maupin442

I bought a SCT tuner for my 2011 Ecoboost. Installed it today with canned SCT 93 tune. Went for a test drive and it has made the shudder a lot worse. Before the tune it would only shudder at 70mph WOT. Now with the tune it's terrible. Shudder at half throttle no matter the speed but is the worse at 50mph plus. Anything over 50mph half throttle more causes the shudder to be so bad the check engine light comes on and makes the truck feel like a miss fire until I stop and then take off. I ran the code with the tuner and it says random miss fire. What to do? Please any help will be greatly appreciated!!!

NASSTY

Tighten the gaps on your spark plugs down to .030
It may help and it doesn't cost anything.

johndeerefarmer

Also try a custom tune. The SCT canned tunes aren't that great.

troutspinner

Agreed with Nassty, I just did this but replaced with new plugs gapped at .030. Your problems will be gone!

maupin442

Ok great thanks. I have 60k miles. I will replace and gap the plugs tomorrow. What brand plugs are recommended?

FlameBlueFX4

Either Brisk RR15YS or Motorcraft SP534 plugs.

SkiSmuggs

My plugs were shot at 40K. Suggest 35K replacement intervals. The 100k interval recommended by Ford seems totally bogus.
Your shudder got worse because a tune stresses the system more. I also recommend dropping to the SCT 91 Octane tune as some have had higher knock counts with the 93 tune.

maupin442

Changed the plugs today. Put in Motorcraft Iridiums gapped at .030. The old plugs were badly burnt out and gapped between .045 and .050. Truck runs amazing! No shudder at all. Runs smoother than when I bought it. Thanks for all the help!!!!

cbvet

Good news

Honey Boo Boo

Does this shudder almost feel like a driveline issue? Or is it quite obviously an engine misfire while it's happening?