Holley recommends that you follow certain recommendations when installing the ECUs for their Electronic Fuel Injection systems. All images from screen captures.
Just like with your home computer, proper installation is vital to ensuring you get consistent and reliable service for the life of your Holley ECU. Holley says that properly installing your ECU means mounting it and hooking it up to the vehicle’s electrical system correctly. Let’s take a look at what Holley recommends.
Mount the ECU Correctly to Ensure Long Life and Reliability
Left: Find a suitable location for the ECU that isn’t going to bind the connectors or subject the ECU to being splashed with liquids for prolonged periods. Center: Use painter’s tape to mark the mounting holes for drilling. Right: Use the nylon insulators and supplied stainless hardware to mount the ECU.
The main thing to remember when choosing a mounting location is to make sure you don’t choose a location that will have the ECU immersed in water. After that, you need to make sure that it’s securely mounted to something sturdy, like the bulkhead or inner fender. Finally, make sure that you fully isolate the body from the ground using the nylon washers and isolators supplied.
Power and Ground Directly to the Battery
These two images show the wrong way (Left) and the right way (Right) to hook up your Holley EFI ECU - directly to the battery.
I know many of you out there use distribution blocks and lugs when hooking up electronic components in your car. That’s fine with things like AC compressor clutches, nitrous solenoids, line locks, trans brakes, and the like. However, it isn’t OK when you’re installing sensitive digital electronic components like an ECU.
Watch Out for Transient Voltage
Don’t use a “bolt you found” to hook up the power connections if you’ve got a side-post battery. Get these side post extensions to do the job correctly.
All these other components can cause large transient voltage spikes, and if you don’t have your ECU connected directly to the battery, the spikes will enter the ECU and damage or destroy it when they occur. The battery acts like a buffer, absorbing these transients before they have a chance to damage the ECU.
More Wiring Considerations
Always use a crimp tool when crimping solderless connectors. Also, always align the connector in the crimp tool with the split in the connector toward the saddle in the tool, not toward the nipple.
Some of us may want to mount our Holley ECU inside the passenger compartment. That’s fine; it comes with more than enough wiring length to accommodate this. Just make sure of the following:
• Be careful when drilling through the bulkhead for the wiring harness to make sure you don’t drill into something like your heater core
• Make sure you deburr every hole that you drill before running wires through it
• Use some sort of grommet to protect the wiring and make sure you use the right size grommet. In other words, don’t cut a larger grommet down to fit.
Keep it Smooth
Always use the proper size grommets when running wires through penetrations in metal. Also, be sure to deburr the holes before installing the grommets.
Another important consideration is the use of the correct tool for the job. Most of us will grab whatever’s most handy to turn a nut or bolt. We’ll grab whatever “squeeze tool” is closest at hand when crimping solderless connectors. This is wrong and just asking for a weak connection. Use a wire crimper for connectors and make sure the split in the connector sits in the saddle of the crimper. Line the split in the connector up with the tip of crimper and you’re just asking for a failed connection.
Holley’s ECUs are Tunable for Street and Strip
With a little practice, you can use the Holley EFI ECU to control a variety of outputs such as line locks, trans locks, nitrous solenoids and more.
An EFI ECU (Electronic Fuel Injection Engine Control Unit) uses a variety of sensors to control the flow of fuel into your engine. These sensors can include MAP/MAF sensors and oxygen sensors. When you make changes to your engine’s fuel delivery system, the stock ECU will take a few minutes to adjust to the new engine parameters. A Holley EFI ECU will do the same thing. Unlike a stock ECU, the ECU that comes with Holley’s newest EFI systems can be tuned using a handheld controller.
You Can Program Preset Ratios
There’s even a function in the control software that allows you to preset a stoichiometric air-fuel ratio so the computer will “learn” the parameters required to maintain that ratio.
This means you can customize your engine’s tune without a computer or scantool. Simply grab the handheld touchscreen remote, bring up the screen you want and modify the settings or pick from a number of presets. If you’re running an oxidizer like nitrous, the touchscreen control lets you fine tune the engine to get optimum performance out of it. The Terminator and Dominator systems also allow you to have the computer automatically control your nitrous system. This is something a stock computer can’t do.
You can even use the Holley ECU to gain finer control over your GM transmission than the stock ECU gives.
A stock ECU will require a computer with the right software and connection to the car’s diagnostic port in order to do this; plus, you’ll have to know how to use the software to get the most out of your strip burner’s engine.
Mike's love of cars began in the early 1970's when his father started taking him to his Chevron service station. He's done pretty much everything in the automotive aftermarket from gas station island attendant, parts counter, mechanic, and new and used sales. Mike also has experience in the amateur ranks of many of racing's sanctioning bodies.
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