Ok guys, here's one. Got my '14 3.5EB mid summer with 42K miles on the clock. Everything worked perfectly. Since it hadn't had the plugs changed, I did that the first week, gapped them at .028, cleaned the three MAP sensors, and replaced the air filter. Then I did a PCM reset and TB reset.

Ever since then, it pops and puffs on first start after getting cold. Clears up within 30 seconds at most, but I "think" that I've been hearing it skip a beat from time to time now when idling, even after getting warm. I did pull the plugs back out and open them up to .030 to see if that might help, and did a computer and TB reset as well again. It didn't help. No codes.

Any idea of how can I troubleshoot this? Some will say it's normal, but my dad's nearly identical truck with 70K miles on it (and original plugs) doesn't do it.

 

Sounds like you have a poor connection somewhere.

 

These trucks are programmed to run rich on the open loop fuel cycle. I understand the other truck doesn't exhibit this behavior, but each truck is different.

A few things I would check
1) Re-inspect those plugs for cracked insulators. You may have a very small crack you can't see. Better yet, just replace them.
2) All vacuum hoses, PCV connection, etc.
3) Intake/turbo piping tubing clamps.

More invasive - Scope the intake ports in the heads for carbon buildup.

 

I'm thinking of throwing the old plugs back in to see if it does it before blowing money on another set of new plugs. Blew some cigar smoke over the engine while the fan wasn't running, didn't see any being sucked in or blown around like it shouldn't be... Does anyone have a recommendation for a scope that will work well? I borrowed one for my '04 to check out the tops of the pistons, but it kind of sucked, just barely fit, so I could only see about 25% of the Piston top.

 

Did you properly torque the plugs when you installed them?

 

I just bought a cheap $20 flexible one on amazon that connects to my phone. There are a ton of them to choose from with varying quality/features. I had my intake removed and it was easy to see the amount of cabon buildup in the heads. I would think with a flexible scope you should be able to get in there with the intake still connected, at least to look at a few cylinders close to the front of the engine. You might want to consider removing the throttle body so you're not fighting the flapper with your probe.

 

I think your plugs are to tight no?
i thought only tuned trucks run at that gap

 

That's why I went from. 028 (at first), to .030. Still too small of a gap? I've heard a ton of guys doing .030.

 

Absolutely. Just a very tiny dab of antisieze on the threads too.