Holley Sniper EFI kit - should I try and self install?

Aussie78Z28

Member
Nov 17, 2017
48
I actually just about finished up installing and plumbing an Aeromotive Gen II Stealth tank. Went with the 200lph pump. My old tank was dented, crusty, and would've needed to be drilled or something to get a return line into it. If it had been in mint shape I probably would've gone with that Holley drop in unit and cleaned the old tank, but the Aeromotive tank is $500 and it's painted, assembled, baffled, and ready to run out of the box. The in-tank pump on that thing is dead silent too, all I can hear is the relay clicking on and off out by the battery. Curious if it'll be audible once it's loaded down with 58 PSI though, currently regulated to 6 PSI to run the soon to be retired qjet. Ran 10 gauge power and ground wire through the inside of the car, following the rest of the wiring that runs through the trunk and up to the front. Aeromotive insists on 10 gauge (12 minimum) to minimize voltage drop, not because the pump draws an unusual amount of current or anything.

I have a Firebird so my original 3/8 fuel line runs up the left side, and there are 1/4 and 5/16 vapor return and EVAP lines on the right side. I actually put a charcoal canister back in so I'm using the 5/16 line for that. The 1/4 line was unused so I trimmed and rebent some of it to make a template to use for bending the 3/8 feed and return lines to run along that side. I mounted the 10 micron filter below the right door, which allowed me to make the feed line 2 pieces to ease the bending and installation. I also split the return line in the same area and have a -6 AN union there to join the front and rear sections. I went with Earl's Vapor Guard hose and hose ends because I just don't see the need for fancy braided stuff for how I use this car.

I spent a long time hemming and hawing about how to do the fuel system on this thing. Even made a spreadsheet of the different options and prices and narrowed it down to the combo that made sense. Then spent even more time doing image searches and thinking about how to route everything because I didn't want to accidentally end up with something annoying to service or routed poorly/in the way of something else. At some point you just gotta decide to start doing it and hope you aren't short some critical part. I did it by myself on a driveway with the rear end up on some ramps and that seemed like plenty of room. I wouldn't say any of it was hard to do, just time consuming and sometimes tedious depending on how fancy you get.


Next step will be to install a Holley Sniper. I was actually going to do just the fuel system and stop there because I want to swap in a Gen III 5.3 or 6.0 at some point, but a new opened but unused Holley Sniper popped up for a low enough price that I couldn't ignore it, so it seems the BBC will be hanging around for a while longer if it doesn't grenade randomly.

My fuel system's not exactly pretty, but I'm happy with how it turned out. I'll try to take a few pictures tomorrow when I go fiddle with it more -- still need to empty and remove the old feed line before really driving it.
Awesome mate - thanks for taking the time to step through the process. I really appreciate it :)
 

rburrow87

Veteran Member
Apr 6, 2016
155
San Diego, CA
Took a few pictures after finishing up with yanking the old line out.

Wasn't really sure how to end the lines once they got into the engine bay, so I just kinda have them hanging out by the fender well there. I made a bracket out of some flat stock to attach them to so the ends are supported, can just barely see it in the picture.

The clamps I went with for the groups of lines are a bit too large. The next size down I had at the time was too small.

IMG_20191005_124255.jpg IMG_20191005_160232.jpg IMG_20191010_184832.jpg IMG_20191010_184840.jpg IMG_20191010_184849.jpg IMG_20191010_185037.jpg IMG_20191010_185049.jpg IMG_20191010_185505.jpg
 

rburrow87

Veteran Member
Apr 6, 2016
155
San Diego, CA
Got my Sniper installed! Started around 4:30PM on Friday and worked until it got dark, then started again today around noon and stopped around 8 PM. Only drove it far enough to pick up a celebratory cold beverage, gotta double check everything and wrap it up when there's some light out tomorrow.

First time running, didn't catch the actual startup because I figured it'd start and die a few times first, but it lit off and kept going after only a couple of tries.


Still need to run the wire for the screen inside along with the AC kick/shutoff wires. My tach is kinda junk anyways so I'm just going to make something to mount the display in front of it. Probably only going to use the AC kick wire for now, don't feel like adding a relay and junk for the shutoff. I've read that it works fine without the AC kick wire, but it's easy enough to tap into the Vintage Air clutch relay to do it.

I have a 4th gen radiator and fan setup and also set the fans up to run like they do in 4th gens, where they run in series for a low speed and parallel for high speed. I was using a BMW 2 speed coolant switch but I moved them over to the Sniper.


All in all, it's not too hard to install. The most time consuming parts of my install were the fuel system and wiring. Not hard honestly, just time consuming.

My fuel system was pretty involved since I replaced the tank and made new feed and return hard lines. Rubber/braided hose definitely would've been easier of course. If you go with that drop in Holley pump and sending unit and your stock 3/8 hard line is in good shape, you can just replace the couple of rubber sections with EFI hose and clamps and be done with it since it doesn't need a return line.

The wiring really is very simple. Just needs to be hooked up to the battery, switched 12v ignition, tap into coil negative, and power to the fuel pump. The other big connector is entirely optional. You don't even need the screen plugged in all the time, only for monitoring or making changes. It took me a good amount of time to wire up because I've made several wiring changes over the last few years (and gotten better at it) and I wouldn't have been able to sleep at night if I just slapped this on top of all that spaghetti. I also took the opportunity to move the coil positive wire over to a relay so the ignition switch no longer has to carry that load.

I watched a lot of videos of installs and first starts with basically everyone saying how nicely it runs and it still blew me away that it started and ran pretty great on the first try. Probably going to add a HyperSpark distributor and coil after using it for a while.

The gas pedal is definitely touchy like everyone says. I'm going to see if I get used to it first before making changes though. The built-in return springs are quite strong so I'm not running return springs like you would with a carb and the pedal effort feels nice. Seems like it'd be uncomfortably stiff if you ran the usual dual return springs and had a kickdown or TV cable for the trans.
 

grzewnicki

Veteran Member
Lifetime Gold Member
Dec 9, 2009
3,781
Gordon from Jacksonville Fl
I'm on week 6 of a MSD EFI install...of course ran into numerous issues. Found rust on trunk drop off so had to cut out and make patches. Decided old spare tire hold down had to go since it was unused in its location and fabbed up new one while tank was out. then when picked location to put it it was over that brace so I couldn't bolt it in since I couldn't get to bolt threads that were hidden under brace so welded in (yea could have done that later on). During wiring decided to follow MAD electrical's suggestion about using a junction block to run all my accessories off of and re-wire my higher amp alternator with their kit. And got rid of adapter plug at old external voltage reg and wire alternator correctly. Probably should have done that when building car 7 years ago. My back is killing me from leaning over fender splicing in wires with butt connector, crimped soldered and heat shrinked, all very neatly. GOne through a million zip ties, tying wires in place, cutting to right length, then cutting zip ties to get wire back out so I could splice of put a round terminal on end. Decided to go with harness tape versus the plastic convoluted wire covering so it looks more factory. Ran a power wire from horn relay to headlights for when I do relays. The fuel lines were another issue since MSD says don't use hard lines. Trying figure out a route for 2 AN 6 lines was a hassle, got feed line in following old lines route, then checked web and an MSD tech said you could use hard lines if using a return line system, so had to wait for the line to come in, all the lines are clamped to frame rails, holes for screws drilled and tapped or used nutserts on rear frame area since it is thinner and won't accept threads. Coming together though, one more wire to run from junction block to starter and put a weatherpack connector on pos and neg wires going to pump and wiring will be done. I had taken a week off of work first week of Sept figuring I'd knock out the install in a week, yea that was a pipe dream.
 

rburrow87

Veteran Member
Apr 6, 2016
155
San Diego, CA
I want to share what I have going on so far with the Sniper so others have more things to consider while installing theirs. It runs beautifully, EXCEPT, I either have a bad IAC valve or an EM interference issue. My gut says bad IAC because I don't see anything odd in the data logs, but I'm reading that it's much more likely that it's an EM issue. Sounds like the Sniper is a bit sensitive to interference.

What's happening is the IAC will desync and creep open each time I press the gas (since it opens the IAC a bit when you're on the throttle), or it'll just randomly decide to open it 100%. The ECU will show that it's at 0 the entire time but the valve is clearly open when it happens.

Just for fun, I tried wrapping the Sniper wiring closest to the spark plug wires (which are a good distance away IMO) with some leftover reflective heat shield sleeve to see if it would help shield against EMI, and it did improve somewhat.

Since I want to have the Sniper control timing anyways, I'm going to go ahead with installing a HyperSpark system along with MSD Super Conductor 8.5mm wires. I know a couple of my plug wires (Taylor Street Thunder) are questionable at the spark plug end as they tend to pull off of the cable and have to be re-crimped every time I take them off, so that may not be helping.

I also reviewed the wiring diagram for my car and realized that the +12v ignition switched wire I'm using for the pink wire on the Sniper and fan relay coil power is actually tied to literally everything in the car that uses +12v ignition switched, so it's possible that's contributing as well.

With the full HyperSpark system, the distributor and CD box will both need +12v ignition switched, and from what I've read, they're "clean" so they can safely be bundled with the Sniper's +12v ignition switched wire. The HyperSpark CD box will only use that as a signal to turn on and has separate power wires that go directly to the battery. Since I changed the original HEI +12v wire to run a relay for better power to the distributor, I will be able to repurpose that new HEI power wire as a dedicated (and theoretically "clean") +12v switched ignition source for the entire Holley system. Hopefully that does the trick.
 

rburrow87

Veteran Member
Apr 6, 2016
155
San Diego, CA
Got the full HyperSpark system installed today. The distributor alignment tool was neat, just needed to advance it 4 more degrees to sync it up with the Sniper. Only took it for one 30-ish minute drive, but so far the IAC issue seems fixed. It also runs a bit smoother and more responsive. I was using ported vacuum for the vac advance before and I think the ported vacuum being on the secondaries was making it pull in the extra advance weirdly and/or late. The Sniper's timing table seems a bit strange and I ran across this video showing how to copy over a better table for a starting point.

I added the Holley 20-16 throttle lever extension and the gas pedal feels MUCH better. I had to add a return spring with it too. Unless you have some kind of aftermarket gas pedal with a different lever ratio, it is absolutely essential IMO. I noticed it's out of stock everywhere, but EFI System Pro had them in stock.

I also picked up a y-harness and USB cable so I can use my laptop instead of having to shuttle logs and changes back and forth with the SD card. Haven't hooked them up yet though.


So basically, here's what I learned installing the Sniper:
  • Seriously consider adding HyperSpark to complete computer control. Not the worst idea to get it to work without it first, but I did end up going back into the same wiring harnesses I did while adding the Sniper to add it cleanly, so keep that in mind.
  • Take the original HEI/coil power wire and make it control a relay for the switched 12v wires (unless you have a better source). If Camaros are the same as my Firebird, the 12v ignition switched connections are all spliced together under the dash.
  • Get the Holley 20-16 lever extension or make your own extension because the pedal is ridiculously touchy otherwise. It also makes the pedal travel feel more normal which progressive linkage wouldn't change. The progressive linkage would also make the ported vacuum port useless. I'm using it to control the purge valve on a vapor canister.
  • Keep spark plug wires and any other "noisy" wires (like the coil power wire) away from any of the Sniper wiring. If you have strange issues, consider replacing the wires and/or spark plugs. The HyperSpark CD box allows further isolating the ignition since the switched 12v is just to turn it on, and of course you can move the coil further away compared to coil in cap setup.
  • Clean the engine and repaint the valve covers before taking pictures.

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rburrow87

Veteran Member
Apr 6, 2016
155
San Diego, CA
Still cautiously optimistic on the IAC thing until I get more time on it, but yeah that was an adventure! I'm pleased that it all went in and worked with no major drama, aside from having to drop the tank and open it up the day after installing the Sniper because Aeromotive forgot the hose clamp on the pump outlet. Thankfully I found that out while it was idling in the driveway before leaving. Here's hoping it stays drama-free.
 

Fbird

Veteran Member
Lifetime Gold Member
Feb 12, 2011
6,501
atlanta, ga
glad to here....
When I injected mine (circa 2008) took me almost a yr. Didn't have "drop in pumps", self learning ecu...INTAKE manifold!!!...
BUT
all eventually went surprisingly well (Holley commander 950)
Actually ran.... later it drove....lost the motor before I ever got to tune it...(something EXTRA between the head and piston :( )
I forgot more about the "tuning" than i can even remember now.... :(
one day the BIRD will rise again..
 

rburrow87

Veteran Member
Apr 6, 2016
155
San Diego, CA
Have about 150 miles on it since installing the HyperSpark and I can confidently say that the IAC EM interference issue is fixed. Surprised it was interference because the data logs had no signs of it. The IAC must be more susceptible than everything else in the system.

Unfortunately, I'm going to have to drop the fuel tank again at some point because it seems like the float is getting stuck and/or dragging on something in the 1/2-3/4 area. So much for the Aeromotive tank being ready to run out of the box. Didn't occur to me to look at the level sending unit when I had it out and opened up to add the missing hose clamp on the pump outlet. I don't think the sensor is hung off of the sending unit like a stock unit so I never saw it. I thought about taking the tank apart after receiving it but I didn't want to mess with the factory assembly...
 




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