Holley Sniper EFI Woes (De Ja Vu) :(


Troy Torbett
Contributing Member
Yep, Here we go again! On the cruise to Shepardstown, WV last Saturday, my car began to randomly lose power and stammer between 1800 and 2000 RMP. It started after the traffic jam on Rt. 9. The problem became more frequent as we go closer to our destination. Even on the return home it just was not good. The problem wasn't just within the RMP range stated earlier. It was all RPM levels under load. Strangely, it idles good.

I haven't began to troubleshoot the problem. My thought is s*** here we go again. This is frustrating as hell. Anyway, I have started looking at the Holley website and forums for solutions. I will start simple items, such as check for loose injector connections (an apparent problem with the 1st gen Sniper EFIs). I really hope that it is not the fuel pump, which is new. I really dread taking out the tank and removing the pump to replace it. :tickedoff:

FYI, the general Sniper parts I have include:
1. Sniper EFI Part No. 550-51
2. Holley Sniper EFI Hyperspark Coil Part No. 556-152
3. Holley Sniper EFI Hyperspark Distributor (Ford small block - 260, 289, 302) Part No. 565-322
4. CD Box Part No. 556-151

My EFI set up does not have a fuel pressure gauge. I'm thinking of purchasing one for testing only and not leave in the engine bay permanently. Unless you think otherwise.
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I'm wondering if RFI/EMI is impacting your Sniper's electronic control unit. Here's a quick check you can do to rule out failing plug, coil, alternator, and other wires.

In a dark garage with the engine running, look for electrical arching and discharges. Use a long piece of wood to move the wires around while the engine is running to simulate wires bouncing about while driving. Try this with the engine at low and high engine temperatures.

Look over your wiring:
- Check that the coil is at least 6 inches from the Sniper's ECU
- Check that Sniper sensor wires aren't bundled with power wires
- Check that Sniper sensor wires and power wires aren't in close proximity and running parallel to each other
-- If possible, route Sniper sensor wires so they cross power wires at 90 degrees

RFI/EMI shielding options:
- Faraday tape
- Ferrite beads
- A little dielectric grease on spark plug/coil terminals
- A metal grounded shield in front of the EFI/ECU (between the ECU and coil)
- Some air cleaners act like a RMI/EMI antennae just above the EFI/ECU. Using a delrin stud in the air cleaner instead of a screw or bolt may act as an insulator

Good luck!
I saw a guy at Katie's awhile back with an FFR with Sniper EFI. He had made an RFI shield that was sandwiched under the carb unit and was bent upward in front. It was a work of art. I'll see if I can find the picture I took of it
I do have a RF shield with RF/EME sheet tape on the alum shield. It is somehow secured to the front of the EFI where the ECU is. The shield is positioned between the ECU and the distributor to alleviate the RF issue... or at least I hope so. I will take pics. The coil is mounted on the driver's side at the alum. "F" panel.
Look down your 4 throttle bodies when the car is idling. All 4 should be wet. I had the exact same symptoms in my Bronco. It turned out to be a bad injector, but 90% of the time it is the connection at the injector. Either way it is an easy fix. If that's the issue I can talk you through it and send pics.
Thanks Phil. I will look there. I did read and watch a video on this exact thing you mentioned.
This seems like an easy fix...if it is the cause of the problem. I hope this is the issue. I don't want to go down another rabbit hole trying to figure out what's wrong.
I saw that you sent it back to Holley. They told me that i had to send one back, but I already had mine disassembled. The injectors are available at Summit or Jegs and the repair takes 20 minutes. Thier customer service is aweful. Hopefully they will upgrade the injector connectors as well. Hopefully you will like it when you get it back. After the new injector and 2000 miles I love mine.
Phil thanks for bringing this back up. Update: I received it about a week and half ago and reinstalled it last weekend. There was no report with the packaging to indicate what was wrong with it, so I called them and they told me connectors for injectors 1 and 4 were loose. Everything else was good including the ECU. I was puzzled by this because I thought all the injector connections were good and I installed zip ties around the connectors to make sure they stay in place. I haven't run the car yet to see if anything has changed. If not, my last resort would be the O2 sensor.
UPDATE: I finally got the car out last weekend and it runs great! This time, I noticed fuel in all four bowls of the throttle body while the ignition is on and during idle. O0
I hope to build confidence in this heap as I drive it more and farther.
UPDATE: I finally got the car out last weekend and it runs great! This time, I noticed fuel in all four bowls of the throttle body while the ignition is on and during idle. O0
I hope to build confidence in this heap as I drive it more and farther.
That's great. Hopefully no more issues. I am having good luck with mine. It should get better as you drive it.