Jeremy Formato Takes On Chip-Tuning A C4

Tuning today’s autos can be a very sophisticated array of tables and inputs and FasterProm’s Jeremy Formato is a seasoned veteran of getting the most out of an engine. He’s been on the forefront of tuning today’s cars, starting way back when they needed to burn the information to a “chip.” Much has changed since then, but Jeremy recently went head-to-head with one of these ancient ECUs for both sentimental and nostalgic reasons.

Jeremy’s dad, Jim Formato, was a legend in the Tampa, Florida area and started a business called FasterProms. He was noted as an experienced tuner of C4 Corvettes back in the 1990s and accomplished things that others deemed impossible. To prove his abilities, Jeremy’s dad built his own 1987 Corvette. He filled the block with 420 cubic-inches from a bored-and-stroked 400 small-block. He placed a hefty solid-roller camshaft in it, which tickled a set of Jesel rockers topside. He also installed an early version of what came to be known as a Mini-Ram intake with a mono-blade throttle body out front.

What once was an L98 has been replaced by the senior Formato with a 420-inch small-block wearing a high-revving Mini-Ram intake.

The Mini-Ram is a short-runner replacement for the long-tubed Tune-Port system that was originally fitted to an L98 engine. It is similar to an LT1 intake but you’ll note the distributor poking up through the rear, which definitely isn’t a Gen-II design. To control the radical engine, Jim upgraded the factory ECU with a unit from a 1990 Corvette to make use of the faster data transfer available with the newer computer.

Jeremy’s dad used the car as a calling-card, as well as a test-bed for new ideas. He even designed a special trap-door within the dash, so he could remove the EPROM and re-burn it with a reworked tune as he was perfecting the fuel and spark on his hot-rod. He would drive the car to the nearby track, cut 10-second quarter mile times and drive the car home. A herculean task back in the ‘90s!

Fuel and spark were addressed first. Fuel injectors were replaced and the old fuel was removed from the system once the external fuel pump was coerced back into operation.

Jeremy’s dad passed away and his C4 sat for many years as technology and other pressing issues moved on. Jeremy kept the family business going and is now a noted tuner of his own making, no doubt learning much from his father. He recently pulled his dad’s C4 from moth-balls and decided to get it running again. Jeremy’s dad would have likely used an LS engine for power today, but with the amount of nostalgia and memories attached to this particular car, Jeremy rightfully decided to keep it the way his dad designed it back then. It serves as a memory to him, and a lesson to those not familiar with what it took to tweak a tune back in the day.

For starters, tuning took more than simply plugging-in and a couple keystrokes. For most early C4 owners, a tune meant pulling the passenger’s seat, crawling under the dash to peer up behind it, and nestled between the firewall and the HVAC system were two small bolts. Remove them and a plastic brace dropped down and allowed a silver box to be wiggled down into view. I once asked then C5-Corvette Chief Engineer, Dave Hill who’s idea was it to put it there? He smiled and replied, “Not me!”

After doing that exercise, it’s easy to see why Jim Formato used that trap door to make frequent tweaks more survivable. The video is an accurate view of what tuning meant back in the day. Real-time changes were unheard of, and each change, no matter how small, meant removal of the EPROM to re-flash it with the new information. Many times, the ECU was simply left on the floor of the car until all tuning was completed.

Jeremy's dad fabricated this trap-door to access the EPROM without removing the ECU. Jeremy sorted through a stash of EPROMs to find one suitable to get the car running. A tuner would clear the program from the EPROM and then "burn" the new calibration to the chip, which is then inserted into the ECU.

There are prevalent pitfalls with any tuning session and this one has the added complication of time. A fuel system caked with stale fuel and the lack of real-time data meant that Jeremy was going to be flying through uncharted waters by the seat of his pants, much like his father did back in the day. In his words, this was, “Dinosaur stuff!”

After getting the external, aftermarket fuel pump working again and replacing the injectors with a newer 42Lb/hr set, the car was fired after many years. The first pull on the dyno is accurately described by Jeremy as “Pretty ugly”. The engine would go rich, then lean, and react accordingly with belching smoke or misfires.

Adjusting fuel pressure was more mechanical than programmable, thanks to an adjustable fuel pressure regulator (left). Fuel pressure could be adjusted by moving a screw in or out of the top of the pressure regulator.

The next step was bumping the fuel pressure with an adjustable fuel pressure regulator, another tuning tool used by many back in the day before frequency-modulated fuel systems. The tuning process back then was part electronic, part mechanical, and part voodoo. It rewarded those reserved individuals who were equally astute with both computers and wrenches.

Another nostalgic nod to C4-dom was an issue with the Electronic Spark Controller (ESC) which was externally mounted on this ’87 Corvette. Now, spark control in every situation is controlled internally by the ECU and is infinitely adjustable in range from poor performance to mushroom-cloud advanced. Back then, a little black box was mounted on the firewall and wired into the harness to control the spark advance. Some quick thinking on Jeremy’s part put the necessary spark advance into the ignition, and horsepower jumped from 289 to 407 horsepower.

As the fuel and spark tables were tweaked even further, horsepower continued to climb. Ultimately, the final round of tuning garnered 471 rear-wheel horsepower, using 1990’s technology. THAT was super-car territory back in the day. Remember, the highly-esteemed ZR1s only made 405 horsepower to the crank. All in all, the video checks all the boxes for the typical car guy – Jeremy shares stories about his dad, it shows some of the trials that faced tuners back then, and it has a very cool car as the main subject. Astute eyes will also note that the shenanigans carry into the wee hours of morning before the crew calls it quits.

Several chips later, Jeremy and friend Cleetus McFarland take the C4 for a spin. Of course, smoke ensues!

Jeremy has posted several other videos, both before and after this one, but we felt that this one would make a great introduction to this C4 and its continuing journey for more power. Feel free to watch some of Jeremy’s other videos to see how the project started and also, how it did at the track. Be warned though, you may find yourself binge-watching all about a C4 Corvette. But don’t worry, we won’t tell.

About the author

Andy Bolig

Andy has been intrigued by mechanical things all of his life and enjoys tinkering with cars of all makes and ages. Finding value in style points, he can appreciate cars of all power and performance levels. Andy is an avid railfan and gets his “high” by flying radio-controlled model airplanes when time permits. He keeps his feet firmly grounded by working on his two street rods and his supercharged C4 Corvette. Whether planes, trains, motorcycles, or automobiles, Andy has immersed himself in a world driven by internal combustion.
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