I posted about this earlier, the RPM drop, knocking, and white smoke... it was interesting seeing where somer had their engines replaced. I hooked my truck up to the $5k snapon diagnostic computer, and it shows "ethanol mode off" and "ethanol learn mode disabled"... Not having ,uch luck finding anything out about these... has anyone found these before, or know how to turn them both ON? That might help, with all of the ethanol in the gasoline these days...

09 1500, Quad Cab, 4.7L Flex, 2WD

 

I thought it was an automatic thing for the pcm to know if you have ethanol in your tank or not? Is there maybe a bad sensor somewhere?

If you cannot diagnose the problem and dont want to go to the Dealer, I'd say put in regular gaoline.
Ethanol doesn't save any money. I've calculated it out a few times. While it seems cheap at the pump, it burns quicker and you get less mpg's as well. The combination of the 2 cost the same as if you put regular gas in plus you dont get the excessive wear from ethanol(brittle seals, dried plastics..etc) even though they are "made" for ethanol. It still happens.

Sorry I couldnt help better on your actual problem.

 

The mechanic and I were thinking that if it were disabled in the PCM, and not adjusting for the percentage of ethanol in the regular gasoline, it might be causing the ignition issues. when i get the symptoms, the engine is acting like it is missing on a cylinder completely, dumping the unburned, vaporized fuel out into the exhaust... I think i will try a test drive with the computer displaying the real-time info from the PCM, see what happens...

 

The 4.7 is a flex fuel engine, doesn't make any sense that ethanol mode could be off. Take it to the dealer and have them look at it.

 

talked to them yesterday, they said its automatic. I asked why the learning mode would be disabled, and i swear i heard crickets chirping...

 

Sounds like a blown headgasket, which is not that uncommon for the 4.7

 

if it was a blown head gasket, wouldn't I see some drop in oil level? Wouldnt the issue be a constant thing? I'm not leaking any oil externally, not losing any oil or coolant (i put a LOT of highway miles on this baby, I'm always checking fluids).... When they worked on it originally (the dealer) they said i had a "melted ignition coil". if this is true, and i have another one, what could be burning out the coils?

LU, im not trying to down what youre saying, im honestly asking...

 

You can pretty easily blow a head gasket between cylinders and never leak a drop of anything.