MPG Issues for my Ford Police Interceptor Utility 11 MPG

Jul 26, 2023
2017 FPIU

Update: Went back to the Ford Dealer for help. They said there’s nothing they can do for MPG issues. They said we could waste your money but it’s a waste. At least they didn’t rob me. They suggested I NOT use costco gas and put in 87 at Shell. My pops (80 year old mechanic) thinks that is nonsense that Costco has the best gas.

Update: Paid $450 to fix/weld the cracked Catalytic Converter. Didn’t seem to fix the MPG issues sadly.

Update: I have a cracked Catalytic Converter at the flange. That might be a possible reason.

Original: The best I’ve ever done with this thing is 17.5 or 20 on a TRIP. Which is great except after I got my waterpump changed, it dropped down to 8 MPG. I went to a shop 2x, and the Ford Dealer, and both found nothing to fix. Somehow changing the water pump lost 3mpg. After $1,200 I’ve got it up to nearly 12 but it’s supposed to be like 14-17 minimum. I have the worst MPG in the entire US for a 3.5L. They had a top 10 list of worst SUV MPG and mine is even worse than that. Top 10 Pickups With the Worst Fuel Economy – MotorTrend

I spent $900 on a tuner, 3map, temp. The thermostat isn’t installed and they wanted $200 to install it and said it would make the MPG less, but the creators said it wouldn’t. I didn’t get the cold air intake.

Some things I’ve done:

  • New Spark Plugs
  • PTU Fluid Change
  • Multi-point inspection
  • Gas changed to 91 or 87 (no effect)
  • Tires (two were leaking, fixed)
  • Rear differential fluid change
  • Dumped in (3) Chevron 65740-CASE Techron Concentrate Plus Fuel System Cleaner. Improves a LITTLE but then goes back.
  • Oil Change

Possible other things to try when I get more money:

  • Walnut Blasting/Carbon Cleaning. Supposedly it builds up carbon
  • Maybe O2 Sensor Change.
  • Fuel Pump replacement

Performance Tuning Package $900

$600 Tuning Device

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3 BAR MAP SENSOR
Manifold Absolute Pressure (MAP) sensors, have two specific responsibilities in the engine management system: measuring barometric pressure at key on, and to report engine load to the powertrain control module. The powertrain control module uses the information for proper air/fuel mixture control under performance driving conditions. For example, a 3 BAR sensor will handle a forced induction up to 29.0+ psi of boost. We use this measuring and reporting to build more powerful and more stable tunes.

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Highly recommended for any vehicle with a high performance tune, Livernois Motorsports & Engineering’s precision gapped Motorcraft spark plugs eliminate hi boost flame-out misfires on 3.5L Ecoboost cars and trucks! Replacement for all V6 Ecoboost engines. Image is a representation. Actual product received may differ.