts are purely cosmetic, aren't even in the right place, and are of no functional use whatsoever.

2. It's more likely that you have the BBK CAI combined with the stock tune, and that could be what's causing the engine to run lean at WOT. I suggest you reinstall the stock air intake assembly if you still have it and see if that resolves the problem. The BBK intake is crap anyway.

3. In future if you're ever going to buy a CAI, get the JLT series 3 with a Brenspeed 91 octane tune. You'd love the extra performance, sharper throttle response, and the induction sound is so addictive!

 

[flash_xx]

I'd start with the easiest part, get a couple of new O2 sensors, they are cheap and with how old our cars are getting replacing them isn't a bad idea. Also, have the injectors cleaned by a shop. Not expensive and does wonders no additive could ever match, you can even find youtube videos of how to diy it if you're mechanically inclined. Clean the maf sensor, with (ONLY) MAF sensor cleaner. Fuel pump should be checked. It could be dying or have a clogged sock, filter definitely should be replaced. As a matter of fact, just replace all the fluids, from the coolant to the brakes and trans and diff as well as engine of course. I've had my 07 since new, and 19 years later we're still best buddies. The 3V is extremely reliable if you treat it well. Have fun!

One thing aout those "cold air intakes". They are anything but. Hot air is all you're getting out of them. As a baseline, get your stock intake back on and if you don't have it grab one off Ebay, if the car didn't come with a tuner or you have no idea if it's tuned, take it to dealership and have them reset it back to stock. Having a car with unlnown tune and/or mods is a money pit, better restart and build as you like it.

 

[Kyleag89]

There's no way to tell just from looking at the car whether it has a tune but I can say that:

1. Your hood looks mean but those "ram air" ducts are purely cosmetic, aren't even in the right place, and are of no functional use whatsoever.

2. It's more likely that you have the BBK CAI combined with the stock tune, and that could be what's causing the engine to run lean at WOT. I suggest you reinstall the stock air intake assembly if you still have it and see if that resolves the problem. The BBK intake is crap anyway.

3. In future if you're ever going to buy a CAI, get the JLT series 3 with a Brenspeed 91 octane tune. You'd love the extra performance, sharper throttle response, and the induction sound is so addictive!

The hood air intakes are 100% functional I will post a pic of underneath and you can see. There is an air channel inside the hood that runs over to the drivers side above the air intake. I didn't buy the BBK intake it came on the car when I bought it 2 months ago and the PO died in combat while serving in the Army.

 

[Kyleag89]

I'd start with the easiest part, get a couple of new O2 sensors, they are cheap and with how old our cars are getting replacing them isn't a bad idea. Also, have the injectors cleaned by a shop. Not expensive and does wonders no additive could ever match, you can even find youtube videos of how to diy it if you're mechanically inclined. Clean the maf sensor, with (ONLY) MAF sensor cleaner. Fuel pump should be checked. It could be dying or have a clogged sock, filter definitely should be replaced. As a matter of fact, just replace all the fluids, from the coolant to the brakes and trans and diff as well as engine of course. I've had my 07 since new, and 19 years later we're still best buddies. The 3V is extremely reliable if you treat it well. Have fun!

One thing aout those "cold air intakes". They are anything but. Hot air is all you're getting out of them. As a baseline, get your stock intake back on and if you don't have it grab one off Ebay, if the car didn't come with a tuner or you have no idea if it's tuned, take it to dealership and have them reset it back to stock. Having a car with unlnown tune and/or mods is a money pit, better restart and build as you like it.

Thanks for the info, I have found an intake leak that is very tiny all the way at the end of the intake closest to the firewall on both sides but slightly worse on the drivers side. I have already gone through most of the car and replaced fluids. I just flushed the entire brake system 3 days ago. The car has 6 piston brembo calipers in the front with massive rotors that I think are from a 2015+ mustang. The brake flex lines have been replaced with stainless steel braided hoses as well. I cleaned the MAF with maf sensor cleaner as well. According to my scan tool I am getting good readings from both 02 sensors as well as the MAF. Fuel rail pressure is usually 39psi but have seen it range from 36-42psi while driving.

 

[Kyleag89]

 

[Kyleag89]

Heres one with a work light shining through the scoop on the hood.

 

[Macman45]

That honestly doesn't matter. A Lean condition is unmetered air, which means are PAST the MAF sensor. I don't care how much air you give it before the sensor (hood scoop, ram air, NO hood, doesn't matter). You need to verify you have the correct fuel map corresponding to the CFM and diameter of the opening the MAF lives in. I still think you need a reflashed tune to the BBK

 

[Juice]

This is NOT an issue with something that is common to BOTH banks. (fuel pump, fuel filter, MAF, etc)
The code is telling you the engine has an issue on ONE bank. So the cause has to be one of those 4 cylinders, possibly an exhaust leak on that side.
Misfiring cylinder can show up as a "bank lean" and not set a misfire code if the number of misfires is below the threshold for tripping a P30x code.

Either look at mode6 data and see if any cylinders are loggin misfires. Might have a few single digit counts that do not increase, thats normal. Pulling spark plugs on that bank for a visual inspection may also be useful, if there is an issue, ONE plug will look slightly different. Might as well do a compression test while the plugs are out.

While a bad injector is a possiblity, it is a very low probability. Ive come across maybe 2 bad injectors in 50 years. I've seen injector inlet screens clogged with debris, but that is not a failed injector. Cleaned the crap out and those worked just fine. If you identify one cylinder that is logging misfires, you can swap it's injector with one that is not logging issues. If the issue moves, you found a bad injector. If the issue remains on the same cylinder, its not a fueling issue.

 

[Macman45]

This is NOT an issue with something that is common to BOTH banks. (fuel pump, fuel filter, MAF, etc)
The code is telling you the engine has an issue on ONE bank. So the cause has to be one of those 4 cylinders, possibly an exhaust leak on that side.
Misfiring cylinder can show up as a "bank lean" and not set a misfire code if the number of misfires is below the threshold for tripping a P30x code.

Either look at mode6 data and see if any cylinders are loggin misfires. Might have a few single digit counts that do not increase, thats normal. Pulling spark plugs on that bank for a visual inspection may also be useful, if there is an issue, ONE plug will look slightly different. Might as well do a compression test while the plugs are out.

While a bad injector is a possiblity, it is a very low probability. Ive come across maybe 2 bad injectors in 50 years. I've seen injector inlet screens clogged with debris, but that is not a failed injector. Cleaned the crap out and those worked just fine. If you identify one cylinder that is logging misfires, you can swap it's injector with one that is not logging issues. If the issue moves, you found a bad injector. If the issue remains on the same cylinder, its not a fueling issue.

Maybe, but read above where others (myself included) have had ONE bank lean code only and it was tune related. I also would have thought both banks should throw lean if it was common to both sides.

 

[JC SSP]

Not knowing the cars history... I am not going to assume anything. Is the electrical system charging correctly, are there any loose or corroded wires, do you hear any exhaust leaks (stethoscope works nicely), you mention rear intake leak, there might be additional leaks too...

I would pull the plugs and focus on the passengers side (Bank 2). Any plug that is darker (running rich) vs lighter (running leaner) should be investigated. Swap plugs, coils and injectors to the driver's side (Bank 1) see if it moves around... This doesn't cost anything but your time...

If everything's checks out, then a smoke test to see if you have any vacuum leaks... after that, well you might need to revert back to stock tune or contact Lito for a custom tune...

 

[Kyleag89]

Update:

The problem is with both banks, I did get a bank 1 code in the pending section once before. A few days ago the light came on again but this time it was during normal cruising and was 2 codes for bank 1&2 lean. I am suspecting a bad fuel pump at this point because the fuel filter was pretty nasty and can only imagine what the fuel pump sock looks like. I fixed the manifold gasket leaks and verified that they are sealed up with brake cleaner while idling. Also if it were a vacuum leak causing the codes wouldn't my fuel trims go DOWN closer to 0 when accelerating? My fuel trims steadily get more + with load. I have a elm327 cable coming in the mail today so I can use forscan on my laptop. The scanner I have been using is very old and doesn't have many options for looking at data. As far as misfires I don't think I have any but will investigate more with forscan.

As of right now my long term fuel trims for bank 1 and 2 are around 10% at idle and increase to 22-25% while driving. Short term trims are between 0-3% at idle and jump all over the place while driving but always positive.

 

[Kyleag89]

That honestly doesn't matter. A Lean condition is unmetered air, which means are PAST the MAF sensor. I don't care how much air you give it before the sensor (hood scoop, ram air, NO hood, doesn't matter). You need to verify you have the correct fuel map corresponding to the CFM and diameter of the opening the MAF lives in. I still think you need a reflashed tune to the BBK

According to BBK and American Muscle the intake does NOT require a tune. Knowing more information about this issue now I agree it's not an intake issue but either a vacuum leak or most likely a fuel delivery issue.