if I install an after market chip to improve fuel mileage and increase horsepower will it change my shift points and cause any other problems i'm not aware of?

 

Have you realized what you just said?
Mileage and power increases don't normally go togather.
It cost fuel to make more power without any mechanical changes to the motor to increase the motor efficiency.
As to any transmission shift change, depends on what program changes were included on the chip.
Without knowing anything about the chip, you can't tell.
You buy it, have faith in the sales pitch and take a chance on the results.
Good luck.

 

Personally, I'd stay away from the chips. Your vehicle is suppose to come most efficient with the stock settings from Ford, chips just seems like a waste of money and unncecessary risk to your engine.

 

Vehicles are not always programmed for max efficiency from the factory. They are dialed in to meet a certain air fuel mixture and left there. I have installed several programmers and dyno tuned the vehicle with an air/fuel meter hooked up. Once you hit the point where you get the most power with the best air/fuel ratio the engine is running at peak efficiency, and most of the time the vehicles got about 20-30 more horsepower, and the customers return claiming 2-5 mpg increases. Here's the problem with chips and programmers, so many people do it in their driveway and wonder why the lose mileage, and have minimal power increases. This is because if your not on a dyno to tune it right, you're just guessing. I have a SCT flashpaq on my '00 Harley F150, and my mileage is suffering because I have yet to properly dyno tune it. Oh, and on my programmer shift points only change if you actually program them to. I bumped the shift pressure up for firmer shifts from 1st to 2nd and 2nd to 3rd.

 

What about underdrive pulleys? Do they help or hurt?

 

Under drive pulleys:
This mod depends on the user and what he is looking for.
The mod came off the drag strip many years ago.
If your looking for the last lb/ft of torque it has it's value on the timing slip numbers.
On the street, the water pump, the fan, the alternator and power steering will all take a performance hit depending on what pulleys are changed.
That can bring with it cooling issues, A/C issues and charging issues at low speeds because everything is turning slower than design rpm.
And so it depends on what your willing to put up with and what pulleys are changed .
Basic difference is better throttle response and possibly a small amount of fuel mileage gain as long and you don't enjoy the added throttle response to often and negate any gains there might be.
Good luck.

 

Thanks. Ive been wondering about underdrive pulleys. I have a 98 4x4 f150 and i have been planning on underdrive pulleys, electric fans and a programmer/tune tuned by a shop on a full dyno. Trying to get the best power and mpg.