Horribele Gas Mileage After Repairs at Dealer

A year ago, my truck developed a violent vibration in the driveshaft. I took it in to the dealer and after it was all said and done, I got the driveshaft rebuilt, new lower control arms, power steering rack rebuilt, and new tires. Immediately after I got the truck back I noticed a significant drop in gas mileage. Before I was averaging 17-18 city. Now I get 12-14 mpg city. I've tried everything over the past year to improve it and I'm stuck. A buddy of mine suggested the dealer could have put a new program on my ECU that would cause the bad gas mileage. Reason being I have a high mileage 2nd Gen (155,000 miles), and they want me to trade it in for a new one, so they reflash my ECU so the truck now gets bad mileage. Does this seem far fetched? Looking for some advice on what to do here, because if I go to the dealer and describe my problem, I won't get a solution or honest answer about my problem.

 

I believe there was an ECU update that was applied to some trucks.
I don't know if yours is one of them. But it had to do with shift points.
This could be the issue. But it shouldn't cause a 3+ mpg lose.

I also recall some people saying the new trucks had a an ECU program for engine ping on lower octane. I don't think this will apply to your truck?
But you could look.

You say you got new tires. This could cause your issues if they are heavier and have more rolling resistance then the previous tires?

I don't honestly believe the dealer would do any thing maliciously to your truck.

I get letters in the mail all the time wanting me to trade in my current truck.
They even have the year and VIN # on the letter. My truck is always in high demand and they are willing to give me full trade in or retail on it.
I toss the letter in the trash. They just want your money you'll have to give on the new truck.

 

I would not be shocked if they manipulated the ECU.

Waiting a year to consider going back to the dealer for the issue is not in your favor.

 

You may need to seek professional help for your paranoia. Your Buddy also needs help. Seriously. Do you really think this?

Look into a tune up maybe.

 

I know its not the tires because the new ones are Passenger load tires and the previous set was load E. Are dealers the only places that can update or flash my ECU?

 

Bush did 9/11!!!

 

http://www.bullydog.com/search_vehicle.php?make=18&model=193&year=2005&engine=82&vehicle=Go

 

Haha, there's one way

 

This isn't Tacoma related, but my last car was a VW Jetta. I took it to the dealer for the 40,000 mile service. After that service, I would get 2 weeks of driving per tank, which was worse than prior to the service. I eventually changed the oil myself, and then got 3 weeks of driving per tank. Same driving habits, same miles per week, same weekly errands.

So, I can't answer why, but this was my only related experience with the issue.