Ok guys, here is it. I have searched and found the P0172/175 codes on this forum. However, they were accompanied with other codes. Here is my situation.


My scan tool indicates almost 55% alcohol content, I am thinking this is too high. I threw P0172&175 showing LTFuel too rich on both banks only. I cleared the codes my LTFuel in live mode shows 22.4% & 24.2% at idle. As I increase RPM (as I drive)(stay the same if just pressing accelerator) they go down.
I have checked pressure off of the Fuel Tracks 58psi, and held for several min. Brake cleaner for vacuum leaks around intake manifold, and EVAP hose nothing changed in engine RPM or sound. Cleaned Mass Air Flow sensor and tested it, seems to work fine.


Q1. If my Alcohol content is that high do I need to get to the dealer and have them reset it to OEM?




Q2. Do the decrease in LTFuel as RPM go up indicate vaccume leak? I would think it would be too lean with more air entering system.




The only thing I can think is that I added fuel injection cleaner a few months to a tank of gas and I am thinking that is when I started having problems but I cannot remember for sure. Also, I have never put in E85.


Thanks,
Kevin

 

Bump!


Really no one can give me an idea? I have determined that I just need the ECM re calibrated. Apparently dealership is the only one who can do this. Problem they all want $130 just to look at it. This is irritating first of all that this happened, second that they want this much for a 30sec job.


Suggestions, Ideas?


Thanks,

 

Sounds like you'll either have to bite the bullet since only a dealer can do it or find someone with a gm tech II programmer that will do it for cheaper. Or you could buy your own programmer which would cost way more than the first 2 options. Sorry brah.

 

so it's 110 proof?

is that accurate?

 

The reading is 57% Alch trim. I am taking it into the stealership today for an ECM re-flash back to OEM standards.

 

Dealership only charged me $65 for the re-flash and it worked.... for about 10 miles. I checked it when I returned to my in-laws house 3%, then I checked it 300 miles later 57% and LT Fuel Trim was back to -24%.


What could be causing this?

 

I would try getting your gasoline from a different station... even consider marine gas that is 100% gas no alcohol....
Its a "free" place to start...

 

I have had at least 25 tankful's of gas since this has first occurred. Mostly from Costco and Fred Meyer, but others as well. I recently put 5-6 gallons of premium gas 91 octane and my "alcohol fuel percentage went up to 62%.


Geez.

 

25 tank fills should rule out any anomalies in fuel....
It might be time to consider replacing the sensor if the re-set doesn't help...

 

Ok so I hooked up my scanner to another 5.3l engine of the same year. Mine is an 07 Suburban and my brother-in-law has an 07 Yukon XL.


I compared each scan and here is what sticks out.


Alcohol Fuel Percentage 62% mine
Alcohol Fuel Percentage 10.2% his


Oxygen Sensor Out put Voltage Bank 1- Sensor 1 (V) 0.320 Mine .085 his
Short Term Fuel Trim Bank 1 Sensor - 1(%) .08 Mine His 3.1


Oxygen Sensor Out put Voltage Bank 1- Sensor 2 (V) 0.075 Mine 0.535 his
Short Term Fuel Trim Bank 1 Sensor - 2(%) N/A


Oxygen Sensor Out put Voltage Bank 2- Sensor 1 (V) 0.645 Mine 0.090 his
Short Term Fuel Trim Bank 2 Sensor - 1(%) 0.8 Mine his 2.3


Oxygen Sensor Out put Voltage Bank 2- Sensor 2 (V) 0.155 Mine 0.115 his
Short Term Fuel Trim Bank 2 Sensor - 2(%) 99.2 Mine 99.2 his


So could someone tell me what OEM % are supposed to be? Or how about if you see something glaring what it would be?


Thanks,