Holley Sniper 12v Source Question

Wes

Wes

Well-Known Member
Joined
Oct 14, 2007
Location
Ridgeway, SC
1969 Fairlane
428ci

My brother had a guy install a Holley Sniper EFI. Ran OK for a bit, but it shuts off at random because of a drop in voltage. I’ve read they’re super sensitive, and will shut off if it drops below 12v. At the moment it’s powered full time from the battery with the startup wire (pink) tied into the ignition as the directions call for. Problem is, the voltage drops on the ignition wire on startup thus getting a no start. It has a 140 amp alternator, the battery is good, everything is charging. I know a handful of you have installed these. What 12v source are you hooked to that doesn’t drop on startup? I suggested straight to the battery with a toggle switch and relay, but he wants to keep it clean on the dash. Thanks in advance

(The bottom paragraph in gray is our issue)

IMG_0881.png

IMG_0880.png
 
I run all my 12 volt ignition sources off of a fuse block powered by a 60/80 amp relay. Power straight from the battery just use the car wire to operate the relay. Basically bypassing any old wiring for true voltage. There is also another chassis ground or should be. Not just the one to the battery
 
Noel said:
I run all my 12 volt ignition sources off of a fuse block powered by a 60/80 amp relay. Power straight from the battery just use the car wire to operate the relay. Basically bypassing any old wiring for true voltage. There is also another chassis ground or should be. Not just the one to the battery
Click to expand...
That same block powers up my Holley, trans side of the Holley, alternator field, and my gauges. Also have my fan on it for it to run with the switch on.
 
Noel said:
I run all my 12 volt ignition sources off of a fuse block powered by a 60/80 amp relay. Power straight from the battery just use the car wire to operate the relay. Basically bypassing any old wiring for true voltage. There is also another chassis ground or should be. Not just the one to the battery
Click to expand...
I’ll check for that chassis ground
 
WTF kind of automotive EFI system cant handle brownouts below 12V during cranking? thats nuts! do you have an oscilloscope? you can scope the voltage at the module during cranking and see what it actually drops to.
 
go directly to the ignition switch. one of the high current wires there will stay 12v during crank. if it is dropping voltage you are on the accessory circuit
 
What @jeepn-jason said.

And make sure the battery is fully charged. Any variance in voltage with the sniper and it throws fits.

Also, just to beat @Bebop to the punch. It is marketed as self tuning but still needs to be tuned by a professional and all the maps dialed in for it to truly work right.
 
It’s parked at my dads about an hour away. I’ll dive on it next week when I have some free time and report back.
 
CarolinaHD said:
Tell your brother you know how to fix it but he's gonna have to help deliver a concrete mixer first.
It'll at least solve one problem.
Click to expand...
Be nice. He’s knee deep in wheat straw right now, and having him drive an hour might as well be cross country
 
Last edited:
Second on the starter. My TDI gave me fits over that one.
If still failing, perhaps double up on the battery (jumper to another battery), thereby giving double the amperage.
If that works, still could be any of the items above (wiring/ground, battery not having enough cranking amps, starter). But it will confirm an amperage issue (battery or starter).
 
I have my sniper wires directly to the battery and pink wire to the ignition switch.
Double triple check your grounds. Do you have a way to check amp draw with the starter turning the engine over?
 
Metto said:
WTF kind of automotive EFI system cant handle brownouts below 12V during cranking? thats nuts! do you have an oscilloscope? you can scope the voltage at the module during cranking and see what it actually drops to.
Click to expand...
Holley is pissy about low voltage, but will work until about 10 volts.

If your battery and starter are in good shape, that shouldn't be a problem.

I agree with everyone else, triple check your hookup isn't at the wrong location on the switch and it would drop continuity during the startup phase.
 
Bebop said:
Holley is pissy about low voltage, but will work until about 10 volts.

If your battery and starter are in good shape, that shouldn't be a problem.

I agree with everyone else, triple check your hookup isn't at the wrong location on the switch and it would drop continuity during the startup phase.
Click to expand...
Hoping to take a look on Saturday. Thanks
 
Finally had a chance to look at it. Guy who installed it had the startup wire connected to an aftermarket fuse box. For some reason that box is only getting 10 volts on a hot key. Found the old electric choke wire and it has a solid 12 on startup, so I just connected to it temporarily. That works like a charm. Started it up probably 15 times with no issues. Drove it for about half an hour and got it up to temp. Plus I wanted it to learn. Came back, switched it off, and it has a hard time starting once up to temp. The saga continues. I don’t think it’s a voltage issue anymore. Something else is happening when it heats up under the hood.
 
You need to tune the starting enrichment parameters.

www.efisystempro.com

Tuning Your Engine Start-Up

Tuning Your Engine StartupHow efficient is your engine startup? Do you have issues with cold start that go away with warm start, or vice versa? Let’s dig down into that a bit and see if we can help. I am going to write this specific to Holley’s Sniper and Terminator X throttle body EFI systems but
www.efisystempro.com www.efisystempro.com
 
Back
Top