MPG after Dealer Service ???

I had to get a fuel injector replaced on my 2016 Tacoma a couple week ago

Being a creature of habit and having the "ECO" app on my touchscreen I would watch my MPG twice daily. Once on the way to work, and once on my way home.

Driving to work averaged 17mpg as it is mostly uphill.

Driving home averaged 20mpg...

I did this every day. There were times when I got better or worse mpg, depending on traffic and or how heavy my foot was that day. but 17 and 20 were super consistent.

Since having the fuel injector replaced I cannot get better than 16mpg. I may get 17mpg if I drive 60-65mph the whole time. Which doesn't work on California Freeways.

Can someone please tell me what changes the Dealer did to my Truck or to the ECU. I need to go in with good information before I take it in and have them undo what ever changes they could have made.

 

If this was done at a Toyota dealer you should have some sort of print out / record that outlines pretty well what exactly was done. Could post a picture of those page(s) here and that might help

 

Can a change in spark plug effect MPG ?

 

Be prepared for gales of laughter if you go back to the dealer looking for 1 MPG on a built in indicator.

At least give it 2-300 miles of use in case the ECU is 're-learning' your drive habits.

 

I drive 82 miles a day just for work. I'd have hit the 2-300 mile mark in 4 days..

 

This!
There's a good chance they had your truck idling (running at Zero MPGs) for a long time, before and after the fix, so the ECU/calculations are now projecting you to get worse.

EDIT: also, has anything else changed? Like new/larger tires?

 

It's driving like the ECU is making me change my driving habits. She shifts in irregular places then before, wont hold 3k rpm uiphill in 5th at 78pmh now, but will at 73pmh.. I dont know man. Wierd $#it..?

 

New tires added, but not larger

 

Did they update the software for the surging TSB?

 

Unknown ? Paper work states:
Changed plugs
Replaced 1 Injector
Flushed fuel System
Cleaned Throttle Body

 

New tires can effect MPG slightly regardless of a change in size.

 

I'll bring the pressures up a bit and drive that for a week. See what happens

 

This. Different stiffness in sidewalls, different tread pattern, different psi, all that could have tweaked your mpg.

 

They most likely rested the ECU while changing the injectors. If I am not mistaken, disconnecting the battery alone is enough to do this. Once rested, shifting points, throttle sensitivity, etc. will reset to default settings. ECU will need to relearn your habits. After the the truck should behave similar to how it was before.