Grand Marquis Tuner
 

You MAY want to do the Tuning yourself, instead of relying on the parameters available from a "Store-Bought" tuner program.
You will need:
A LAPTOP computer that has Windows 10 installed.
Download "FORScan" (@forscan.app) into the laptop. It's FREE for a trial period. FORScan is a diagnostic app for FORD vehicles.
OBDLinkEX is a diagnostic scan tool that plugs into your OBD socket (under dash) and connects to your laptop's USB port. Instructions on the package are simple and easy-to-follow. Need help?? Go to "obdlink.com/support".
OBDLink EX will give out Dealership-level Ford/Lincoln/Mercury diagnostics with lightning-fast data transfers.
Comes with 3-Year Warranty. I got mine from A m a z o n.com -- about 50 clams.
Pre-loaded tunes !?? That's gonna be a tough gig, since there are so many variables on modern vehicles, including engine and transmission options, climate variables, and driving styles.
I don't know of any tuner programs that allow Speed Limiter removal -- it's NOT a good idea, since it's there for specific reasons determined by a flock of automotive engineers.
In stock form, your factory-tuned Grand Marquis will top out at 110 mph. If ya wanna go faster than that, get a different car.
The "stock" rear-end ratio is 2.73 -to- 1, which yields 2000 rpms. at 80 mph -- and 24 mpgs at that speed. A gear-ratio change to a "lower" (best for drag-racing) ratio will allow a quicker ET, but your gas mileage will SUFFER when you're NOT racing, which is most of the time.
Regardless -- a gear change to a 3.55-to-1 ratio requires a SPEEDOMETER GEAR change -- to a 21-tooth speedo gear. NO "reprogramming" of the computer is necessary.
There's an old saying around the Speed Shops -- "Speed costs money. How fast can you afford to go !??"
You have a 2-ton car there. It's a cruiser, not a racer. Set it up for cruising at higher speeds -- you'll have more success, and be happier when you're finished.
When all is said and done, the all-around best performance Bang-for-the-Buck modification is a Dual-Exhaust System, with an H-Pipe and REAL straight-through mufflers, such as the MAGNAFLOW Glasspax, that have no internal louvers or baffles of any kind. This system (2-inch diameter) yielded 22-24 horsepower over the factory single-pipe system, checked with G-Tech Pro.
If ya wanna spend too much money for too much noise, go with the popular Flowmasters.
Anyways, good luck with your tuning, and let us know how you make out.
https://cimg2.ibsrv.net/gimg/www.mer...4bb0ae04f0.jpg
Walker H-Pipe; MagnaFlow 2" Glasspax ; Walker Tailpipes -- Adds 22-24 Horsepower over stock (single) exhaust.