The guts of the "little black...
The guts of the "little black box" exposed. Like a marriage counselor, the Digispark interface module keeps the original ECM and the LT1 PCM on speaking terms.
Part of a Digispark installation involves programming the PCM for proper engine control. All systems come with a custom pre-programmed PCM to get the car running. The kit can be further expanded to include licensed TunerCat software, licensed Datamaster scanning software, and a diagnostic port-PC interface cable. Since the PROM that's hard-wired into the LT1 PCM is electronically erasable, all reprogramming operations can be accomplished by connecting a PC to the PCM through the interface cable, which plugs into the diagnostic port (also called ALDL, which stands for Assembly Line Diagnostic Link) that's connected to the LT1 PCM.
In addition to controlling engine functions, a PCM also has the capability of controlling an automatic transmission. With a 700R4, Digispark only controls torque converter lock-up. If a Digispark system is installed, a vehicle owner then has the option of replacing a 700R4 trans with a 4L60E. Although the latter is essentially an electronic version of the former, it offers the advantage of altering upshift and downsift shift points, shift firmness and torque converter lock-up to be altered by a few keystrokes and reprogramming the PCM, as opposed to making mechanical modifications to the transmission.
Although installation of a Digispark system isn't terribly difficult, it does require a 21st Century mentality that's comfortable with electronic equipment (like cell phones, personal computers and the like). As Burch puts it, "On a scale of 1 to 10 (most difficult), Digispark is probably about a 6 or 7. A Corvette owner who can competently replace a distributor and is skilled enough to read email should have no trouble with this kit. Use of a dyno will be necessary to obtain max power, but drivability tuning only requires the scanning software and a fairly level road where a steady speed can be maintained for 2 to 3 minutes. And if someone gets in trouble, help is only a phone call or email away."
Although the Digispark system was designed to simplify and expand tuning capabilities, it may also become a lifesaver for C4s. As replacement ECMs and PROMs continue to become more difficult to find, a Digispark system may become the best option available to keep L98 engines alive.
|Difficulty Index - 3 Wrenches|
|Anyone's Project: no tools required||1 Wrench|
|Beginner: basic tools||2 Wrenches|
|Experienced: special tools||3 Wrenches|
|Accomplished: special tools and outside help||4 Wrenches|
|Professionals Only: send this work out||5 Wrenches|
A complete Digispark C4 kit...
A complete Digispark C4 kit contains everything pictured here. If you'd prefer to source some of the components yourself, you'll need the parts shown below the black line.
The Digispark Test Control...
The Digispark Test Control Center--also known as the interior of Wes Burch's '91 convertible. In addition to the existing instruments, Burch installed an Innovate Wide Band system and a few other gauges. Fuzzy dice serve as an "analog" accelerometer.
Aside from the LT1 PCM, and...
Aside from the LT1 PCM, and the relocated original ECM, there isn't much evidence that engine control is being handled by a Digispark system.