Holley Sniper and EMI/RFI Issues

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rymanrph

rymanrph

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I installed my Sniper system last summer and I've been having some erratic issues. When driving the car coming off throttle, the car can either stumble or completely die. It doesn't happen all the time - sometimes it doesn't happen at all, but one time specifically I had to keep my foot on the gas to keep it from dying. It's rather annoying having to restart your car and traffic lights.

I sent a couple data logs to Holley and he concluded that I had EMI/RFI because of the negative timing in the data logs. On the log, the time doesn't start at 0, it starts at like -80 seconds and works its way forward.

Anyway, I'm trying to figure out how to eliminate these issues. Holley recommended moving my coil further away from the Sniper unit (it's mounted on the back of the intake currently) and also moving the MSD ignition box wiring away from the Sniper wiring. This is rather difficult since part of the Sniper wiring actually connects to the MSD box.

I read a couple articles that mention spark plug wires could cause a problem as well. I have 8mm Taylor wires that are only 4 years old. When I run the car in the dark, the coil wire glows anywhere it touches anything and I can see a slight flicker/glow at each of the spark plugs. Should this concern me or is that normal? I'm trying to decide if I should replace my wires or not. Holley recommended 8.5mm wires, but I don't want to pony up for new wires if what I have isn't the issue.
 
EMI can be so bad there has been cases of MSD units triggering themselves. The spark wires can have so much energy, and depending on routing, that they transmit interference into the dist. trigger and re-trigger (false trigger) the MSD

Isolate sensitive wires such as your distributor trigger, and run it as close to a ground plane as possible, and avoid having extra wire laying around

Don't parallel the trigger wires with plug wires. Separate them if possible, and cross them as close to a right angle as you can

Examine your grounding, I'm not really familiar with the Sniper.

There was one case ......a guy claimed the (Ford front distributor) was interfering anytime he installed the air filter pan on a sniper That post is on the Holley forums, somewhere
 
Take care with the two coil primary leads. On an MSD the coil -/+ leads carry a high energy pulse. This could generate a significant electromagnetic problem. The longer these wires the worse

Also "I think" MSD does NOT recommend solid core plug wires. Research what they recommend and follow that
 
The Taylor wires I have now are spiral core, so I'm not worried about that, but the glowing has me concerned. I'm trying to decide if I want to replace them or not.

I'll be shielding the coil wires and taking a look at the distributor trigger wire. MSD sells a replacement cable that is shielded that might be worth looking into as well.

The Sniper is directly connected to the battery (positive and negative) which is what that installation instructions specify.
 
anytime you see glow/spark out of a cable means the insulation has been compromised. Id invest in the fattest primary coil wire you can get, like an 8.8 or larger. Get an AM radio and position it close to the motor, I bet that thing sounds like a hairdryer. Also make sure your distributor/crank pickup leads are shielded but only on one end (not connecting the 2 sides) that comes from a Megasquirt post and they are very prone to RF interference.
 
Also make sure you twist the wires coming from your distributor to the throttle body and as an added measure slide braided steel mesh over it and ground the one end of the mesh.
 
superchargeddrt said:
Also make sure you twist the wires coming from your distributor to the throttle body and as an added measure slide braided steel mesh over it and ground the one end of the mesh.
Click to expand...

I found that MSD makes a shielded and grounded replacement cable; I'm going to give it a try. It sounds like you've had your share of issues as well.
 
rymanrph said:
I found that MSD makes a shielded and grounded replacement cable; I'm going to give it a try. It sounds like you've had your share of issues as well.
Click to expand...
Oh yes I did have my share, that's for sure. Please let me know how that cable works out. I'm in the process of puttingin a 416 stroker and it might be a good idea to use it.
 
In obstinate cases, possibly a plastic vehicle, you can purchase shield twist and run it around the sign wires. Ground this and ONE END ONLY.
Try not to dismiss "torques in progress" like an alternator with a terrible diode, which causes hash and spikes on the 12V transport.
It's not simply EFI. A person on another board was enduring impedance between a MSD and the voltage controller. The MSD made the guideline go crazy.
You referenced rotor staging. There has been situations where even production line wholesalers have staging issues.
 
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