Two weeks ago i replaced my erg valve. I uninstalled the 87 octane tune, reinstalled the stock tune, disconnected neg. battery cable. Installed new egr, reconnected neg. battery cable, installed 87 octane tune. My driving habits have not changed, i drive the same distance, nothing is different except a new egr valve. My mileage prior to install was 16-17mpg, now drops at a red light down to single digits, and then ever so slowly will get up to 14 if im lucky. What the heck is going on? I need some help, any ideas?

 

By disconnecting your battery for a time, you reset your PCM. Truck now has to re-learn adjustments for O2 and other sensor info as well as driving habits. Give it a couple of tanks of gas and you'll be right around normal for you.

 

Thanks for the quick response Hammer, I'll wait and see.