brian???

truck misfires and goes into limp mode under heavy acceleration every time. have replaced the #5 coil twice, Change plugs and plug brands, gapped down to 30. truck runs fine otherwise, anyone have some ideas?

maplelakeduckslayer

Assuming you mean .030? Check the wire harness itself going to the coils for damage?

antony1103

I second checking the wire harness first and going from there. Last time I had a chronic misfire in an my old 5.4, it ended up being a fuel injector. These misfires can be so hard to diagnose, especially if a new coil back and plug doesn't help at first.

mountaintruck

I had a very similar issue on my 2016 5.0 Two cylinders were misfiring only under decent load. Tried new plugs and swapping coils. Then they replaced the two injectors and that fixed it.

Zakkary Holden Frye

Hey guys I have a similar issue. truck runs great and then at just over 8 psi of boost heavy shudder kills all boost (opens wastegates) and goes into limp mode. Every now and then ill get a cylinder 2 misfire after it happens. I have done ignition coil sparkplugs and fuel injector on that cylinder still shudders over 8 psi. i have AFE stage 2 intake 2 brand new Cavalli Turbos with turbosmart wastegates and blowoff valves. i have a tune but have tried everything from stock tune to MPT performance techs different ideas still nothing. Thanks guys

Bravo3eco

Intercooler weep hole. Condensate in your intercooler is the root cause and the only solution is the weep hole that evacuates the condensate.