Spark Plug Wire Good?

General karthief · Oct 11, 2016

Not knowing zackly how to use a vom I set the dial at 20k ohms setting and got 7.4 on a 8 mm plug wire about 20 inches long. Good?

Mustang5L5 · Oct 12, 2016

Ford's spec is 7K ohms per foot.

Sounds like you are below that. How does it compare to the other wires?

Moosee1955 · Oct 12, 2016

A bad spark plug wire either has a 0 reading if it's burnt through or dead. The other reading is real high, like 300 ohms or higher. Example a 2 foot wire that's ok will be around 25 to 40 ohms. If in doubt take your ohmmeter to parts store. Ask your parts guy or girl to measure a new loose wire. That way you have a reference for yours.

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jrichker · Oct 12, 2016

Moosee1955 said:
A bad spark plug wire either has a 0 reading if it's burnt through or dead. The other reading is real high, like 300 ohms or higher. Example a 2 foot wire that's ok will be around 25 to 40 ohms. If in doubt take your ohmmeter to parts store. Ask your parts guy or girl to measure a new loose wire. That way you have a reference for yours.
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Your numbers are way off unless you are using metal core wires like Taylor.

Mustang5L5's number are right on track and I would use them

Mustang5L5 said:
Ford's spec is 7K ohms per foot.

Sounds like you are below that. How does it compare to the other wires?

General karthief · Oct 12, 2016

Tested a couple other wires on car and got 30 to 35 readings tested a unused 7mm wire and got zero. I am going to replace the wires but not with accels. Need 90 degree boots cause I'm putting my gt40p's on. Right now checking out why my #1 cyl reads 240 degrees at the header and the rest are at 340 to 400. Running codes and a compression test. It runs like it has a sparkplug wire plug is slack. Motor has like 30 to 40k on it but sat for awhile unused. Keep ya'll posted.

Mustang5L5 · Oct 12, 2016

What ohm range do you have the meter set to?

Is 30-35 really 3000-3500 ohms?

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Moosee1955 · Oct 12, 2016

The 0 reading is probably because your not contacting both ends. Had the same thing happen the other day, messed around and got lead of meter to contact, reading shot up. Like mustang5L5 said your lower reading was because your setting on meter was on lower setting. Either way your wires fine that you tested. As far as lower Exaust temp on one header pipe, you could have a loss of compression/ output in that cylinder. Do a compression test, and cylinder leak down test on all 8 to see condition of engine. Also be sure theirs no blockage of Exaust or restrictions. How does car run? Loss of power? Anything out of ordinary? By the way 7.4 is 7,400 ohms! Perfectly normal.

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General karthief · Oct 13, 2016

Runs ok does have a very slight stumble off idle when cold. I had the bucking problem with the previous motor but have resolved that by going through the check list jrichker provides on here. Ended up needed another computer. I did notice when stretch ing it out that it seens to find some power above 4k rpms kinda like when the old 4 barrel carbs kicked in if you can remember that. Other than that it's good. I need to pull codes again just to see if anything funny is goin on. I've had the rag for about 14 years and most of the problems have been self inflicted.

Mustang5L5 · Oct 13, 2016

Pull codes and run the cylinder balance test portion after the last engine running codes have been flashed. To initiate the procedure, blip the throttle once the code reading is complete. The engine will idle up a tad, cut fuel to each cylinder, and see if there is a change in output to the o2 sensors. When done, a code 9 (or 9 blinks) means pass. 1-8 blinks means problem on that particular cylinder

General karthief · Oct 13, 2016

Don't ya have to hold the clutch pedal down too? Gotta go back and reread that post. Been a while.

Mustang5L5 · Oct 13, 2016

You can if you want, but the switch on the clutch pedal is wired in parallel with the NGS on top of the T-5. If all of that is untouched, and this is an original 5-spd car, then either leaving the trans in neutral, or pressing the clutch in, will close the loop and prevent code 67.

If you run the codes and get code 67, press the clutch in and hold it. But then you know you have some issue with the NGS on top of the t-5

General karthief · Oct 13, 2016

Its original 5sp car with unmolested wiring. Thanks I will let you know.

mikestang63 · Oct 13, 2016

Just know that when you switch to one of those HP low ohm spark plug wires, it can make the car run leaner. Not such a big deal for N/A cars, boosted another story.

jrichker · Oct 13, 2016

mikestang63 said:
Just know that when you switch to one of those HP low ohm spark plug wires, it can make the car run leaner. Not such a big deal for N/A cars, boosted another story.

???
Can you explain why?

Moosee1955 · Oct 13, 2016

I'd like to hear how a low resistance wire could affect fuel to air ratio too. It's just providing an easier path for the spark to travel. Battery to coil, through module, or points if old school through wires to plugs. Ka boom!

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mikestang63 · Oct 14, 2016

I'vr read over the years Rick Gorski from Firecore50 wires has done some extensive analysis on this.

http://www.yellowbullet.com/forum/showthread.php?t=321168

Mustang5L5 · Oct 14, 2016

I would think the EEC would see the lean condition and fatten the injector pulse width. Only problem might be at wot

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Spark Plug Wire Good?

General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

Moosee1955

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jrichker

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General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

Moosee1955

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General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

General karthief

wonder how much it would cost to ship you a pair

mikestang63

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Moosee1955

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Spark Plug Wire Good?

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