peteb

at 98K installed Motorcraft SP-534 plugs and gapped to .32 per ST 3 Motorsports. Besides breaking the little red tabs, went fine. Freeway shudder went away, but MPG went from already disappointing average of 16 to 14.5. Any thoughts? Thanks

acadianbob

I think you need to take multiple measurements over a longer period of time before you conclude there is a mileage difference.

SkiSmuggs

Did you torque to 133 in/lbs or 11 ft/lbs? Dealer over torqued mine and it went from one plug missing to 3 plugs missing just from that. I use the Torque Pro app to check the misfire count. I am gapped at .028 and get 20.5 summer and a lot less (17.8) in winter. Gas makes a difference too. I was getting in the high 16s with Gulf 87 last winter, switched to Mobil 93 and the fuel mileage went over 18. I am currently running Mobil 89.

jtravisl

I just picked up a set of SP-534. Was checking the gap...all came .030 when I noticed on the side of the box... Caution: Spark plug gap is not adjustable. Torque 10-20 N.M 7.2-14.4lb-ft.

what's the discussion if the plugs aren't really adjustable? Have we all been damaging the plug to get to 0.28?

Thankful for 50 degree days in January in KC... hopefully it will be a quick job and no freezing my tail off.

Tothemax

Make sure your torqued them properly and you dont have a cracked plug. Also hand calculate your fuel mileage over the course of a couple tanks of fuel.

jtravisl

74k miles on a 2011 EB.

Install was easy and fast... about 90mins. Could have been 60 mins if I had 6" longer arms. Big shout out to the guys on these forums for the walk thru. Matched the old plugs to cylinders and each plug came out at .043 to .045. Went for a test drive... BOOM . extra power I had forgotten about. And no miss at high rpm in the 60-70mph range. Did a passing test... blew the doors off the mustang in the right lane.

Hand torqued each. And put some anti seize on ... just in case.

Viking1204

This is what I did too. Had misfires and replaced the plugs with the new ones gapped at .30 and haven't had anymore misfires. Old plugs were all gapped at .40.

Houlio44

Well damn! I can't wait to change my sparks now!
What plugs did you buy?

jtravisl

I bought the SP-534 plugs. Got them from Amazon about $2 per plug cheaper than the local ford dealer. Same plug. They came gap'd at .030.

winchested

They say don't gap on the box cause there are lots of stupid people...