P0172, P0175 too rich, 07 6.2 about to throw in the towel

[chucksrt]

I have a 07 Yukon denali xl with 120,000 miles on it. I started getting a check engine light a month or two ago. I researched it and replaced items that are common to causing this issue. I didn't care if it was the fault or not because of the miles i just figured the new parts would help it regardless. I started by replacing the EVAP purge solenoid. That actually seemed to help me fill the tank to full better? I then replaced the mass air flow sensor, again, i have cleaned it but thought a new one wouldn't hurt. Then i replaced the MAP sensor. I know that they can be a common point of failure. It seemed to run better but still had the C.E.L. i took it to a friends shop and he wasn't much help. He pretty much looked it up on Mitchell and said it sounds like the fuel injectors are bad. I bought a used set of injectors and sent then to FIC to be cleaned and flow tested. I received them yesterday and installed them and on my maiden voyage the codes returned in pending. I am at a loss!? I am going to take it to GMC to look at ir bur i do not know what else to check. Any thoughts or have you run into a similar issue where something else fixed it?

 

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[chucksrt]

Have your filling issues gone away?

I have not gilled up since. I was afraid to fill up then have to drop the tank to replace the fuel pump.

 

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[chucksrt]

The stabilitrack light coming on just tells me that a code just set in pending. In this case the code that set was for the P0172, P0175. If it ends up being a worn engine issue then i will take it back to the dealer because my extended warranty covers that. I don't feel as if i have any loss of power while driving and i would like to think that thecodes are related to the hard start but i am pretty sure they are two different issues. But i am not really familiar with this returnless fuel system.

 

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[Jsdirt]

Something to think about ...

 

Rich codes that never go away are also a sign of a worn out engine. I'd do a compression & leak down test at this stage to see where you're at - compression at the very least. Hard starting & a rough idle go hand in hand with low compression.

 

Stabilitrak codes are unrelated to this - normally ABS issues, or steering position sensor problems will cause that. A very common issue with these.

[chucksrt]

The scantool was delivered today! Just meed to get home to check it. I hope it shows the fuel pressure sensor reading (it is kinda a cheepy scantool) Autel AL619 scantool.

 

Another odd issue that may or may not be related. My fuel used gauge always says a different amount than the amount of fuel i actually used. If the guage says i used 21 gallons when i fill up it will take 26 gallons to fill it.

 

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[txab]

Will not show fuel pressure reading. You need to attach FPR gauge to the port on the fuel rail

[wildcatter]

The safety lock on the GM spares are awful. The lock is supposed to release when you crank the wheel up. They always stick. I have gotten some to release by cranking the wheel up and whack the end of the winch cable that holds the rim.Use a hammer.That will usually jar the lock loose so it can be winched down.Good luck. I have had to cut the cable with a torch a time or two.

[Jsdirt]

Yep - just about all of them come down with the fire wrench in this part of the country.

[chucksrt]

As far as the running / starting problems go, you could have a bad "new" MAF sensor. At this stage, that seems to be the only suspect component. Need a multimeter that reads Hz (Hertz) to properly diagnose.

 

Here ya go: http://easyautodiagnostics.com/gm/4.8L-5.3L-6.0L/testing-the-maf-sensor-1

Awesome link. I am pretty sure my meter does hz. I am also going to pick up a fuel pressure guage today.

 

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[Jsdirt]

I believe the regulator on that system is part of the pump assembly in the tank, since it's a single-line system. You could've had a bad regulator that was allowing excessive fuel pressure to the rail - I can't remember if you checked the fuel pressure or not prior ...

 

Either way, glad to hear you've made headway on this one!

[chucksrt]

Regulator is in the tank on this one. Single line - returnless system, non-DI. The data here just confirms the rich condition, but doesn't tell us much else.

 

Is this a flex vehicle? I don't see it in the parameters, so I don't know if that's the fault of the tool, or that the truck isn't flex ...

It is not a flex vehicle. The fuel tank pressure sensor, coolant semsor and the o2 sensors are the only things i haven't replaced. The o2's seem to be switching when checking live data. I did not pay notice to the coolant temp readings.

 

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[chucksrt]

Freeze data for P0175

Fuel sys 1 status CL

Fuel sys 2 status CL

Calc load value 69.0%

Coolant temp 140 F°

 

Short term fuel trim bank 1 -8.6%

Long term fuel trim bank 1 -20.3%

Short term fuel trim bank 2 -9.4%

Long term fuel trim bank 2 -20.3%

Intake MAP 13.1psi

Engine RPM 2133rpm

Vehicle speed sensor 32 mph

Ignition timing advance cyl #1 31.5°

Intake air temp 55°F

Air flow rate MAF 0.16 lb/s

Throttle position 42.7%

Time since engine start 132 sec

Commanded evap purge 0.0%

Fuel level input 51.8%

Evap system vapor pressure -0.138 inH2o

Barometric pressure 14.9 psi

Catalyst temp bank 1 1179°F

Catalyst temp bank 2 1359°F

Load value 56.9%

Commanded equivalence ratio 0.999

Relative throttle position 28.6%

Ambient air temp 54°F

Absolute throttle position B 42.7%

Accelerator pedal pos D 37.3%

Accelerator pedal pos E 18.0%

Commanded throttle actuator control 41.2%

 

 

 

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