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roosterk0031 · 10-18-2018, 05:00 PM

ECU targets stoich. O2 sensor is just watching for no excess O2 and will adjust Long term fuel trim as required.

Since it takes less air for complete combustion the car thinks it's injection to much fuel per the volume of air. So the LTFT goes positive relative to what it would be for E0-10 for the amount of air the MAF is seeing. Somewhere around +25 it will throw a Lean code P0171, even though it probably isn't.

FFV cars can have an advantage because the can learn or use a sensor to detect the E content and change timing and other tables to optimize it. Tuners who have looked at some of GM's FFV tables don't think they tried very hard to get the most out of the fuel at least in 8+ year old ones.

The impala doesn't have a sensor, after a refueling event to goes through a learn procedure to figure out the E content, your supposed to drive a certain time or distance after refueling or it might not work.

My XFE had an intermittent failure of a fuel injector recently, since at times it wasn't injecting any thing. O2 sensor saw free O2, cranked up the LTFT to 28, STFT to 32 giving me a P0171 and flooded the other 3 cylinders causing a misfire. Took a few weeks to figure out, started with O2 sensor ($35), plugs and coils $125, finally injectors for $113. Not bad for just hitting 250,000 last week.

10-18-2018, 05:00 PM	#16 (permalink)
roosterk0031 Master EcoModder Join Date: Jan 2011 Location: na Posts: 1,025 Thanks: 277 Thanked 218 Times in 185 Posts	ECU targets stoich. O2 sensor is just watching for no excess O2 and will adjust Long term fuel trim as required. Since it takes less air for complete combustion the car thinks it's injection to much fuel per the volume of air. So the LTFT goes positive relative to what it would be for E0-10 for the amount of air the MAF is seeing. Somewhere around +25 it will throw a Lean code P0171, even though it probably isn't. FFV cars can have an advantage because the can learn or use a sensor to detect the E content and change timing and other tables to optimize it. Tuners who have looked at some of GM's FFV tables don't think they tried very hard to get the most out of the fuel at least in 8+ year old ones. The impala doesn't have a sensor, after a refueling event to goes through a learn procedure to figure out the E content, your supposed to drive a certain time or distance after refueling or it might not work. My XFE had an intermittent failure of a fuel injector recently, since at times it wasn't injecting any thing. O2 sensor saw free O2, cranked up the LTFT to 28, STFT to 32 giving me a P0171 and flooded the other 3 cylinders causing a misfire. Took a few weeks to figure out, started with O2 sensor ($35), plugs and coils $125, finally injectors for $113. Not bad for just hitting 250,000 last week. Last edited by roosterk0031; 10-18-2018 at 05:06 PM..