Click for Coverage
Due to the EU’s Global Data Protection Regulation, our website is currently unavailable to visitors from most European countries. We apologize for this inconvenience and encourage you to visit for the latest on new cars, car reviews and news, concept cars and auto show coverage, awards and much more.MOTORTREND.COM
  • JP Magazine
  • Dirt Sports + Off-Road
  • 4-Wheel & Off-Road
  • Four Wheeler

Self-Learning Fuel Injection - Holley Avenger TBI EFI Kit

Posted in How To on January 1, 2012
Share this
Photographers: Jerrod Jones

My ’72 Chevy project started way back in 1994. I’ve cut, chopped, fabricated, bolted, screwed, wired, and plumbed most everything myself while restoring and re-engineering my 4x4 pickup. One thing that has always stayed the same was some form of a naturally-aspirated carburetor on all of my engines.

In fact, I took the factory fuel-injection system off of the Vortec big-block Chevy I am currently running and bolted an intake manifold and 750-cfm carb on before throwing it in my truck. But, as most of you know, wheelin’ with a carburetor has its challenges. Some people have it worse than others, but in my case, I don’t think it could have been much worse. Not only did my motor sputter out or just not run on off-camber angles, but it would simply shut itself down if I went over any quick bumps off-road. I couldn’t even pop over a speed bump at the grocery store faster than 2 mph or I’d find myself cranking the thing over with my foot to the floor trying to start my flooded-out motor! After years of the same old BS, I finally decided to make the change.

I knew that fuel injection was the answer that would solve all of the issues I was having. My major hang up with retrofitting fuel injection, aside from the additional cost, has always been my fear of dealing with all of the electrical and computer hassles I thought would be associated with the swap. And I didn’t have a dyno to tune the truck on so I’d have to find a shop that could program the fuel injection as well. As it turns out, I was pleasantly surprised to find out that new self-learning EFI kits took a lot of the headches out of a retrofit.

When I started looking into various ways of fuel injecting my big-block, I stumbled across Holley’s self-learning Avenger EFI 4BBL TBI System. According to their instructions, this system included everything I would need to convert my carburetor over to a throttle body fuel injection system, and it claimed to be easy to install for anyone that could work their way around a tool box. They even offer it in three separate kits for engines ranging in horsepower from 400 hp to 600 hp. This sounded good to me. I am pretty decent at wrenching on just about anything on my rig, but wiring and computer stuff is definitely not my favorite subject.

My new Holley Avenger kit showed up and I couldn’t wait to dig into the box. As I laid out all of the components and briefly read through the detailed instructions, I realized how simple this install was going to be.

01. The kit comes complete with everything you’ll need except the tools and the fuel line you’ll need to plumb the system. It includes two different sets of instructions to guide you through the entire process of installing the kit. The first of the two is the hardware installation instructions. This carefully explains what additional items you will need to install the system, how to properly remove your existing fuel system, the tools you will need to complete the install, and step by step guidelines on installing each component. The second set of instructions deals with the initial start up after everything is properly installed and tuning the system once you are up and running.

02. A couple things stood out to me, like the fact that I needed to address my existing fuel tank. The Holley Avenger kit comes complete with the fuel pump, filters and everything you need except the fuel line itself to plumb your fuel system. The pump supplies fuel to the throttle body at high pressure, and the built in regulator returns fuel through a separate line back to the fuel tank. This requires a fuel tank with a return in it or you have to modify your tank to add one. My old ’72 did not have a return back to the tank so I decided to build my own tank and mount it behind the rear axle between the frame rails instead of modifying the existing one sitting behind my seat. Once I had it designed, I picked up aluminum plate from Industrial Metal Supply for my new 30-gallon tank and began to cut and tack-weld the shape together.

03. I also took the time to design a cage to hold the 30-gallon aluminum tank. It bolts in directly in back of the 14-Bolt axle, out of the way of any suspension components.

It may seem like a lot more work to add onto an EFI system, but I plan on keeping this truck forever and it made sense to do the entire fuel system right the first time around.

04. Genright Offroad builds some of the best off-road gas tanks and helped me out with all the components I needed to complete my build. Bill Roncallo of BGR Welding was called upon to lay down some of his “sweet joy” (as we call it) and TIG-welded the whole tank together for me. As usual, the completed tank looked like jewelry when he was finished!

05. The EFI system is controlled by a computer, or ECU, that controls the fuel delivery through a throttle body that bolts directly to your manifold in place of your old carburetor. The ECU relies on a number of sensors that must be installed on the motor and exhaust system to help it maintain optimum fuel delivery to the motor. It constantly analyzes and adjusts fuel delivery at different RPM levels, elevation, ambient air temperature and pressure, vacuum, and engine temperature. At first, when reading about all these parameters in the instructions, I was a bit overwhelmed, but after reading through it a few more times, it became clear to me how simple it really was.

PhotosView Slideshow

06. I noticed (when reading through the instructions in the ignition/engine speed input section) that there are several different ways that the ECU can be wired to pick up the engine speed signal. This is the most important signal for the ECU. It can easily be set up to work with any style ignition system, such as an older points style distributor or my standard GM large-cap HEI. But, if I run an MSD 8366 Pro Billet distributor or a newer ‘80s GM small-cap HEI distributor, the ECU would also be able to control the ignition timing advance in addition to the fuel delivery! I had to do it.

07. The supplied throttle body is a Holley four-barrel unit that would easily inject enough fuel to amply supply my big-block Chevy. It bolted onto my existing intake manifold just like the old carburetor did.

PhotosView Slideshow

08. After carefully installing all of the hard components such as the throttle body, the manifold air pressure sensor (MAP), coolant temperature sensor (CTS), manifold air temperature sensor (MAT), and the wide band oxygen sensor (WBO2), it was time to run the electrical.

09. The wire harness provided with the kit literally laid out and plugged directly into the sensors. I drilled a hole through the firewall and routed the harness up to the ECU that I mounted under the dash. The most important thing they stress is ensuring “clean and uninterrupted” power and ground connections. When I was finished installing everything, I went back through and tidied up any loose wires and secured the harness. Then I checked and double checked everything before it was ready to fire up.

10. Now that everything was installed, it was time to transfer to the second set of instructions. These instructions deal with the ECU setup and tuning using the simple handheld control. Before the first start up of the engine, the handheld controller prompts you through the initial calibration steps needed to set up the ECU to best control your particular engine. It uses basic information such as engine displacement, camshaft specs, and type of distributor to create a basic calibration that will accurately run the motor.

11. I cranked it over and it fired up and idled flawlessly right away. The next thing I needed to do was sync the timing to the ECU. Using the handheld and revving the motor up to 2,000 rpm, I had a buddy with a timing light turn the distributor until the readout on the timing light matched what was showing on the handheld. Now all I needed to do was drive it to tune it!

12. One of the best features of the Holley Avenger TBI EFI Kit is its ability to self learn and self tune! And the best way for it to do this is to drive the truck under as many operating conditions as possible. The only time the system is not self learning is when the engine is below 160 degrees Fahrenheit, when the engine sees quick accelerator pedal movement, certain times when the accelerator pedal is lifted and the truck is coasting, or when the self-learn feature is manually disabled by the user. As I drove my truck with the new Avenger kit for the first time, I instantly felt a difference from my old carburetor. The motor ran very crisp and even more responsive and it seemed to have lost the hesitation it had right off the line and at low rpm through 2nd gear. These improvements were great, but I couldn’t wait to get this thing in the dirt and see how it ran up and down some steep hills! The next day we headed up to the local off-road park and I couldn’t get the motor to stall out on me in any position. With better throttle response, more power, better fuel economy, and reduced emissions, I really can't have any complaints about anything. I'd put this Holley self-learning system on any V-8.


Industrial Metal Supply
Irvine, CA 92606
Gen Right
Simi Valley, CA 93063

Connect With Us

Newsletter Sign Up

Subscribe to the Magazine

Browse Articles By Vehicle

See Results