need some help: fault code P0174

[Jan777]

When I start the engine the yellow lights go on. The search for the fault codes gives me this:

P0174 - Powertrain
System too Lean (Bank 2)

I can deleted the fault codes and switch off the yellow lights. But when I start the engine the next time I get the same again. I do not see any difference in power, fuel consumption, sound or behavior of the engine.

What's the problem? Anyone got experience with fixing this?

thanks

Jan

 

[bigmace]

Check / clean your MAF. Make sure there are no vacuum leaks. Maybe a bad fuel injector?

 

[rwrobs777]

If this was just a Bank 2 specific DTC it would NOT be a vacuum leak or MAF sensor...a vacuum leak for instance after the MAF sensor would affect the whole engine...BOTH banks !!...you MAY also have a P0171 but that DTC might have not set yet because the fuel trims on Bank 1 haven't reached the limit to set that code...if you have a scan tool I can have you look at some numbers and possibly diagnose it for you...it can be a "no spark" or no "injector pulse" or a bad injector but that usually sets a misfire code P03XX-030XX. I'm usually on the Corvette forum but these 4Runners never have driveabilty issues...LOL !!...I spent this past Saturday helping a Forum member who had "rich" codes instead of the lean ones you are experiencing...found out 4 injectors were bad !!

 

[earthrealm]

If this was just a Bank 2 specific DTC it would NOT be a vacuum leak or MAF sensor...a vacuum leak for instance after the MAF sensor would affect the whole engine...BOTH banks !!...you MAY also have a P0171 but that DTC might have not set yet because the fuel trims on Bank 1 haven't reached the limit to set that code...if you have a scan tool I can have you look at some numbers and possibly diagnose it for you...it can be a "no spark" or no "injector pulse" or a bad injector but that usually sets a misfire code P03XX-030XX. I'm usually on the Corvette forum but these 4Runners never have driveabilty issues...LOL !!...I spent this past Saturday helping a Forum member who had "rich" codes instead of the lean ones you are experiencing...found out 4 injectors were bad !!

i have the same problem, my LTFT bank 2 is 37%, and LTFT bank 1 is 17%, i have only p0174, no pending p0171, though sometimes if i accelerate aggresively i sometimes get p0430 - catalytic converter code, cleaned maf and TB, no change. thinking it may be the fuel pump, but want to do a pressure test first, cannot seem to locate the service port:target:

 

[rwrobs777]

i have the same problem, my LTFT bank 2 is 37%, and LTFT bank 1 is 17%, i have only p0174, no pending p0171, though sometimes if i accelerate aggresively i sometimes get p0430 - catalytic converter code, cleaned maf and TB, no change. thinking it may be the fuel pump, but want to do a pressure test first, cannot seem to locate the service port:target:

I don't know what percentage the LTFT will throw a DTC but Bank 1 is high and bank 2 is WAY high...anything over 10% is no good...I'm assuming you have a scan tool....what does the stft's do when you run the RPM at 3000 RPM ??...if short terms go negative...towards zero you most likely have a vacuum leak somewhere...it takes the long terms a little longer to come down...if long terms and short terms increase you have a fueling issue (fuel pump) OR a MAF sensor issue...I have a 2016 and unfortunately I don't think I have a Schrader valve on my fuel rail like on my 2001 Corvette !!...does your scan tool show "freeze frame" info...it may also be in mode 6...at least you can see if the 0171 set at idle or a higher RPM !!

 

[earthrealm]

I don't know what percentage the LTFT will throw a DTC but Bank 1 is high and bank 2 is WAY high...anything over 10% is no good...I'm assuming you have a scan tool....what does the stft's do when you run the RPM at 3000 RPM ??...if short terms go negative...towards zero you most likely have a vacuum leak somewhere...it takes the long terms a little longer to come down...if long terms and short terms increase you have a fueling issue (fuel pump) OR a MAF sensor issue...I have a 2016 and unfortunately I don't think I have a Schrader valve on my fuel rail like on my 2001 Corvette !!...does your scan tool show "freeze frame" info...it may also be in mode 6...at least you can see if the 0171 set at idle or a higher RPM !!

below is my freeze frame data.

Freeze frame report generated by Torque for Android
================================================== =======

Vehicle VIN: JTEBUXXXXXXXXXXXXXX
Vehicle Manufacturer: Toyota
Vehicle Calibration ID: 33535000

Freeze frame information:
------------------
Fuel Trim Bank 1 Short Term = -1.562 %
Fuel Trim Bank 1 Long Term = 14.062 %
Fuel Trim Bank 2 Short Term = 0.781 %
Fuel Trim Bank 2 Long Term = 37.5 %
Engine RPM = 875 rpm
Speed (OBD) = 7.456 mph
Timing Advance = 15 °
Intake Air Temperature = 123.8 °F
Mass Air Flow Rate = 6.62 g/s
Throttle Position(Manifold) = 17.255 %
Run time since engine start = 133 s
O2 Sensor1 Equivalence Ratio = 1.004
O2 Sensor5 Equivalence Ratio = 0.995
Distance travelled since codes cleared = 1.243 miles
Barometric pressure (from vehicle) = 14.504 psi
Catalyst Temperature (Bank 1,Sensor 1) = 839.3 °F
Catalyst Temperature (Bank 2,Sensor 1) = 839.3 °F
Catalyst Temperature (Bank 1,Sensor 2) = 247.64 °F
Catalyst Temperature (Bank 2,Sensor 2) = 247.64 °F
Voltage (Control Module) = 13.164 V
Engine Load(Absolute) = 18.824 %
Commanded Equivalence Ratio(lambda) = 1.005
Relative Throttle Position = 0 %
Absolute Throttle Position B = 49.02 %
Accelerator PedalPosition D = 16.078 %
Accelerator PedalPosition E = 32.157 %


End of report.

__________________

 

[earthrealm]

I don't know what percentage the LTFT will throw a DTC but Bank 1 is high and bank 2 is WAY high...anything over 10% is no good...I'm assuming you have a scan tool....what does the stft's do when you run the RPM at 3000 RPM ??...if short terms go negative...towards zero you most likely have a vacuum leak somewhere...it takes the long terms a little longer to come down...if long terms and short terms increase you have a fueling issue (fuel pump) OR a MAF sensor issue...I have a 2016 and unfortunately I don't think I have a Schrader valve on my fuel rail like on my 2001 Corvette !!...does your scan tool show "freeze frame" info...it may also be in mode 6...at least you can see if the 0171 set at idle or a higher RPM !!

@3000rpm, the LTFT2 goes down a couple of digits to about 32%, nothing serious happenes to the other parameters, noticed a few times after disconnecting the battery, i get a p0304 misfire error, i cclear it with the scan toool, and it doesnt come back.
what do you think?

 

[Bossman]

Maybe some tips/suggestions in these 4th Gen threads:

P0174

P0174, Rough Idle & Strong Exhaust Smell

Help needed- Fuel pressure test persistent p0174

 

[Deep_palancar]

@3000rpm, the LTFT2 goes down a couple of digits to about 32%, nothing serious happenes to the other parameters, noticed a few times after disconnecting the battery, i get a p0304 misfire error, i cclear it with the scan toool, and it doesnt come back.
what do you think?

35% Longtrim is the threshold for code set. One sided lean with an occasional misfire calls for injector cleaning. Real remove and clean or renewed swap-out. Miracle in bottle might help but it will take time.
IAT of 123.8° ?is that right?
FWIW there is no fuel pressure test port. You have to Y-fitting in somewhere. As others have said, pressure problems are not going show one-sided DTC and tend to show up power demand related.

 

[earthrealm]

35% Longtrim is the threshold for code set. One sided lean with an occasional misfire calls for injector cleaning. Real remove and clean or renewed swap-out. Miracle in bottle might help but it will take time.
IAT of 123.8° ?is that right?
FWIW there is no fuel pressure test port. You have to Y-fitting in somewhere. As others have said, pressure problems are not going show one-sided DTC and tend to show up power demand related.

been running mobil injector cleaner for a while now, no change.
oem injectors are quite pricey, and am unsure if remanned injectors are worth buying....and now it throws p0430 code on highway drives
real PITA!

 

[Mutant138]

What year? How many miles? Just for data's sake.

 

[earthrealm]

05, V6, 4WD. About 170k miles

 

[4R4Trout]

I have seen similar codes on a 2006 GMC Yukon after installing a K&N drop in oiled filter. Fuel mileage tanked in addition to the code. I re-installed the stock air filter, cleaned the MAS and never got the code again. Fuel mileage came up too. Never again K&N.

 

[earthrealm]

I have seen similar codes on a 2006 GMC Yukon after installing a K&N drop in oiled filter. Fuel mileage tanked in addition to the code. I re-installed the stock air filter, cleaned the MAS and never got the code again. Fuel mileage came up too. Never again K&N.

I have stock air filter, never messed with it, for some years prior to this, LTFT1 has been 8%, LTFT 2 18%, no cel, the cel just came up a couple of months ago, fixing to remove the injectors and service, trawled youtube and the forum, no detailed video or picture of the process.

have you come across any?

 

[earthrealm]

swapped all the injectors with ebay remanns, CEL gone, fuel trims ok now. am super stoked!!!