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> Plug wire, spark plugs and dwell, New info on post 24
VaccaRabite
post Apr 18 2019, 04:02 PM
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So my car starts bucking again on todays shakedown cruise (and with the PA roads this spring it is REALLY SHAKING!). I pull back home guessing the #3 lead came off again. With the car running I touch the lead pull it off the #3 plug. While I'm doing this the plug wire is shocking the hell out of me!

Like an idiot I stand there looking at it (as it continues to shock the hell out of me) until I drop it and I hear it arcing against something in the engine bay.

I turn off the car and remove the entire lead (I have coil near plug, the lead is only about 6 inches long). Flexing it all over, I can't find ANY breaks in the insulation. these leads are almost brand new, and only have about 200 miles on them. They are very flexible and the insulation seems to be in great shape. The pulse was jumping through the insulation on the wire and arcing against the powdercoated #3 intake runner, causing the bucking. The coil pack is certainly strong!

I moved the wire as far as I could from the intake runner (the pack is bolted right next to the intake runners, so I can only move it so far) and the car ran flawlessly. I went on a 30 minute drive and it was AWESOME.

So... what next. On a wet day its going to be arcing everywhere. I've sat through that ride before. Maybe make new leads with thicker plug wires? Do I need spiral wound?

@mcmark
@spoke
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windforfun
post Apr 18 2019, 04:35 PM
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Your plug wire insulation is starting to conduct due to a deteriorating dielectric constant for the insulation material. Replace the wire with a higher quality one that isn't made in China. The heat from the engine is changing the insulation's molecular structure. Try going with pure silicone insulated wires.
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fixer34
post Apr 18 2019, 05:12 PM
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QUOTE(windforfun @ Apr 18 2019, 04:35 PM) *

Your plug wire insulation is starting to conduct due to a deteriorating dielectric constant for the insulation material. Replace the wire with a higher quality one that isn't made in China. The heat from the engine is changing the insulation's molecular structure. Try going with pure silicone insulated wires.



Loosely translated, buy new/better plug wires. Are the ones you have the 'resistance' type? Go with copper wire cores.
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rudedude
post Apr 18 2019, 05:59 PM
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Can you use copper core wires with microsquirt?
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steuspeed
post Apr 18 2019, 09:11 PM
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Try running the car in your garage with all the windows blacked out and the lights off. You should be able to see the plug wires arcing.
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porschetub
post Apr 19 2019, 12:12 AM
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QUOTE(steuspeed @ Apr 19 2019, 03:11 PM) *

Try running the car in your garage with all the windows blacked out and the lights off. You should be able to see the plug wires arcing.


(IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif) ,yes we used to do that,if yours leads are bad its a great light show ..not,copper cores are great for a stock application but fall short with modern pointless systems.
Real happy with my Clewitt set as they work with my Pertronix II ,Permatune CDI and transformer coil.
Beru solid core seem reliable and reasonable priced if going stock,not sure if there are more options.
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bdstone914
post Apr 19 2019, 08:26 AM
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@VaccaRabite

What brand wires are you using? I have had good luck with Beru. Even got them at an Oreilly store for 30 bucks.
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VaccaRabite
post Apr 19 2019, 11:38 AM
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I’m not using stock wires.

I think I have everything clocked right now so there is no arcing. Car did great on a 20 mile drive this morning before the next deluge.
I’ve only had about 30 miles since I put the head temp gauge back in, and I have only seen head temps above 310 yet. Need more highway miles for sure, but I was pulling a hill in 5th going 90 and it was running nice and cool.

Need to get these little problems fixed so I can really start driving this car.

Zach
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rhodyguy
post Apr 19 2019, 04:29 PM
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Wet day? Are the rain tray, funnels and tubes in place? Engine bay seals?

With the engine running, in a dark space, use a spray bottle set on mist and spray around the eng compartment.
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Mark Henry
post Apr 19 2019, 08:39 PM
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High power coils? (IMG:style_emoticons/default/biggrin.gif)
They pack a huge jolt, the EMP goes right through the jacket. I strongly advise not touching or pulling the coil wire off of a CDI. Ever! It's enough it could kill you, BTDT had a engine runaway, yanked the magnacore coil wire off on a MSD, almost knocked me on my ass. my arm was tingly numb for a couple of days.
There's a reason for the warning sticker on 911 CDI's and the grounded plug sheathing.

If it's a Bosch blue coil I doubt it's pushing 25k volts, but some CDI, COP, etc., are 60k+ volts.
Unless for sure the wires are substandard, damaged, arcing, or interfering with a sensor it may be a non issue,
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Mikey914
post Apr 19 2019, 08:50 PM
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I'd be suspect of the ran tray.
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VaccaRabite
post Apr 21 2019, 08:18 AM
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High power coil packs, one per cylinder, with about a 6 inch lead going to the spark plug.

I have a GT grill with no rain tray. When I was using carbs I needed all the cool air I could get to keep the engine in line. Longer drives are needed, but I may be able to go back to a standard engine lid now.

Zach
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VaccaRabite
post Apr 24 2019, 06:17 PM
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I may have this figured out. maybe.
I think the heart of it is what Mark H said about the high powered coils overpowering the plug leads.

Monday night the car was bucking. I went into it again with a bunch of ties and tried to clock all the plug wires so they did not touch anything. Today I went for a 40 mile drive and it was perfectly behaved. Not a single buck. So maybe I have this figured out?

Nice afternoon for a drive too.

Zach
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Spoke
post Apr 24 2019, 06:31 PM
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Are there specified wires to use with the high power coils? Seems like your wires are not a good fit for the coil.
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infraredcalvin
post Apr 24 2019, 10:57 PM
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Why not heed the good advice here and get some new quality wires to solve the problem instead of a band aid approach? You’re temporarily fixing the issue with ties, all you need is one to come loose when you’re too far from home and it becomes a bigger (and much more expensive) hassle then the correct fix the first time.
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VaccaRabite
post Apr 25 2019, 09:04 AM
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QUOTE(Spoke @ Apr 24 2019, 08:31 PM) *

Are there specified wires to use with the high power coils? Seems like your wires are not a good fit for the coil.


As far as I know they are the leads that came with the coils (each plug has its own coil).
The kit @McMark built has a coil near plug setup. The plug leads appear to be good quality 7mm silicone leads. The leads are too short for me to see the brand or maker. I suspect they are the leads that came with the coils.

I'm waiting to hear from Mark B. before I order different leads (and If I do they will be custom Mangecore 8mm leads for EFI cars).

Zach
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McMark
post Apr 29 2019, 07:42 AM
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They're 1997-2004 Corvette wires. (IMG:style_emoticons/default/thumb3d.gif)
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JamesM
post Apr 29 2019, 11:30 PM
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Given you are running Megasquirt, I am wondering if you might have an issue with your ignition output settings, to much dwell cranking up the coil output to far perhaps?

I haven't personally run them, but I recall reading conflicting information as to what the dwell setting for those LS coils should be set to and I believe I saw the recommended setting for those change recently. May want to double check.




QUOTE(VaccaRabite @ Apr 21 2019, 06:18 AM) *

High power coil packs, one per cylinder, with about a 6 inch lead going to the spark plug.

I have a GT grill with no rain tray. When I was using carbs I needed all the cool air I could get to keep the engine in line. Longer drives are needed, but I may be able to go back to a standard engine lid now.

Zach


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JamesM
post Apr 29 2019, 11:47 PM
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Just confirmed the MS hardware manual itself was updated as to the recommended dwell to use with LS1 and LS2 coils (assuming you are using these for coil near plug setup)


http://www.msextra.com/doc/pdf/Microsquirt_Hardware-3.3.pdf
"A dwell figure of 3.5ms is advised for LS1 coils.(was 4.5)"

I would check this before spending money on anything.



Fun reading, includes a picture of arcing due to improper dwell...
http://dtec.net.au/Ignition%20Coil%20Dwell%20Calibration.htm
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VaccaRabite
post Apr 30 2019, 08:49 AM
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QUOTE(JamesM @ Apr 30 2019, 01:47 AM) *

Just confirmed the MS hardware manual itself was updated as to the recommended dwell to use with LS1 and LS2 coils (assuming you are using these for coil near plug setup)


http://www.msextra.com/doc/pdf/Microsquirt_Hardware-3.3.pdf
"A dwell figure of 3.5ms is advised for LS1 coils.(was 4.5)"

I would check this before spending money on anything.



Fun reading, includes a picture of arcing due to improper dwell...
http://dtec.net.au/Ignition%20Coil%20Dwell%20Calibration.htm



I've sent a message to the magnecore people but I have yet to buy anything. I will look at my tune and see where the dwell is set.

@mcmark can you confirm that these are LS1 or LS2 coils?

Thanks!
Zach
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