E85 Truck Running Rich

[Teal03]

I'm asking about this for my dad's truck, it is a '07classic with the E85 5.3. The gas in the truck is E10, the PCM says it has a blend of E37. Getting DTC of rich on both banks. What should we look at to replace of inspect?

 

 

Thank you,

 

Rich G.

[desrtrat]

if it is still under the power train warranty i would take it to a dealer. it is possible that the PCM may need a re flash..or he is getting a bad batch of fuel. try changing where he gets his gas and see if it clears up..

 

good luck

[minibike132]

It won't be covered under warranty.

 

http://www.gm-trucks.com/forums/index.php?showtopic=78169

[GPSilverado]

I noticed my truck was showing approx 37% ethanol as well a few months back. I do sometimes run E-85 in mine, but thought I should be back around 15 - 20% at the time. I monitored mine for a while, and only filled up with pure gas (station claims 0% ethanol in their gas) for 2 or 3 tanks, running it as low as possible. Then the last tank, I had a 5 gallon can full of the 0% gas in the bed, and ran the truck until it ran out. Once she sputtered I pulled into a parking lot, and put the 5 gallons in. I then drove on to work (more than 7 miles) and filled up when I left work, and drove the 18 miles home.

 

I checked the fuel percentage in the ECM and it showed 22% still. I took a chance and reset mine using the autocal with the efilive on my laptop. I ran that tank down to about 1/8 tank, and filled up with E85, then drove home and checked again. It showed 72%.

 

I think mine is close now. When I first started running E85 sometimes, I hadn't read the manual, and screwed up on the refueling procedure. I sometimes would drive 1/4 mile from the station to work, then cut the truck off. Now I only fill up when I leave work.

 

I wouldn't recommend doing this procedure unless you have a station that carries 0% ethanol, and you probably should run 2 or 3 tanks of this before running the truck out, refueling, and resetting the percentage in the ECM. The 2 or 3 tanks help dilute the ethanol so that what remains in the tank once it runs out will not be enough to make more than 10% ethanol when the tank is filled with 0%.

 

I figured with E85, and I leave 6 gallons before filling up, putting in 20 gallons of pure gives me 20% ethanol, then repeating gives me around 5%. So technically you could probably then fill with 0%, reset the ethanol percentage using EFILive, and be OK.

 

I am sure the dealership would charge 200.00 or more plus fuel cost to empty the tank and refill it, but I could be wrong.

 

 

I think though that even if the truck thinks the fuel is a higher percentage of ethanol than it really is, which would probably initially trigger more fuel, that the system would adjust the mixture back down based off the O2 sensor readings until the mixture was correct. I guess that doesn't mean that the ECM wouldn't set a code though based off of excessive fuel trims.