Question about a 2018 Ford Escape with a phantom misfire

Just a heads up, I spent a full day chasing a random cylinder 3 misfire on a 2018 Escape with the 1.5L. The code would only pop up under load, not at idle. I swapped coils, plugs, even the injector, and nothing fixed it. Finally, after about 7 hours, I pulled the valve cover on a hunch. The intake cam lobe for that cylinder was worn almost flat. The variable valve timing system was trying to compensate, causing the misfire only under certain conditions. It was a huge pain because it didn't show the classic symptoms. Has anyone else run into this on the newer Ecoboost motors? What was your fix time?

3 comments

3 Comments

ryanprice1mo ago

Man, that's a wild find. But are we sure the worn cam is the real cause and not just another symptom? Those VVT systems are pretty smart at covering up other issues. I've seen similar misfires from a tiny vacuum leak or even a flaky sensor that only acts up when the engine is hot and working hard. It just seems like a huge leap to a mechanical failure without some other checks first.

abby_king221mo ago

Yeah, @ryanprice, that's a solid point about chasing ghosts.

sandralee28d ago

A buddy of mine had a similar situation with his truck a few years back. He spent weeks chasing a rough idle, swapped the VVT solenoid, cleaned the MAF, even did a compression test. Turned out it was a cracked vacuum line under the intake manifold that only showed up after the engine got hot and flexed just right. By the time he found it, he'd already dropped money on a new cam phaser kit he didn't even need. Sometimes the obvious answer is just the one you want it to be.