About 2 weeks ago my 4.2 had a slight stumble at idle and my mileage was dropping. I bought a digital meter to start checking my sensors.The reason I did not suspect my plug wires is they only had less then 4k miles on them. After checking the MAF,DPFE,EGR,IAT, I finally decided to check my plug wires. I found the resistance on them to be thru the roof high! The shortest wire was like 16.80. The longest was about 17.20.With resistance like that its a wonder my 4.2 even ran. I went to Autozone and had parts dude put all the types of wires the 4.2 uses on the counter. I checked resistance on all the sets and settled with the Bosch wires. These are only temporary until I can get some better wires,like JBA,Taylor,or MSD. Its been a week now and i'm happy to say my 4.2 is still running great,stumble free and good gas mileage again. I will never buy Motorcraft wires again!

 

I'm surprised that resistances in that range caused a misfire problem. What condition are the plugs in??

 

The plugs,which are Motorcraft AGSF 42FM, are in excellent condition.They were bought with the Motorcraft wires,so they have less then 4k miles on them too.And resistance that "high"? The Bosch wires resistance are 7.20 and lower!

 

That is surprising!!! The insulation can break down on plug wires
and cause a misfire condition. This is usually due to heat and age,
but this should not be the case with only 4K miles. Another thing
that happen is the plug wire against a sharp object, and the insulation will be cut through from vibration.

 

Bob,that would not surprise me,with the way the wires are routed behind the engine then to the plugs.I routed the new wires straight off the coil,over the valve covers and to the plugs.You know how there is one wire in the set that is super long; I used that one on #4 cylinder,but wound it up and tie wired it. When I find a set that is universal,I will then cut them all to one length,that way resistance will stay the same. Any suggestions on universal wire sets out there?

 

I've had good luck with NAPA custom wires. They are made by Beldon, which is a very good wire manufacturer. When routing plug wires, I will usually run them through wire sheathing if there is a place that the insulation could be cut or damaged by abrasion.

 

I had a similar experience with the Mighty Bronco II two years ago. I bought Motorcraft wires and they lasted about 1 year if that. I swaped out with some Bosch (not recommending them just what I had available), and the B2 ran like a champ. Milage jumped from 17.25 to 19.95 MPG. I think the aftermarket Motorcraft don't compare to the Factory OEM's, which lasted over 100K. I will run my F150 OEM's to 100k or whenever I see a problem. I'll not buy another set of Motorcraft either, but the plugs are good. JMO
Tim

 

Blue,

Do you remember what the Taylor's resistance was?

Taylors and MSD's are universal for our trucks, at least the Spiro Pro are, and supposed to have very low resistance. I've had mine on for about 6k miles now and they seem to be working great. I want to run my truck in pitch black to see if there is any arching going on. I keep everything sprayed down pretty good with Silicone spray to help avoid this and protect against water damage but I'd still like to take a look. Assembling the Taylor Universal wires took me about 2 hours. They look nice too and the plug boots on them are bullet proof.

tom

 

Tom,Autozone dont carry Taylor wires,or any hipo wires for that matter. Where did you get yours? Did you cut them to all one length? I did a search and Taylor and MSD have the lowest resistance out there. I did see Crane Cams has some new wires out that claim to be the lowest; they are called Fire Wires. I paid just under $30.00 for these Bosch wires I have now.They are temporary until I find some good universals.

 

who makes the motocraft wires for ford??? i wonder?

 

I think you can order them from here.

http://www.taylorvertex.com/spark.html#spiro

I didn't cut mine to all one length, i didn't even think abou that. Probably a good idea though. I got my set from Murray's speed and custom shop http://www.murraysperformance.com/home.cfm for about 65 bucks I thiink. I have them burried in water every weekend and they seem to be performing well. Truck runs perfect.

Tom

 

With the EDIS firing 2 plugs in series, one in each bank, it is not necessary to make ALL the plug wires equal length. The "effective" resistance will always be 2 plug wires in series. Since the plug wires in bank 1 will be shorter than the plug wires in bank 2, you will have a "short" one and a "long" one in series anyhow, which will balance out.

 

Blue,

I just thought of something. Maybe is was those darn burning crickets that prematurely rotted your motorcraft wires

Tom

 

Them no good,little good for nothing holes!