Folks, I have a 95 Cougar XR-7, 4.6 ltr, V-8, I bought new in Oct 94. Since, I have put my fourth spark plug wire set on. The Cougar has only 58,600 original miles. This past summer when I had a mechanic put in a new evaporator and heater coilfor the A/C and heater he mentioned out of the blue that it was a great engine but blows spark plug wires. My thought was......no kidding because at that time I had put on three sets. Recently, I put on the fourth set I was speaking of. A week later it was acting like the spark plug wires were shot again. I parked the car out of frustration. I have not drove it for about three weeks and today I cranked it up and it ran like a champ. I even drove it around the block a few times putting a load on it and it ran perfectly. Any ideas how I can fix the problem with the spark plug wires and any idea why it would run like crap and then all the sudden purr like a kitten? Inputs are greatly appreciated.

Not all plug wires are created equal. Most auto parts store wires (Bosch, etc.) are inferior to factory/OEMwires; especially on cars whose ignition systems are "senstivie" the quality of the wires. Use either Motorcraft or, even better, Magancor wires (which are more expensive but are excellent wires). Other than wires, you may have a bad coil-pack.


What makes you think it is an ingition-related problem? What are the symptoms when it runs "bad"?

Thanks Sheebeehuh for the reply. I had bought a coil a couple years ago thinking that was the possible problem too. Put it on one side no difference, put the new coil on the other side no difference. Actually, I even thought it was the transmission at one point and took it to AMACCO transmission place and the tech hooked a computer up to the system as I drove the car and he said he thought it was the plug wires. I left and changed the plug wires and it ran like a champ.


When it runs rough it acts like it is missing. I have changed spark plug and made sure the gap is correct. I looked at the injectors and replaced all the o-rings.


Today, I went and scraped the battery posts and battery connectors and it fired up like a champ. But not sure if that is the problem or not. I hope this helps with your troubleshooting as I am frustrated and I appreciate your assistance.


Maybe I should buy some of those spark plug wires your talking about. Thanks again and if you have further advice please let me know. Much appreciated.

Drive it for while and see if the battery cleaning really made a difference.


I would suugest a good set of Motorcraft or Autolight plugs and either use either Motorcraft or Magnecor wires. For some reason, the 4.6L does not seem to like Platinum plugs (they don't seem to last and can make the car run worse) so don't waste your money. Get some good copper-core plugs like Motorcraft or Autolite. Be careful when changing plugs as our 4.6L engines don't have much thread depth in the spark plog journal. Don't tighten too much and be careful when removing the old plugs if you decide to get new plugs in addition to the wires.


Also, you might try pulling the MIL codes to see if any cylinder misfire codes have been set. These don't necessarilty set the Check Engine Light.

Thanks again Sheebeehuh. The cleaning worked fine for a few days. Then yesterday when I went to crank it, it made the clicking soundthree or four times then turned over. Do you think I need to replace the starter celenoid or the little black relay or whatever it's called in the fuse box in the engine compartment?

It mayjust bea bad battery or alternator. How old is your battery? How cold is it where you live? Cold weather KILLS weak batteries.

i agree with sheebeehuh i had grand marquis that gave me the same issue when the alt was week put in new one and it went away ....lots of local auto parts store can do tests of charging and starting systems on your car for you if everything checks out ok don't rule out the coil due to the fact i have had more than a few 4.6's come through the shop with intermitted misses like thatand they resulted in a hair line crack in the coil's sometimes moisture would getin there then they would run like crap then other days they would rungreat i would also recomend the motorcraft wires i myself try to stay with the factory originals for the car little more money but worth it in the long run..........

Buying motorcraft wires is definitely an investment for your much priced cougar.

_______________________
Cougar Seat Upholstery - Get the Seat upholstery in Cougar Parts and Accessories Catalog by Auto Krafters Inc.

https://cimg1.ibsrv.net/gimg/www.mer...e67260aca3.jpg
The MOTORCRAFT ignition (spark plug) wires that were installed at the factory have a VERY HIGH FAILURE RATE -- it was a well-known problem with the early 4.6 Liter engines, due to the original wires having a damage-prone, carbon-strand core.
The original Motorcraft wires would often fail right after a spark-plug change (wires not handled carefully), and replacing them with more Motorcraft wires doesn't solve the problem.
After the expensive Motorcraft replacement wires failed, I found that the reason for the failures is the carbon-core of the wire, which breaks and causes arcing inside of the wire.
I solved the problem with the BOSCH #09725 Premium Wire Set -- The Bosch wires have a spiral-wound, stainless steel core that doesn't break down like the original Motorcraft wires.
I had 2 sets of Motorcraft wires fail before discovering the problem. After switching to the Bosch # 09725, the problem is gone.
'95 MERC now has over 165,000 miles of trouble-free ignition performance, and still going strong!
The Bosch wires are getting hard to find -- but keep looking, 'cause they are WELL worth the effort !!
When installing the plug wires, do them ONE at a TIME !! Be careful to match the old wire's length to the new Bosch wire.
A drop of PermaTex Dielectric Grease on the coil-side end of the wire will prevent terminal corrosion.
I used cheap plastic Wire Looms to hold the wires in place and prevent cross-fire.
The Correct Spark Plugs for your '95 Cougar's 4.6 Liter engine -- BOSCH # 9605 - Double Iridium electrodes.
When installing the Bosch plugs, USE NO Anti-Seize -- Use Synthetic engine oil instead !
Torque the plugs to 200 inch/lbs. for proper seating and plug thread integrity.
Good Luck !!