Here's a copy of Ford's warranty policy
PonyX2 , here's that article, concerning the warranty policy, I submitted a long time ago. For those of you, who may be interested.. I found this thread on the The Mustang Source Forum, that goes into furthur detail about the factory warranty issues.. its an article written by Joe Bradley, who is manager of Ford's Warranty Analysis Department..I'll have to copy and paste the entire interview, due to my browser won't allow me to, include a hyperlink.. sorry for such the long post..
Modifying Warranty Awareness Know that when you modify your vehicle, you may also be affecting warranty coverage
Editor's Note:
A recent article in the SVT Enthusiast discussed the pros and cons of changing engine drive pulleys to help enhance power and performance. The story noted that one of the drawbacks to such an aftermarket modification is the possible effect it would have on the owner's New Vehicle Limited Warranty. When SVT's own Tom Scarpello read the story, he felt that the whole vehicle modification vs. warranty issue is one that deserves a little more than a cursory explanation, especially to performance-savvy SVT vehicle owners. So he asked Joe Bradley, the Manager of Ford's Warranty Analysis department, to add a little perspective on how certain vehicle modifications can affect the service life of some factory parts or systems, and how that may subsequently affect the factory vehicle warranty. The following is Joe's report.
By Joe Bradley
As you might expect from the company that formed SVT, the Ford Motor Company has many employees who are true performance enthusiasts -- folks who love and care for their personal high-performance vehicles as much as or more than the next guy or gal. Many of us, in fact, are true "weekend warriors" who can be found at the local drag strip or road course on Saturdays and Sundays, and tinkering under the hood during weekday evenings getting ready for the next event. As automotive enthusiasts, we certainly can appreciate performance machinery.
That said, as Ford employees we all want to do the right thing for our customers as well as for the Ford Motor Company. That is precisely why it is important to have a concise, easy-to-understand policy with regard to Ford warranty administration. For vehicles that are not modified, the Ford warranty policy is clear – the company backs its products within the guidelines of the new vehicle limited warranty, which is designed to protect the customer from defects in factory workmanship and/or material.
However, in the case of vehicles that have been modified, one needs to understand that the modifications may affect warranty coverage. This is simply because any damage or failure of new vehicle components or systems that was caused by modifications to the vehicle are not defects in "factory supplied" workmanship or material.
To illustrate this point, let's consider a small sample of vehicle modifications and see how they might affect factory components or systems: When it comes to changing the factory engine drive pulleys, there are some powertrain system and component concerns that deserve consideration. One would be any electrical and/or charging system problems that arise because of reduced alternator operating speed caused by the installation of underdrive pulleys. After all, the performance and serviceability of many system components are based on certain design parameters that include operating speed. The same goes for problems stemming from higher cooling system temperatures because of reduced water pump flow caused by the installation of underdrive pulleys. Increased underhood temperatures caused by owner-induced changes to a factory design-specification part can have a detrimental effect on any number of powertrain components or systems – some that may have long-range implications. And things can get even more serious when supercharger pulley changes are made, including head gasket leaks and piston and connecting rod failures. Also possible is piston damage due to detonation from improper air/fuel and timing modifications.
The installation of any non-factory forced induction system can also cause problems. Base engines modified with aftermarket superchargers, turbochargers or nitrous oxide injection systems may indeed bring about some power gains, but they can cause piston, connecting rod and/or crankshaft failures as well.
Other parts of a vehicle's factory-spec drivetrain are also susceptible to damage when engine torque and horsepower is increased. Performance chips or other power-enhancing devices increase torque loads on the driveline and can force failure of the transmission and/or rear axle. The latter problem can be especially true when owners switch to wider tires or racing slicks in an effort to increase traction. Even non "go-fast" aftermarket accessories such as remote starters, alarms, supplementary gauges and audio equipment can cause electrical system service problems if they are installed incorrectly or have improper connections.
When it comes to fairly evaluating the possibility of a warranty denial, there's one simple rule of thumb to follow: Although the installation of non-Ford parts and aftermarket modifications, by themselves, will not void the Ford New Vehicle Limited Warranty, failures that result from these parts and/or modifications may result in a denial of warranty coverage for such failures or damage.
The bottom line is, Ford Motor Company wants each of its owners to enjoy their product to the fullest extent – and that includes performance vehicles. But dealer service technicians have seen, and continue to see, that modifications may cause the original design to fail. The addition of aftermarket parts is a risk that each and every vehicle owner must evaluate for themselves. All that's needed is a reasonable dose of common sense. When and if you modify your vehicle, please consider whether the modification may cause another component to fail – and if it does, recognize that warranty coverage for that failure or damage will likely be denied.
Here is the way I see it.
1) From a strictly legal stand point it "can" void your warrantee on most drivetrain components.
2) Ford has laywers on staff, so in a legal exquisite feeling release of liquid waste product match you are going to lose. Legal or not, fair or not, the legal clout Ford could bring to bear will put the burden of proof on you.
3) The Magnasun-Moss act ( the one every preformance adder quotes) was originally written to prevent manufactures from voiding the warrantee on your car if you chose to use NON-Manufactures consumable parts like: Oil, Filters, Brakes, shocks, etc... It was NEVER written or intended to cover parts that are installed primarly to increass hp and torque. I doubt that the law would hold up in court when the components were installed mainly to add HP.
4) Look at it this way:
Lets say you break somthing in the Transmission after installing the tune. The Ford lawyer asks: Does this device add HP and Torque to the engine? To avoid purjury you answer "Yes"... You just lost the case....
5) However, if you have a good dealer who does preformance mods you probably have nothing to worry about. A Tune is not all that major of a modification and unless it is done incorrectly, I doubt any resonable person would think it would be responsible for breaking somthing...
Now, if you sho up at the dealer with DOT Drag radials and numers written on the windows,..... well... You are on your own....
heck, not only did I still have numbers on the window, I still had my helmet in the back seat! LOL!
Each dealership is different... The dealership I go to is amazingly cool with my mods... Like I said the service writer goes to get the car's milage and says "Why do you have a helmet in your car" wink.. wink..
The dealership went on to replace my TPS for free even though my Zex kit was still spliced into the TPS wire! But on the other hand one guy posted that his dealership gave him a hard time about the popping front noise... tried to blame it on his aftermarket muffler! LOL!
I was at a car show this summer.. Got to talking to a guy who worked for Chrysler as a Factory Rep... his sole job was to look at warranty claims... We were talking about me using Nitrous... He had seen numerous cars that had blown motors that he knew were the result of a power adder that had since been removed but said since there was no way he could actually prove that it was the cause the failure so they fixed it...
I agree though that tuner is a pretty safe bet....Notice that he basically said that Ford follows low (Magnuson-Moss Act) in regard to warranty process. If you did something that broke the car, and they can prove it, you are on your own. As you should be. If they can't prove it, or you didn't do anything, it is covered.
Also, the Magnuson-Moss Act is a WARRANTY act. Not just a "consumables" act. There is a lot in there regarding consumables (mainly because dealers were doing the "if you don't have use change the oil at xyz intervals with our oil/filter/etc, then your warranty is void!" kind of crap), but it also goes into general warranty protection. Including modifications.
And yes, Ford DOES have a lot of lawyers. There is also provisions in the act that force things to arbitration instead of the courts too.
I have had the service department scrupulously search to find the tune on our car and they cannot find it with ANY of the 3 types of scanners they use to update the computer or reflash with.
As in every time this issue comes up we find again that the results are highly subjective to the dealership at which you service your vehicle and at what lengths if any that they are willing to help you when it is or isn't a FORD problem. As scrming has posted we have the same luck with the dealer we use, they always are there to help. But 9 miles away at another dealer they would laugh and say "We have seen your wife tear the crap out of that car at the dragstrip, no way will we replace anything unless it is a recall or TSB. Even with that you will only get one chance."
Both dealers know we race and spray but one is proud to claim that they sold us the car and do warranty work. This isn't to say that if we spit parts out of the oil pan that they would help me get a new engine but they might chance it, and if the Ford inspector showed up the worst case scenario I would have to pay them for what they have already done. Fair gamble IMO.
Also, I have no problem nor would I expect, my dealer to cover for damages, that were directly responsible by for ie an aftermarket blower or something like that..However, when it comes to just installing an aftermaket product, It is completely, illegal for any dealership, to void a factory warranty, and in this case, if I had to take my dealership to court..I can guarantee you, that I will not lose and here's why..I'll have both field service engineer's on my side, and that you can take to the bank..
and goes on to say cellular phones. I said WTF? But Gale Banks said my truck was covered, ....no way Jose. You are right that the law was designed for standard replacement parts, but us dumbass hotrodders like me take it too far. I mainly replied first off so people would know there are consequences. In all honesty, a little tweaking DOES help our new vehicles run the way they should and I am all for it. Like most other things, if done in moderation, no harm, no foul. So, I will put my flame suit on now and be quiet. 
