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ECM relay replacement- fuel mileage

4K views 7 replies 4 participants last post by  Tramsey4 
#1 ·
I don't know if it's just me or what but ever since the dealership replaced my ecm relay, my gas mileage has dropped 1.5-2 mpg. My driving habits have not changed, I don't believe the gas mixture at the pump has changed, and everything on my truck is well serviced.

Could this be the problem? If so is there a way to "reset" or something to get back my mpg?
 
#3 ·
The only thing that same day was a window motor replacement.
I just ordered a K&N air filter and will be getting some fuel injector cleaner.
The last thing I can think of is resetting the ECU and flashing the memory.
That's why I was wondering if it could be the ecm relay.
 
#5 ·
The replaced it a few weeks ago. I calculate with miles/gallons at fill up. I don't top off. When it stops pumping then that's when I calculate. Before the ecm relay was replaced due to recall I was getting about 21.4. My fill ups after the install are 20.6, 20.1, 19.6. After noticing being under 20mpg I have become concerned. I used to get 400 on a tank and I'm getting to 350ish now.
 
#6 ·
They may have reflashed or cleared the computer. It will take several hundred miles of driving for the computer to relearn the fuel curves.

And return that K&N crap. You won't gain any performance, it'll pass much more dirt, and possibly contaminate your MAF sensor.
 
#8 ·
After driving about 400 miles it seems to be increasing back up. Unfortunately I was stuck in traffic for an hour idling so I couldn't get a good idea what my mpg was. I ended up with 20.6 with 80% highway.
I know the k&n filter is not a miracle add-on. I do notice a bit more power on take off.
 
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