Hi ,
I own a Equinox LS 08, last fall (09) I had a misfire code when the car was going to overdrive from 55 to 60 mph. I replace the spark plugs ( to Bosh 2) and added "dry gas" to my gas tank. Cleaned the "throttle body and valve" and after the repairs the car was running fine.

After 10 mo. the engine been misfiring at 60 mph. No codes are recorded. It's that the engine burns the spark plugs and wires are arching at high temp.
Only 34k miles;
Should I used a more expensive plugs and replace the wires?

 

misfires often indicate the presence of excess fuel, or moisture in the fuel system, you could switch to a higher octane fuel, or switch fuel manufactures, its not uncommon now a days for them to use more ethanol instead of the detergents they were using ... schools out on which engines benefit more from a higher ethanol presence, fully fuel injected or trottle body...i would switch manufactures first and add something which would remove any moisture you may have acumilated

 

when all else fails, go back to stock...lol....throw some delco plugs and wires in there, and dont buy cheap gas from a non name station.......see how it goes from there....

maybe run some FI cleaner on the next fill up....

 

Clean/replace O2 sensor.

 

put dielectric grease on the spark plugs, they need it as soon as moisture gets in there they will corrode it a bit throwing off your computer and it is a cheap and easy thing to try if it isnt the problem, i would listen to geezz and use name brand fuel too, all non name brand gas stations use fuel that was rejected after transport and this is why they offer much lower prices