Just an fyi a clogged fuel injector can definitely cause a rich condition because if the injector cannot spray the fuel in a fine mist it won't combust, and if it drips out there will be allot unburned fuel in there and the o2s will read that
Great video. I've had rough cold starts and been clearing bank too rich codes all week. I decided to run a log and noticed alcohol content was at 80%. This video was the first to come up on google and, what do you know, it's the exact same issue. I guess I'll be resetting the fuel composition and trim.
I've been having this issue for 4 years.. I drive back and forth from Iowa to Colorado 2x every year, and every time I get back to Colorado it starts misfiring, and I have to get the composition reset every time. I wish there was an easier way to just do it, similar to resetting the oil life...
I’ve been chasing this problem for a while now been resetting the alcohol content reading 70.1% which is running both banks really rich and we don’t have e85 here in timmins. I always put 87 octane in my tank and seems that all my 02 sensors are reading perfect, mass air flow sensor is working and also cleaned it. I’m trying to figure out why this keeps happening I’m not sure what else to look at from this point on, I have a 2011 Silverado 1500 4.8 flex fuel. If you can help me out on that it’d be very much appreciated thanks.
There is a tsb number PIP4792D that suggests there may be a PCM update to address the incorrectly learned alcohol content. I'd make sure you have the most up to date program in the PCM. Are the forward O2 sensors original equipment or aftermarket?
I had a throttle body relearn done to fix the constant problem after cleaning it. I think I may have made a mistake I did a fuel composition reset using X431 on my 2011 5.3 flex fuel suburban , currently have e85 in my tank. Now I have 2 code errors p0171-00 and p0174-00 fuel trim lean system lean bank 1 and 2. Did I do something wrong? I would appreciate any help what to do and proceed. Thank you
Not really. If you do the composition relearn it assumes you are not running E85 or some ratio other than conventional gasoline. I believe it resetsvit to 0 or maybe 5%. If you do have E85 actually in the tank the engine actually needs 20 to 25% more fuel to run correctly. If you can add some normal gasoline to the tank. Unfortunately there is no way to manually override the fallback to 0%. If the tank is full that will be a problem. I'd remove the fuel line at the fuel rail, command the fuel pump on and pump the tank out into some fuel containers then refill with regular unleaded. Hope this helps
I'm using a Snap-on Verus Edge. I also occasionally use an Autel Maxisys Elite. If needed I have Ford IDS, GM GDS2 Chrysler Witcher and Ross Tech VCDS installed on various tablets and laptops. But in this video I'm working with the Snap-on Verus Edge.
When an engine runs rich on both banks the computer sees this due to high voltages from both forward O2 sensors. This is what causes the fuel trims to go negative. When it his approximately -25% and stays like this for a specific time that's when the codes are set. The problem is the ECM is always subtracting fuel in an attempt to correct the fueling. When the engine is cold it is still predominantly rich but it is in "Open Loop" because the O2 sensors are not working yet so at that time it would not be correcting for the rich condition. The exception to this would be when an O2 reports a false rich condition. (voltage indicates its running rich when it is not). In that situation the computer would take fuel away and it would actually be running too lean. Hope this helps.
When an engine runs rich on both banks the computer sees this due to high voltages from both forward O2 sensors. This is what causes the fuel trims to go negative. When it his approximately -25% and stays like this for a specific time that's when the codes are set. The problem is the ECM is always subtracting fuel in an attempt to correct the fueling. When the engine is cold it is still predominantly rich but it is in "Open Loop" because the O2 sensors are not working yet so at that time it would not be correcting for the rich condition. The exception to this would be when an O2 reports a false rich condition. (voltage indicates its running rich when it is not). In that situation the computer would take fuel away and it would actually be running too lean. Hope this helps.
When an engine runs rich on both banks the computer sees this due to high voltages from both forward O2 sensors. This is what causes the fuel trims to go negative. When it his approximately -25% and stays like this for a specific time that's when the codes are set. The problem is the ECM is always subtracting fuel in an attempt to correct the fueling. When the engine is cold it is still predominantly rich but it is in "Open Loop" because the O2 sensors are not working yet so at that time it would not be correcting for the rich condition. The exception to this would be when an O2 reports a false rich condition. (voltage indicates its running rich when it is not). In that situation the computer would take fuel away and it would actually be running too lean. Hope this helps.
![MAF and Wideband O2 Sensor Testing for a P0172 [Rich Condition]](http://i.ytimg.com/vi/_z6HoW4OiD8/mqdefault.jpg)
![MAF and Wideband O2 Sensor Testing for a P0172 [Rich Condition]](/img/tr.png)
Just an fyi a clogged fuel injector can definitely cause a rich condition because if the injector cannot spray the fuel in a fine mist it won't combust, and if it drips out there will be allot unburned fuel in there and the o2s will read that
Great video. I've had rough cold starts and been clearing bank too rich codes all week. I decided to run a log and noticed alcohol content was at 80%. This video was the first to come up on google and, what do you know, it's the exact same issue. I guess I'll be resetting the fuel composition and trim.
Thanks for watching. Let me know if resetting the fuel composition fixes your issue. I'll bet your fuel economy sucks like that...
I've been having this issue for 4 years.. I drive back and forth from Iowa to Colorado 2x every year, and every time I get back to Colorado it starts misfiring, and I have to get the composition reset every time. I wish there was an easier way to just do it, similar to resetting the oil life...
I’ve been chasing this problem for a while now been resetting the alcohol content reading 70.1% which is running both banks really rich and we don’t have e85 here in timmins. I always put 87 octane in my tank and seems that all my 02 sensors are reading perfect, mass air flow sensor is working and also cleaned it. I’m trying to figure out why this keeps happening I’m not sure what else to look at from this point on, I have a 2011 Silverado 1500 4.8 flex fuel. If you can help me out on that it’d be very much appreciated thanks.
There is a tsb number PIP4792D
that suggests there may be a PCM update to address the incorrectly learned alcohol content. I'd make sure you have the most up to date program in the PCM. Are the forward O2 sensors original equipment or aftermarket?
@@PhillipBailey thanks for the quick response, I did get my ecm flashed and got the latest version put in, my o2 sensors are genuine not aftermarket.
I had a throttle body relearn done to fix the constant problem after cleaning it. I think I may have made a mistake I did a fuel composition reset using X431 on my 2011 5.3 flex fuel suburban , currently have e85 in my tank. Now I have 2 code errors p0171-00 and p0174-00 fuel trim lean system lean bank 1 and 2. Did I do something wrong? I would appreciate any help what to do and proceed. Thank you
Not really. If you do the composition relearn it assumes you are not running E85 or some ratio other than conventional gasoline. I believe it resetsvit to 0 or maybe 5%. If you do have E85 actually in the tank the engine actually needs 20 to 25% more fuel to run correctly. If you can add some normal gasoline to the tank. Unfortunately there is no way to manually override the fallback to 0%. If the tank is full that will be a problem. I'd remove the fuel line at the fuel rail, command the fuel pump on and pump the tank out into some fuel containers then refill with regular unleaded. Hope this helps
Good repair. So dumb to guess alcohol content.
Great content love your video.
What machine you using to read the cars ?
I'm using a Snap-on Verus Edge. I also occasionally use an Autel Maxisys Elite. If needed I have Ford IDS, GM GDS2 Chrysler Witcher and Ross Tech VCDS installed on various tablets and laptops. But in this video I'm working with the Snap-on Verus Edge.
If it's taking fuel away how is the gas mileage going to be bad?
When an engine runs rich on both banks the computer sees this due to high voltages from both forward O2 sensors. This is what causes the fuel trims to go negative. When it his approximately -25% and stays like this for a specific time that's when the codes are set. The problem is the ECM is always subtracting fuel in an attempt to correct the fueling. When the engine is cold it is still predominantly rich but it is in "Open Loop" because the O2 sensors are not working yet so at that time it would not be correcting for the rich condition. The exception to this would be when an O2 reports a false rich condition. (voltage indicates its running rich when it is not). In that situation the computer would take fuel away and it would actually be running too lean. Hope this helps.
When an engine runs rich on both banks the computer sees this due to high voltages from both forward O2 sensors. This is what causes the fuel trims to go negative. When it his approximately -25% and stays like this for a specific time that's when the codes are set. The problem is the ECM is always subtracting fuel in an attempt to correct the fueling. When the engine is cold it is still predominantly rich but it is in "Open Loop" because the O2 sensors are not working yet so at that time it would not be correcting for the rich condition. The exception to this would be when an O2 reports a false rich condition. (voltage indicates its running rich when it is not). In that situation the computer would take fuel away and it would actually be running too lean. Hope this helps.
When an engine runs rich on both banks the computer sees this due to high voltages from both forward O2 sensors. This is what causes the fuel trims to go negative. When it his approximately -25% and stays like this for a specific time that's when the codes are set. The problem is the ECM is always subtracting fuel in an attempt to correct the fueling. When the engine is cold it is still predominantly rich but it is in "Open Loop" because the O2 sensors are not working yet so at that time it would not be correcting for the rich condition. The exception to this would be when an O2 reports a false rich condition. (voltage indicates its running rich when it is not). In that situation the computer would take fuel away and it would actually be running too lean. Hope this helps.