Not the most technical question, but I switched from Ngk v-power spark plugs (had 33-35mpg) to Ngk Iridium ($11 per plug) and my mpg dropped to 25-28mpg.

Are the plugs to blame or is there something else that I am overlooking?

The car is stock.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xiaogou &raquo;</TD></TR><TR><TD CLASS="quote">Not the most technical question, but I switched from Ngk v-power spark plugs (had 33-35mpg) to Ngk Iridium ($11 per plug) and my mpg dropped to 25-28mpg.

Are the plugs to blame or is there something else that I am overlooking?

The car is stock.</TD></TR></TABLE>


have you pulled the spark plugs to look at the electrodes?

put the old plugs back in and see if the mileage comes back up. is this the only thing you did since the 33-35mpg?

 

definitely put the old plugs back in and observe mileage. while they're out, check the gap on the iridium plugs.

 

Thanks for the help. I will change out the plugs today (Wednesday) and report back in a week or so. Thanks again. If it matters the only other thing I did was go from Castrol 5w-30 to Mobil1 5w-30.