P0172 & P0175 07 Silverado 5.3L
06-13-2013, 11:20 PM
#1
Teching In
Thread Starter
Join Date: Nov 2010
Location: orange county, CA
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
P0172 & P0175 07 Silverado 5.3L Hello all,
I have a 2007 Silverado (classic body) 5.3L, 2wd, Auto Trans
P0172 & P0175 stored and long term FT @ -19.5% both banks.
Truck is bone stock with 70k miles on it.
Starts, runs, idles, drives just fine.
Air filter is new ac delco.
Fuel pressure is 60psi.
Both upstream sensors appear to be switching.
Swapped known good MAF and MAP sensors.
Tried clearing codes with scan tool and tried the battery cable reset after sensors replaced...no change.
Any ideas out there??
thanx
I have a 2007 Silverado (classic body) 5.3L, 2wd, Auto Trans
P0172 & P0175 stored and long term FT @ -19.5% both banks.
Truck is bone stock with 70k miles on it.
Starts, runs, idles, drives just fine.
Air filter is new ac delco.
Fuel pressure is 60psi.
Both upstream sensors appear to be switching.
Swapped known good MAF and MAP sensors.
Tried clearing codes with scan tool and tried the battery cable reset after sensors replaced...no change.
Any ideas out there??
thanx
06-14-2013, 12:17 AM
#4
I just went through the same thing on a 07 Classic FF truck. FF vehicles command richer A/F ratios based on perceived alcohol content in the fuel. The PCM was commanding a 12.5:1 A/F ratio in closed loop on 100% gas. No ethanol. We still have 100% gas in Okla. There is no alcohol sensor on a 07 FF truck. The PCM tries to determine alcohol content by O2 sensor output. 12.5:1 equates to about 35% alcohol content. With 100% gas that drives the trims way negative. The owner of the truck is a GM Dealer tech and was having to reset the alcohol content to 0 with his tech 2 and over about a week of driving the commanded A/F would creep back to 12.5:1 and way -trims. The only fix we could come up with was to turn off the flex fuel option in the tune. See if you can get a hold of a scanner that will display commanded A/F and see if this is your problem. I've seen this same problem on other GM FF vehicles that don't have the alcohol sensor.
