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View Full Version : Should I replace my spark plug wires?


Jeff d
04-16-2012, 11:19 PM
I've got some high speed/RPM stalling issues. At the moment I'm pretty sure it's NOT a spark plug wire related issue but I went ahead and tested them with an ohm meter anyway. I saw around 4,000-6,000 ohms per ft of wire. I'm not sure what these should read from the factory but that seems pretty high.

It's an '00 Maristar w/ the LTR and 300 hrs. The wires on there are red 8 mm taylor wires and I think they are original (i.e. 12 years old) based on their appearance and the general lack of maintenance it seems the previous two owners did.

Also, since it's the LTR and the wires are not the typical 5.7L Indmar ones it looks like unless I want to spend $120+ for an OEM set I will just need to get a universal GM V8 set like this:
http://www.jegs.com/i/JEGS-Performance-Products/555/40206/10002/-1

They have stainless terminals too so they should do well in a marine application.

And this crimp/stripping tool to put the ends on the coil pack side:
http://www.jegs.com/i/MSD-Ignition/121/3503/10002/-1

$53 shipped sounds a lot better unless someone else has a reasonably priced source for ones already made up to the appropriate lengths to reach the coil packs at the rear starboard side of the engine.

Does it sound like they're due for replacement? And if so should I just go with that Jegs cut to length kit?

Brian B
04-16-2012, 11:43 PM
I have the same engine and had the same symptoms. Replaced fuel pump, checked wires, coils, replaced plugs........ Nada.

When I took a closer look at the coil packs after running one day, they had water splashed on them from bilge water. (Theyre mounted pretty low in the hull) I pulled the coils, cleaned connections, and used a ton of dielectric grease on all terminals. Problem solved.

Good luck

mtajpa
04-17-2012, 12:54 AM
Jeff d
Brian B was the one I was referring to in your earlier post about the coil pack system. Also check your ECM connectors I am posting some pics of how I found mine.
1st pic you can see how water is getting onto the ECM from the pylon.
2nd pic is the corroison in the J2 connector.
3rd is after I installed a cover over the ECM.
4th is the connectors viewed from the inside of the engine compartment looking forward. They are directly under the pylon.

Just a suggestion hope it helps.

Honkity Hank
04-17-2012, 08:43 AM
I've got some high speed/RPM stalling issues. At the moment I'm pretty sure it's NOT a spark plug wire related issue but I went ahead and tested them with an ohm meter anyway. I saw around 4,000-6,000 ohms per ft of wire. I'm not sure what these should read from the factory but that seems pretty high.


Normal range is 10,000 ohms per ft. so these test okay. If the coating is showing signs of wear or cracks in the boots etc then replacement is indicated.

Jeff d
04-17-2012, 09:52 AM
I already cleaned up the coil pack connections (removed coils and harnesses, cleaned with contact cleaner, scrubbed blade terminals with a scotch brite pad, reassembled with dielectric grease). That's when I tested the spark plug wires since one end was already disconnected. Sounds like they're still within spec.

My ECU has a "shield" of sorts over it that yours doesn't appear to have. I still will pull those connections apart and clean then grease the seals if the ignition coil cleaning/greasing doesn't do the trick.

Sounds like my sparkplug wires are still good.

CantRepeat
04-17-2012, 10:13 AM
Normal range is 10,000 ohms per ft. so these test okay. If the coating is showing signs of wear or cracks in the boots etc then replacement is indicated.

10,000 per foot would be on some really crappy wires. Even the no name brands from Auto Zone should be around 8,000 while really good 8.5mm MSD wires are under a 100 per foot.

Jeff d
04-17-2012, 08:53 PM
Well I did a sparkplug wire test that I saw on youtube where you spray a light mist of water on the sparkplug wires while the engine's running in the dark and look for arcing. I saw some arcing from the #8 wire at the coil pack to the adjacent coil pack. I also saw some arcing from the # 2 wire to the alternator bracket.
http://www.youtube.com/watch?v=xXAFQa0R9hA

FWIW I sprayed much less water than the dude in that video.

The arcing in both cases was from seemingly random parts of the wire that were insulated (i.e. it wasn't coming out of the boot which could be controlled with dielectric grease) with no apparent damage.

So, I went ahead and ordered the above Jegs wire set. Resistance is supposed to be 500 ohms per ft. They charged me a $9.99 "handling fee" though which raised the total to $65.47

We shall see how that plays out.

kmd205v
08-16-2012, 12:04 PM
I have 1998 LTR and it uses up spark plugs causing deteriorating and rough idle. Change plugs about once a year and problem goes away. Should I try a different plug?

thatsmrmastercraft
08-16-2012, 12:10 PM
I've got some high speed/RPM stalling issues. At the moment I'm pretty sure it's NOT a spark plug wire related issue but I went ahead and tested them with an ohm meter anyway. I saw around 4,000-6,000 ohms per ft of wire. I'm not sure what these should read from the factory but that seems pretty high.

It's an '00 Maristar w/ the LTR and 300 hrs. The wires on there are red 8 mm taylor wires and I think they are original (i.e. 12 years old) based on their appearance and the general lack of maintenance it seems the previous two owners did.

Also, since it's the LTR and the wires are not the typical 5.7L Indmar ones it looks like unless I want to spend $120+ for an OEM set I will just need to get a universal GM V8 set like this:
http://www.jegs.com/i/JEGS-Performance-Products/555/40206/10002/-1

They have stainless terminals too so they should do well in a marine application.

And this crimp/stripping tool to put the ends on the coil pack side:
http://www.jegs.com/i/MSD-Ignition/121/3503/10002/-1

$53 shipped sounds a lot better unless someone else has a reasonably priced source for ones already made up to the appropriate lengths to reach the coil packs at the rear starboard side of the engine.

Does it sound like they're due for replacement? And if so should I just go with that Jegs cut to length kit?

Great looking crimping tool.