Just got off the phone with SM ENGINES and they are NOT selling holley sniper kits because they are having major problems with rfi and holley is not helping . All this after I bought one !!!!!!

Just follow the instructions regarding wire routing and you'll be fine. Remember this hobby includes people that use romex and wire nuts as acceptable practice for underhood wiring.

I've installed a lot of Sniper kits and most of the time they work just fine. I did run into one unit that had RF issues. Summit replaced that one under warranty and the replacement worked fine. The Snipers work okay for a low dollar EFI unit. They are better than some of the other choices on the market but they aren't the best EFI option available. The Holley Terminator X Stealth is only $200 more expensive than a Sniper and it has fewer problems but some customers don't want to spend the extra $200.

Keep ALL the wiring away from the alternator and ignition wires and you will be fine. NOBODY makes EFI that tolerates RFI gladly.

If you are using the magnetic pickup in a stock or MSD distributor, you need to run shielded cable right to the pickup itself. The noisiest RFI place on earth is inside an ignition distributor.

Kevin

Are you having issues yourself? If so, what plugs/wires?

Had RFI issues with a FiTech system. Used the cheap stainless covering you can buy to make regular vacuum hoses look like braided line. Soldered a ground wire to the braid and ran all the wiring through it. Fixed all my issues and it doesn't look bad either.
https://www.ebay.com/itm/224228250078?hash=item34350b91de:g:-EcAAOSwETVfqXwG

I would think that would be the best way. With the Holley system I found it interesting the shielded portion is left open and not grounded

EDIT- I take that back. It's not grounded externally at the harness but through the ecu at pins J&K on ignition connector.

https://documents.holley.com/558-431_crank-cam_ignition_harness_diagram.pdf

Had to return kit because of faulty wiring . SM took it back and sent me a used spare till Holley will repair it . Holley will not give a return date ? 6 months a year don't know . Steve Morris is a great company by the way helping me all the way.

Interesting! Were you able to determine what the problem was with the wiring or just sent it back for them to sort out?

I suggest you have the shop check your alternator for excessive AC voltage as well. Best to connect volt meter at the alternator, AC selected, elevated rpm with an electrical load (lights etc.) Anything over .5V and it's time to hook up the oscilloscope to confirm.

I've seen several driveability issues in the last few years that were traced back to a faulty rectifier in the alternator.

As for RFI, are you running non-resistor spark plugs and/or metal core wires?

I would think a capacitor wired into the batt and ign. leads for the Sniper module would take care of any issues.

Firecore wires , and the right plugs.

Is it grounded correct?

I fought this problem with FAST EFI

Ground plane, shielding, and magnetic chokes all help.

Mine is great. Zero rfi issues. I'd prefer a separate ecu type system in the future but it's been a good system. Gotta really treat it like a new toyota. Very sensitive to voltage, grounds, battery amperage, etc. New wiring throughout the car. Quality connections & splices. Etc. Not saying they're not having issues otherwise but many, many units are out there performing. My remote tuner is tuning probably 4-5 a day, every day it seems. Definitely not a system where you just replace the carb and use a bunch blue butt connectors and roll.

That is correct. A Sniper is not a simple carb replacement, especially on a Mopar. There are a lot of things that need to be changed before the Sniper "bolts on". I prefer to start with a new engine compartment harness and go from there.

EFI and old wiring/electrical systems sometimes don't get along. Very good idea to update systems on car so they all play well together.

When dealing with high frequency noise energy, surface area is your friend. Use braided cable for ground connections between major components with the largest, clean contact surface you can get under the screw. Most people like to use a star grounding configuration where cables are only bonded at one end but it some circumstances, it pays to ground both ends of a shield.

Andy what EFi do you recommend for my 440. I was thinking about going to an Elderbrock Pro flo and getting a size bigger injector as I’m pushing close to 600hp. The tech at Elderbrock told me they only made 2 MAPS for my application that only worked below 12 pounds of Vacuum. I can’t remember what I have but it will be close as I’m running a xr286hr. Any help would be appreciated. Thanks.

take a look at this tread, may help you make a choice.
link


Joe

I'm not a fan of the Edelbrock system since it is a "black box" which can't really be tuned. FAST used to make good stuff but they have fallen behind now. I would never recommend FiTech even though some people have good luck with those systems. Same with MegaSquirt, I'd never use a MS system or recommend it but there are a lot of MS fans out there who will talk about how great their system is for hours on end. Only thing I recommend these days is a Holley system. The Sniper is the entry level throttle body, next step up is the Terminator X so probably one of those systems. The HP and Dominator systems are much more expensive and complicated and really need a pro to install.

My sniper 4500 has been pretty good. It learns well, it runs well I did wire it per the manual, and I did upgrade my alternator big time.
I would also prefer the ECU was separate.