2011 5.0. Been chasing down a problem with it "missing" for a while now. Quick recap - new plugs, new boots and springs, new MAF, new PCV. Truck very clearly misses (a lot) at appx 1700 rpms.

Mode $06 on a 20 minute drive recorded low single digit misfires (1-5) on 4 cylinders, which all posts I've read suggest is normal. All other mode $06 data is normal.

Here's where it gets weird. Using a little genius, I rigged up a piece of allthread to hold the pedal at a precise and consistent position, and I can turn a nut to set the rpms. This eliminates any possibility that my foot isn't steady.

Yep, when I dial it to appx 1700, it lopes like a drunk chick, swinging as much as 200rpms in either direction.

If I set it any higher than 2500 it's smooth as glass. Idle also stays consistent, but I can feel it's still loping so I assume it's just not as pronounced down at 700.

This is a long running frustrating problem being chipped away one weekend at a time with no progress. Any ideas are welcome.

 

Remember you are dealing with an electronic throttle, not mechanical.

A wild guess, something worth looking into - go get your battery load tested. A weak battery can cause all kinds of weird electronic issues.

 

There's nothing wrong. You'll find most 5.0s will do the same thing sitting on the carlot. The issue is when the cams advance. at about 1700 rpms, the cam profile changes and what you are experiencing is the cams advancing and retarding which they will do at 1700 rpms. Just part of the variable cam timing.

 

I'm sorry but I do not accept "nothing is wrong". This truck ran like a dream when I got it a year ago (106k) - it accelerated, cruised and shifted like butter. Now it's a staggering, non-responsive drunkard that can no longer pull my camper up a hill.

The apparent tuning of the truck loves to shift and "hang out" under 2k rpms, which is exactly where this problem manifests, so it effectively runs like crap.

If I operate with two throttle positions - idle and stomped to the floor - I love it. Sadly, in daily traffic I cannot leave rubber at ever stop light.

Something is wrong, and new plugs, boots/springs, MAF, PVC, TB cleaning, trans drain/fill, and exhaustive vacuum check have not fixed it.

Now thanks for a good idea though - what are the exact details of the VCT advance - is it possible the problem lies somewhere in that not doing all it should properly? And how to diagnose that?