Finally got the hang of diagnosing those intermittent misfires on the newer Ford EcoBoosts

Spent about 4 hours last week chasing what I thought was a bad coil on a 2018 Escape, only to find it was a tiny crack in the plastic charge air cooler pipe that only leaked under full boost. Cost me a solid half-day's labor I couldn't bill for. Anyone have a favorite smoke machine for finding these kinds of leaks fast?

3 comments

3 Comments

brookes371mo ago

Man, those plastic charge pipes are the worst. I've seen them crack right at the molded seam where they connect to the turbo. The leak can be so small you can't hear it, but it dumps enough unmetered air to set lean codes and misfires. A good smoke test is the only way to catch it before you start throwing parts at it.

aaronallen1mo ago

Yeah, that "molded seam" you mentioned is a killer spot. I've pulled a few where the crack was hidden underneath a factory clamp, so you couldn't even see it until you took the whole pipe off. It fools you because it'll hold a little pressure at idle, then just blows open when the turbo spools. Makes the car run like total garbage for a second, then it's fine again. A smoke machine saves so much headache on those.

ninah1010d ago

That "holds pressure at idle then blows open" thing you mentioned @aaronallen, that's exactly what got me too. Checked it cold, held fine. Warmed up, still looked okay. But the moment I took it for a test drive and hit the gas hard, it all fell apart. What nobody talks about is how the heat cycling softens that plastic over time. You can have a perfect seal in the morning and a leak by lunch after a few heat cycles. I switched to a handheld fog machine from the hardware store. Cost way less than a pro smoke machine. Put the fog in at the intake boot instead of the charge pipe, pressurize it gentle, and watch where the fog gets pulled in. Catches those tiny cracks that only show up when the engine is hot and under load.