Hey all,
I've got a question for someone. My '98 SC 4.6 5-sp Lariat has 104k on it; at 95k, I replaced the original plugs with Bosch Platinums. I didn't notice a power or response improvement, but I did notice a significant mileage improvement, and it has run fine from then to now. Well, about a month ago my Check Engine light came on, and I started to notice a pretty lumpy idle. I took it in, and the mechanic told me it had a misfire on #4 and #8, or whichever ones are at the back on each side (boy, were they fun!). He suggested a new set of plugs, to which I responded, they are basically brand new. I definitely don't have the money to pay him to do a plug change when they've only got 9k on them, and I don't look forward to doing it again myself anytime soon. Anyway, he cleared the codes and they didn't return, even though the lumpy idle lasted a week or so longer. Today the Engine light came on again, even though I don't think I've noticed the idle problem. The one thing I didn't do when I changed the plugs was replace the wires, and they're original with 104k. Could they be the cause of the misfire? I don't want to accept that anything's wrong with my new plugs, and of course they would have to be the two hardest to change. Does anybody have any suggestions? Even though I can't really afford new wires right now, I would love to have a reason to have to buy a cool-looking set of blue wires. I appreciate any advice. Thanks.

 

the "lumpy idle" sounds like you may have an injector unplugged. check all your connections and be sure they're ok. your wires are probably on the way out and you should change them when you get the $, but you may be able to clean them and smear them heavily with boot grease and get by for a while. mine were breaking down in the boots and causing random misfires. this was on a replacement set i got from pepgirls and they were lifetime guaranteed. now, whenever they get dirty, i have them swap 'em out for a new set.

 

If your truck ran good until the plug change, go back to what you did last: you changed plugs. Put dielectric grease on the boots to seal out moisture and avoid misfires to ground. Make sure the boots are on the plug good; I've got one new wire that liked to back off once a week but a new crimp on the terminal fixed that problem.

With 104K on the truck, the wires are probably ready for a change. Take your pick of brands, and there are plenty of them out there; just choose a good one. I went with Borg/Warner 8mm from O'Reillys and I've been pretty happy.

Good luck.

 

Put wires on it. Check the back two plugs to make sure they are not fowled. 100 + thousand miles on wires is a lot and they will break down.

 

Start with changing the wires.....104K they are ready to go, especialy if you have removed them. They could be arcing. The other thing about a misfire can be caused by the platnuim plugs....ALOT of vehicles do not like them and DO misfire because of them. I have seen alot of cars with them in there and not run right, when you put the factory recommended plugs back in, all is good. Start with the wires.

 

I would take out those aftermarket plugs and put in
the wires and plugs that were factory specified!