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Discussion Starter #21
Update:

Apologies to all for no recent updates, it has been hectic for me lately.

So after grounding the engine to frame and body, battery to frame and body and re-tuning my IAC via the throttle plate screw, the car now runs like a champ without the hood on. A Holley tech (that has more experience with EMI issues than the other techs I talked with on the phone) also helped me along the way. Today I am going to add some grounds to my hood and finish re-wiring my electric fans (for a cleaner look). The Holley seems unaffected by my basic chrome 14" air cleaner. I believe I have also found what to look for on the Holley files to find EMI. Things such as having multiple readings in the same time frame.

Here is a list of what I have done to solve my miscellaneous EMI issues so others on this forum can hopefully solve them:
-keep MSD/CD box coil wires (black/orange) away from EVERYTHING.
-ground engine-frame-body, as well as battery-body-frame if possible.
-run as many wires behind a firewall or as far away from engine bay as possible. NO RUNNING WIRES ACROSS ENGINE BAY BY SPARK PLUG WIRES OR DISTRIBUTOR.
-MSD/Holley trigger wire (white) is very sensitive. Shield and keep away from all "high voltage" wires.
-remove unused wires from Holley connectors.
-use resistor style spark plugs and spark plug wires, fouled/old spark plugs increase EMI.
-twist wires together (ex. MSD green/purple) to help reduce "cross signal" between wires.
-many alternators are noisy, keep Holley wires away from it.
-Holley power and ground directly to battery. Recommend doing to MSD/CD box as well.
-ground air cleaner if needed.

If there are any additions, feel free to add them. I believe my EMI problems are solved. Thanks for all the help and for y'all's patience.
 

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I had EMI issues as well. I separated all my High Voltage ignition runs from low voltage (this helped a lot) but still stalled once in a while. Final fix (knock on wood) is changing my old spark plug wires. This seems to have fixed final issues. If the connection between plug and wire is even loose a bit it will spark and this spark will cause ECU to reset (at least in my case). Fresh connections fixed it.........Using recommended 3924 plugs for AFR heads....

It's amazing how sensitive the system is to interference, but totally fixable.....
 

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Discussion Starter #25
Are you saying that your car runs well except when the hood is on?
Correct. So I will be grounding the hood as well. It has been rainy in my area so I haven't had a chance to make sure the hood is still contributing to my EMI.

My theory on why this happens is that the distributor is close to the hood so it may reflect some EMI it creates, thus angering the Holley.
 

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Correct. So I will be grounding the hood as well. It has been rainy in my area so I haven't had a chance to make sure the hood is still contributing to my EMI.

My theory on why this happens is that the distributor is close to the hood so it may reflect some EMI it creates, thus angering the Holley.
If you have a steel hood it should already be grounded to frame really well. Have you gone around and actually taken an Ohm meter and measured these things you are grounding. If it reads "0" Ohms from you negative battery terminal to the item then it's already perfectly grounded. My thinking is you have a noisy +12V signal (mine is run right to my main 12V circuit that is switch on and off with a battery disconnect) or a bad HV connection somewhere in your ignition. All the grounding in the world will not fix a bad connection issue.

After dealing with similar gremlins the things that fixed my issue:

1. Moved my spark wires away from ALL the low voltage wires, rerouted my CD to coil wires away from all low voltage wires. If a spark induces emf in your low voltage wire then this is a big problem for Sniper.
2. Routes my spark plug wires so adjacent cylinders are not running next to each other
3. Replaces my spark plug wires with MSD silicone wires and put stock autolite 3924 plugs back in vs. race plugs
4. Replaced my coil wire
5. Replaced my 12 year old CD box with a MSD digital 2
6. Ran my Sniper switched power directly to my battery line (has a cut off to shut off the sniper)

So basically both my main power and switch power are going to battery (the cleanest source). In all of this besides my engine block to frame and alternator to frame I have not added a single ground to my system. All my Sniper issues were fixed by doing 1-6....
 
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