When the Sniper 2 EFI system broke cover last summer, it was an evolution of Holley’s popular throttle body electronic fuel injection conversion kits—offering plenty of refinement and enhancements over the previous Sniper 1.

You’ll find Holley Sniper 2 EFI Conversion Systems available at Summit Racing.

But the debut of Sniper 2 also raised plenty of questions from folks mulling an EFI conversion, not only about the differences between it and the Sniper 1 system, but also about what else you’ll need to consider for a successful install.

So to get some clarity on the topic of EFI retrofits, we sat down with Colin Kinser, a tech expert and EFI product manager over at Holley Sniper, for an episode of the OnAllCylinders podcast.

You can listen to the whole episode here or at the OnAllCylinders podcast section, and we’ve pulled 10 excerpts from the interview that you can read below.


1. Tell Us About Holley’s History with Electronic Fuel Injection.

“Prior to my tenure at Holley, we had the Commander 950 and the Pro-Jection 2D/4D products that were both TBI and multi-port systems. Those TBI systems were based on some OEM technology that we acquired back in the 1980s.

“When I started in Holley’s tech department, we had just released the Terminator throttle body EFI system—that was really, like, the first in the current wave of EFI systems that we carry now.

“From that, we evolved into Sniper 1, which was a huge success. With the Sniper 2 system, we have learned the pain points consumers have had while installing the system and updated and improved upon them.”

2. So, You’re Learning from Consumers About Your EFI Kits?

“We’ll go to trade shows and events to interact with the customers—but I’ll go as far as to go under someone’s car and diagnose a problem in real time. And what that offers us, is the feedback and insight as to what’s actually happening in the field.

“It might be ignition installation, wiring, condensation on the O2 sensor, transmission kickdown, throttle linkage—just whatever. All that information is gleaned from trackside experience or being on the tech service lines.

“We have the Holley Sniper EFI Owners & Tech Facebook Group too. We might not post in there every day—but you can guarantee one of us has read every single one of those posts, good or bad, to glean information.”

3. Talk About Some of the Enhancements of the Sniper 2 Over the Sniper 1.

“From the ground up, the Sniper 2 was redesigned when you compare it to the Sniper 1—other than being a four-barrel throttle body with a 4150 flange.

“We moved the ECU to the side and redesigned it from the board up, all new hardware, new firmware, new drivers, new everything.

“The harness has been redesigned, along with the injector clips themselves, we have a positive-lock injector clip that’s on there now. The throttle position sensor has no been incorporated into the ECU, and it’s a non-contact TPS that’ll be good for our lifetimes.

“We’ve improved the throttle lever—we noticed people were having kickdown issues, geometry issues. So, we went to a 80457 design, which is the most popular carburetor Holley’s sold in the last 10 years.

“We added a Ford C4 kickdown, which was a big pain point for the Blue Oval folks—including me, I’m a Fox Body guy.”

4. Why Did You Relocate the Motherboard on the Throttle Body?

“So on a Sniper 1, the ECU was front and center. But on some Ford applications, your distributor’s in the front—so you’re around a lot of ‘noise.’ Moving the ECU to the side can boast some benefits, in getting the electronics as far away as you can from electrical noise.”

You may enjoy this article: What is EMI & RFI? And How Can You Stop Electric & Ignition Interference?

5. Should You Replace/Upgrade Other System Parts During an EFI Swap?

“In my experience, buy a new fuel tank. Old tanks are just notorious for having bad particulate in them—gum, rust, whatever—and as soon as that gets to an injector, you’re going to have a bad time.

“So a new fuel tank is always a little bit of insurance. And an in-tank pump is almost always going to run cooler and quieter.

“As far as your ignition system goes, a Hyperspark distributor has a Hall effect-based ignition input, so it removes the magnetic part of the distributor and it allows the Sniper ECU to have full timing control. You can still do timing control with a magnetic distributor, but a Hall Effect one’s just cleaner, the resolution’s higher, and the signal’s better.”

6. Do You Recommend a Return or Returnless Fuel System for EFI?

“I almost always recommend a return-style fuel system. It keeps your fuel pump happy and cool, and circulating fuel is always the best.

“Returnless is great for lower horsepower applications. We don’t usually recommend a dead-headed or returnless fuel system unless you’ve got less than, like, 350 to 400 horsepower.

“One thing that you will see in a returnless system, is that there’s some more noise in the system, depending on where the returnless regulator is mounted—sometimes it’s in the tank, sometimes it’s on the frame rail.”

7. What Advice Would You Give Someone Undertaking an EFI Swap?

“The fuel system is your backbone—making sure your pickups are clean, making sure your fuel filters correct, making sure your filters are clean.

I would recommend upgrading the fuel system as much as possible, for both longevity and upgradability later on in the future.

“Go a little overkill, you’re never going to regret it.”

8. What Are the Biggest Challenges to an EFI Swap?

“The number one thing is a switched 12 volt signal to the product. So, get a good multimeter, and make sure your switched 12 volt is ‘hot’ when the key is on. But it also must have good amperage—sometimes a low amp 12 volt signal will cause a lot of problems. So, validate that you’ve got a good source. We have a good 12 volt tutorial in our installation videos.

“From there, it’s exhaust sensor placement. Make sure you have a nice place, after the exhaust merge, that is not going to leak.

“Once you have that, it’s the fuel system—as we’ve already talked about.”

9. Explain How the “Self Learning” Feature In Your EFI System Works.

“You run through the wizard in the handheld that comes with the Sniper 2 and build a calibration.

“It’ll ask you engine cubic inch, timing at wide-open throttle, timing at idle, target air/fuel ratio, and it’s going to build a base calibration for your engine. Now, if your engine’s got normal vacuum—not a race engine, race cam—normally that base calibration is actually pretty spot-on.

“For folks with a more aggressive cam, you can go in the tuning software and add or remove fuel, add or remove timing, if you have timing control, and fine-tune the system.

“In ‘Close Loop and Learn’ mode, the handheld will show you compensation percentages that are normally in, say, the three to 12 percent range. If you find on your first drive that you have a reading that’s, like, 60 to 70 percent out, then you probably have an issue—fuel pressure, exhaust leak—something is causing the egregious number. That’s a great time to stop, see what’s going on, re-run the wizard, and go out for another drive.”

10. Any Tips for “Self-Learning” on That First Drive?

“The ECU doesn’t go into ‘Learn’ mode until your coolant’s over 160 degrees. So first things first, you need to make sure the coolant temp is reading properly on the handheld—sometimes you’ll have it in a spot that’s cold, or sometimes you forget to hook it up.

“So once you get it up to 160, and you don’t have any exhaust leaks—which can result in false lean or false rich readings—and you don’t have any fuel leaks, just go out for a leisurely cruise around the neighborhood.

“Personally, I do one to two laps around the neighborhood, then I find a nice, safe environment to give it wide-open throttle.

“It’s going to learn your fuel demands as fast as the engine is turning. So find your rev limiter…[laughing]…and let’s get there. ”


Hear this interview in its entirety in the OnAllCylinders Podcast series, available wherever you get your favorite podcasts.

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