I'm having trouble with spark plug wires.

I put new wires on shortly after I bought my F-150. I went with the Advance Auto, 8mm Xact-Fit wires. I had great service from them for years, never any problem. I put short tube headers on after one of my manifolds split 3 ways. Evidently the plug boots didn't like the extra heat and 4 of them fried, one of them clear to the terminal.

I replaced them with a set of 8mm Accel Super Stocks, next step up in the price range. Right off I had nasty spark-rattle in 3rd through 5th gears. I traced the problem to my wire routing, rerouted for a more parallel run. Rattle got better, only in heavy 4th acceleration and 5th acceleration. As spring came in with warmer temps, the rattle got worse.

I did put new spark plugs in at the same time, but the new plugs are the same Autolites with the same gap as what came out. I have trouble accepting that the plugs are the culprit since I've never had a bad Autolite plug.

I replaced the wires with another set of Xact-Fits and installed heat shields over the plug boots (plug boots are holding up just fine). The rattle reduced a lot but is still there on hot days and very heavy 4th and moderate 5th accelerations. (Conclusion : Accel Super Stocks suck)

I can only deduce that the problem is crossfire between the wires as the condition only started with the Accel SS's and reduced with rerouting and a wire change.

Is there a brand of wire that you guys particularly prefer? I'd rather not keep wasting money until I find the right set of wires.

An option : I do have a set of Moroso 11mm Blue Max 800ohm wires that are destined for another project. These are the cut-and-terminate-to-length wires and I do have the ends necessary to connect to my stock distributor. Would I have any RF or other issues with running these on my F-150? Moroso says "no", but they are designed for race engines with far less electrically oriented engine bays.

Another option : I suppose I could run a jacket on every other wire in the route to serve as another layer of insulation between the cores. I'm not particularly interested in the engine bay looking like a total jury rig.

Thanks!

'92 F-150 4x4, 5.0L, 5sp, short tube headers, otherwise all stock.

 

Try some looms for the wires....You can get the ones that utilize a VPC bolt, and then there's the ones that simply seperate the wires....In your position, I'd check into both....

Also, if its a v8, check between the #7-8 wires.....They're notorious for wire arcing...

 

Just got finished re-running the wires and swapping in some good (and shorter) wires from the first re-wire (I always save good old wires for such an occasion).

I've been looming all of my wire installations, but even then it seems that you've always got a couple of long loops of wire, particularly at 3,4,7, & 8. I've used the shortest of all of the non-Accel SS wires.

I ran the longest 3 wires to 4, 7 and 8; running along the valve cover to come around to the plugs from the aft end of the heads.

I also streamlined the dizzy ends as well, trying to minimize wire crossing at the cap.

Hopefully that'll do it. I'll know in the next few days.

I'm not familiar with these "VPC bolt" looms.

Thanks!

 

The 5.0L and 5.8L engines are very susceptible to cross-fire caused by improper plug wire routing. This info from Steve83 comes in handy from time to time:
Spark Plug Wire Routing | SuperMotors.net

 

Well that makes sense, 7 and 8 are run along side each other. The trick is to not run adjacent firing wires directly beside each other. I've been looming them in bank order without regards to firing order which puts 7 and 8 together. 2 and 4 have been separated by at least 3. I'll take another gander.

Thanks a lot!

 

This is why I make my own wires also and not use built to fit. I have accel on my 87 Iroc that I installed no lie in the mid 90's 93-94ish still going. Car only has 100K on it. Also using them on the 351 with the routing in that link above, no issues. I had a hell of a time with Belden pre-made wires but that was mostly the routing.

 

rla2005 - You're advice was dead on. 2 and 4 are separated by 1 and 3 and the closest. 7 and 8 are run away from each other entirely and are no closer than having 4 and 5 between them at the distributor. I can't even make it crossfire now.

Thanks a ton!!!

 

Thanks for reporting back! Glad to hear your problem is resolved.

 

Sorry to hijack the thread, but I believe I have a similar problem, but on a 92 5.8. Does anyone have a link for wire routing on the 5.8, the link provided was for 94 up 5.0 and 5.8 engines. Feel free to pm it to me, post it here, or post it in my thread https://www.ford-trucks.com/forums/1...vibration.html Thanks in advance!

 

I think the 5.8 and the 5.0 have the same firing order. Regardless, the trick is keeping adjacent firing wires from running along side each other. As long as you keep adjacent firing wires separated by at least 1 wire (preferably 2), then your firing order is superfluous.

Further update : made a 1400 mile round trip to SC and back to NJ with a lot of 100 degree driving...not one crossfire.

 

move wire number 8 (closest to the driver, drivers side) out of the loom and the crossfire will go away