EDIS- magnetic interference btw EDIS and coils...any recommended physical distance-

[nvrstuk]

between coils and the Exploder EDIS?

I'm running two 4/pack coils and want to mount them within 6 inches of the EDIS. Anybody know if there would be any stray frequency issues mounting the coils close to the EDIS?

thanks

 

[DirtDonk]

When you say EDIS, are you referring to the main computer/ECM/ECU module thingy? Or a separate ignition control module of some kind? Not sure if these had one of those, but if so, not sure how sensitive it is. Many engines (such as my Buick V6) mount the ICM (ignition control module) right under the coil packs.

Interested to hear what others say. Have you PM'd EFI Guy about it? At least to let him know about this thread to make sure he sees it.

Paul

 

[nvrstuk]

Yes, Garry's not sure how far they need to be apart or if it's a problem at all.

EDIS- the small 3'x4" rectangular shaped module (from an Exploder) that has 12 wires coming out of it that controls when the coils fire by receiving the trigger from the crank sensor which in this case is also an Exploder part.

I'm not too worried about each coil pack being 2" apart. My concern is the EDIS "module" being within 5" or so of a coil.

thanks!

 

[EFI Guy]

EDIS is built in to the PCM on the Explorer. You are using a separate EDIS module so your situation is somewhat unique. I have only used the EDIS module method a handful of times on Mustangs and always mounted the module on the shock tower (like it would have been done in the EDIS donor).

I don't think you will have issues mounting it on the same bracket as your coil packs, but it is a valid concern and I'd hate for you to have to re-wire it because I said it was ok. So, I'm actually going to punt on that question but my reasoning for thinking it will probably be fine is because the EDIS module essentially does the same thing as a TFI module would, and the TFI gets mounted straight to the distributor. Just make sure you use the shielded wire where needed (and ground the shielding) and don't forget the radio noise suppressors.

 

[Broncobowsher]

Not exactly what your plan is, but it sounds interesting. As mentioned, probably OK, but I doubt anyone has done what you are planning. I hope it is mounting everything to the body, not sure the EDIS module will live a long life if mounted to the engine.

 

[nvrstuk]

Plans are for the EDIS to be mounted to the firewall... good point on the TFI's proximity to and being mounted directly on the distributor.

Thanks again!!!

 

[Broncobowsher]

Come to think of it, TFI on the distributor only sees the high voltage of the plug wires. Not the high magnetic fields of the coil(s) that are typically remote mounted on the fender. As precautionary I would have a piece ferrous metal (gounded) between the two. Or at least the potential to add a piece later if there are issues.

 

[pcf_mark]

I have EDIS with the coils mounted on the front of the engine using a modified (heavily) Explorer bracket. The EDIS module on the Explorer is mounted up front on the rad support on 5.0 trucks. I believe this is because it needs to be cool for longest life. These things seems to be bullet proof but mounting it to the engine seems like a bad idea. It has an aluminum mounting flange / heat sink. If the mounting point is hot then the heat will go into the module and not out of the module.

I first had mine way in the back right corner of the engine compartment so it would stay dry and it worked fine. I then moved it to the left side because I had more room. It has never given me any issues. What WILL get you in trouble is the pickup wire from the crank sensor. Running it any kind of distance from the front of the engine to the module it will pass spark plug wires. The factory wire has an internal shield that protects it from interference plus the module was on the rad support in front of all the "noise". This can cause EDIS misfires that had me losing my mind. If / when you extend your wires to put the module out of the way (mine is tucked under the fender now you can't even see it) go to Home Depot and buy security / alarm system wire. It is really cheap and is fully shielded. This stopped my misfires right away.

 

[nvrstuk]

Thanks for the tip on where to get shielded wire. Got a HD only 50miles away!

I would assume that running the crank sensor trigger wire anywhere close to the alternator would cause the same noise issues as running it close to plug wires...

Running 3 wires from the crank sensor is easier to hide than the dozen wires from the EDIS.. maybe I'll "double shield" those three ...

Keeping it cool anywhere under the hood is the biggest issue... maybe just mount it in the cab on the firewall on a heatsink...

 

[nvrstuk]

Another question on the EDIS module, shouldn't the heat sink have dielectric grease on btw it and the heat sink like HEI pick-up modules and other electronics that are sensitive to heat?

 

[pcf_mark]

You only need shielded wire on the pickup sensor wire all the others are fine. The big spike from ignition causes the interference not the alternator in my experience. You can mount it anywhere in the engine compartment away from the enigne - firewall, rad support, fender wells and be fine. Just not something that is making heat. I have my ECM inside the cab and could have mounted it in there too but I was running out of room in my glove box!

The factory did not have any goo when I pulled them but maybe it had dried up. Does not hurt for sure! It will also prevent corrosion from building up on the backside of the module.

 

[nvrstuk]

Thanks for the info... I found shielded wire by the foot at HDepot and am mounting the EDIS in the cab... I also moved the coil mounts two inches farther away from where the harness comes thru the firewall...just to be safe "r"...

 

[ransil]

Another question on the EDIS module, shouldn't the heat sink have dielectric grease on btw it and the heat sink like HEI pick-up modules and other electronics that are sensitive to heat?

heat sink grease and dielectric grease are 2 different things.

 

[nvrstuk]

Thanks, I realize there is a big difference btw the two "greases" as many refer to them.

See below:

Here is a good comparison on heat sinks and different compounds used on the bottom of them.

"Here is measured data of a few sample greases with 30 watts heat dissipation:
Type Sink F Device F Delta degrees Percent (aprox)
Bare scratched 62.0 63.9 1.9 3.1%
Heat sink compound thick 55.9 57.6 1.7 3.0%
Bare polished 61.6 63.0 1.4 2.3%
Vaseline 62.5 63.1 0.6 1.0%
Dielectric grease 62.3 62.8 0.5 0.8%
Heat sink compound thin 56.2 56.6 0.4 0.7%

Best result is at bottom. All greases were tested under "scratched" conditions by roughing the heatsink with ~300 grit paper.

Using too much dense grease, like thick heatsink compound, greatly increased thermal resistance. This occurred because compression pressure was not enough to force excess grease out of the area between the heatsink and the resistor tab. When the layer was thinned to a light "wipe" of grease, thermal resistance fell off significantly.

There is essentially no difference between Permatex Dielectric Tune Up Grease and a special heatsink compound used on high-power transistors. Even Vaseline, at 1%, is better than bare metal-on-metal."

I couldn't post the table showing all the variables.... http://www.w8ji.com/dielectric_grease_vs_conductive_grease.htm

Thought I'd just toss this out there...since it also talks about too heavy of a film being detrimental...