Eric7575

Yeah I think that was my problem that my truck ran super smooth then I got a tuner and the can tuned worked great but when I got my MPT performance tune it ran like crap(truck completely lost power when under full throttle like the sparks were getting blown out) and they suggested re gapping the spark plugs to.030 which I did and then I noticed the rough idle and the shuddering although the MPT costume tune now ran fine (one exception...the shuddering which it would now do with any tune and even stock so I either messed up a gap on a plug, there is a tire not properly balanced or my truck does not like the .030 gaps). Now I want to order the new 2013 plugs since they come pre gapped at .032 and I will know that it was not my poor gap job. I wont be gapping them at .030....see if that fixes my shudder (by the way the shudder is barely noticeable but it still bothers me). If my MPT performance tune does not run well then so be it as I don't use it that much. I like the power it has but I don't like the fact that you cant tow with it. If you got a truck that you cant tow with then why even bother with a truck? My SCT canned tune runs great on 87 octane, it increased my gas mileage by 2 mpg and it gives me 400 ponies with over 500 ft/lbs of torque and the best of all is that I can tow with it so I can use my truck for its intended purpose and I don't need to carry my SCT tuner with me all the time. MPT said I should try their tow tune as it would be faster, more powerful and I can still tow with it since it was designed for just that.....I don't know that I will though because like I said.... I really, really like my 87 octane SCT canned tune that I can tow with. My trucks stock gapping was all at .035

ceh527

I'm having the same issue as well. Put in the 534s, gapped to .30, and now have a markedly rough(er) idle.

bignfast

Sunday I changed out my plugs to the 534's gapped to .029. My truck has just over 40,000 miles and so far has been problem free as far as the powertrain goes. The factory plugs were all between .040-.042 and looked pretty good. I must say The process of replacing the plugs could not have been simpler. I used a 8mm socket to remove the coils, 5/8 spark plug socket a variety of extensions, and of course a torque wrench to snug them down to a mere 11 ft. lbs. The biggest thing Is just being careful not to crack the new plugs. (Be gentle and don't over tighten). I have only drove it to the grocery store and around the block for a test run but so far a it idles smooth and pulls hard with no misses or roughness. Happy with the results so far but had no problems to begin with.

brucesears

You probably cracked one of those new plugs, it's happened to several people already. You can crack one of those suckers by looking at them crooked. It's very easy to tighten them too tight.

Bills96TA

Well I just swapped out my regapped stockers for some new 534's and it instantly smoothed out the idle. No more shaking at idle like it was after the regap (didn't do it with the stock gaps). Also I took it for a drive and it feels better as well as the mileage appears to be coming back up where it used to be. This was just a quick 20 mile loop but I was able to keep the green bar above the line way easier than after regapping the stockers. I will say that the 11ftlbs is so minimal it just seems wrong but thats what it says to use. None of my stockers were cracked/damaged and all were around .28-.30, the new ones are dead on at .34. I also put a dab of dielectric grease on each plug boot before installation.

BucketMan

Did mine today. Seems a bit smoother at idle, but no real appreciable driving difference. I had re-gapped my old plugs though.

Ordered from Rock Auto, best prices out there and fast shipping.

Am I the only one that did this without a torque wrench?

justjimmy

I dropped a can of Seafoam in my tank and that took care of my idle. Smooth now.

SkiSmuggs

Have you been using Top Tier gas as recommended by the owner manual?
http://www.toptiergas.com/retailers.html

We know they use the same refineries, it is the additives that make them different.

justjimmy

Yes. BP almost exclusively. The rest is Mobil.

Have been since new - approaching 50,000 miles.

brucesears

I did mine without a torque wrench, I wrapped my hand around the ratchet and used almost no force to tighten. Went back and checked to see how hard they where to take out--easy.