VERY good questions!!!

 

I'm new here so if this has been ask, forgive me.

I've read a lot of this thread but not all.

A few days ago I picked up my New F-150 Platinum w/6.2L Engine.

I discovered that Ford electronically restricts the speed of this vehicle to about 99 MPH yet they put tires on it that are rated for 118 MPH. Doesn't make sense to me. Any body know why they do this? Are there any Performance Chips or programers that can remove the speed limit? Would doing so VOID the Warranty?

Love the Truck and Engine but the speed restriction is a thorn in my side.

 

Okay I'll bite...

Sounds like you should have bought a Mustang.

 

While chipping the motor might get you in warrenty hot water, hitting the top of the engine on the drivers side with a hammer will remove the speed restriction without voiding the warrenty.

 

 

Here's about the only "technical" answer you're going to get to your questions:

The speed limiter has more to do with the driveshaft ballooning and/or going out of balance than the rating of the tires. Been there done that with my '96 t-bird.

A tuner will remove that speed limiter, but you have to decide if it's in your own best interests to do that. For more about the 6.2L forum, scroll down the forum list and visit the "6.2L Boss" forum

 

99mph speed limiter? wtf? Thats the lowest speed limiter I have ever heard of. I don't think the speed limiter is for the driveshaft, if it is that is super **** poor engineering.

 

My Superduty is limited to 95. My '96 t-bird (and '97 Cougar) was 106.

 

94mph is 80% of the 118mph speed rating of the tires.
I'll bet it's actually 94 mph that the vehicle is actually shutting off at, not 99.
Either way,the limiter is there for a reason.
Flash the PCM=voided powertrain warranty since you have tampered with the operation control system.
JL

 

Over 100 limiters are normal. But in the 90's now?

 

"Now" ? My Superduty is 10 years old. I believe that limiter was there in the '99 SD as well...

And before anyone asks, yes, I've hit that limiter once or twice

 

10 years is fairly new in modern vehicles. At least to me.

 

Since the infamous Explorer Tire issue, one of Ford's product development requirements is a 20mph "buffer" between the speed the vehicle is capable of, and the speed the tires are rated for.

This is one of the ways in which they attempt to combat d-laminating, and the low speed rating on the Firestone tires fitted to the Explorer was considered one of the contributing factors in causing them to blow out.

F-450's fitted with 19.5" wheels I believe are rated to 92? (or something like that)

Removing the speed limiter will not void your warranty unless excessive speed was determined to be the cause of the failure. i.e. if your driveshaft yokes fail, they may not pay up, but if the air-con stops working they have to.

 

The F450's with the 19.5" wheels were limited to 84 mph. Many, many pissed off owners over that one. But, they chose the vehicle, so..I guess they were accepting of it when they bought it.
Reflashing the PCM will void the powertrain warranty. Other ancillary systems can be voided as well since operating the engine or trans outside of the tested and programmed parameters will put those items outside of their design spec. A/C compressor, power steering pump, alternator, etc, etc, etc....if anyone here honestly believes that the Magnuson-Moss Act will protect them in this situation, they have a RUDE awakening coming.
JL

 

I took out the bushing in the extension housing on the 4R70W in my '96 t-bird, pushing around 135MPH or so. The driveshaft ballooned and/or went out of balance at that RPM.