[knightrider_916]

I recently swapped out my stock spark plugs at 91,000 miles on my 98 gt with ngk iridium plugs. $8 each. and put on a set of ford 9mm racing wires, i was hopping to get rid of the pingy noise when accelerating and improve my gas milage. i was getting about 19 mpg before and now im getting 17 mpg. What do i need to do to fix this?

 

[BlueStreak03]

did you change the air filter and PCV valce also?

 

[MAXX RS4]

If your mileage dropped perhaps your running your plugs with the wrong gap size?

But 19mpg wasn't too bad. Right now I'm trying to figure out why I'm getting 13mpg.. :happyhapp

 

[knightrider_916]

My pcv valve is still functioning properly so i didn't replace it. my plugs came pre-gapped, i bought them from sacramento mustang.

 

[BlueStreak03]

You may want to pull them and check the gap to make sure it didn't get closed accidentally during shipping.

 

[mf150]

.052-.054. also check you fuel filter.