A common misfire scenario with many Ford models with the EcoBoost engine is that of an engine that misfires only during starting up, which then settles down shortly afterward running as you have normally experienced. This is especially true if it has been sitting for a few hours or overnight with what mechanics refer to as a "cold start."
If the misfire is significant enough, you might see a check engine light warning and/or one related to your engine's coolant level, signaling a low fluid condition. There could also be some white smoke coming out of your tailpipe momentarily, indicating that some coolant has gotten into the cylinders and is being burned off.
Related article: Exhaust Smoke Diagnosis Explained in Detail
Causes of Engine Misfire
Regardless of the engine type, all engines will show signs of misfiring from any number of common causes―some relatively minor and some that are very serious.
A misfire in a Ford EcoBoost engine that occurs only during startup can result from various factors, often associated with the cold start process. Potential causes include:
- Ignition system issues
- Fuel delivery issues
- PCV system issues
- Engine sensor issues
- Internal condensation moisture issues
- ECM Calibration Issues with an outdated or faulty engine control module
Diagnostic Approach to Narrowing Down the Cause(s) of a Misfiring Engine
To pinpoint what is going on with your misfiring engine, a mechanic will commonly employ diagnostics based on a combination of his experience with a particular engine and the standard diagnostic recommendations of a thorough examination of the ignition, fuel, air, and engine control systems for misfiring engine repair.
The four basic tests typically include, but not always in this order, depending on the mechanic and his initial diagnostic guesstimate:
- Performing a cold start test to confirm the owner's complaint and to observe engine behavior during startup for any unusual sounds, smoke, or odors.
- Inspecting hoses and the manifold for leaks.
- Checking the spark plugs, coils, injectors, and sensors for damage or wear.
- Scanning for trouble codes using a scan tool that will identify specific diagnostic trouble codes (DTCs), possibly related to the cause(s).
A Misfiring Ford Engine Diagnosis Example
From the same garage that provided viewers with their lists of both the most expensive cars to maintain and the least expensive cars to maintain based on what their customers paid over the past two years, the host of the Royalty Auto Service YouTube garage channel is back with a very useful explanation of why an intermittent misfiring engine is a worrisome problem and what diagnostic tests are commonly used to determine the cause.
“We have known about these Ford EcoBoost engines for a while now, but because of the influx of issues in the shops the past couple of months we felt we should do a quick video showing how to test if this is an issue with the one you have in your shop or if you are testing at home,” states the host.
To see how a diagnostic is done on a misfiring 2014 Ford Fusion with a 1.5L EcoBoost engine, follow along with the YouTube channel's host and his guest as they walk you through the process.
Related article: Why Ford EcoBoost Engines Fail Demonstration
The value of this video is that while the host does not show an entire diagnostic tree to follow as you might use in a Ford repair manual, they instead showed how a garage approaches the problem by first and foremost following Ford's recommended service bulletin on this particular model. In addition, the added value to this demonstration is the devil-is-in-the-details diagnostic techniques they provide.
This short video is well worth watching in its entirety; however, if you prefer, a summary is provided below the video.
Ford Had Some Major Issues With These Engines!!
Diagnostic Tests on a Misfiring EcoBoost Engine Summary
First Check: Is the coolant level low and if so, why? Low coolant level could be due to an owner not maintaining the car's fluid levels or it could be that the coolant cooling the engine block is seeping into the cylinders. To test this the mechanics followed a TSB (Technical Service Bulletin) from Ford regarding this particular EcoBoost engine using a simple pressure test of the cooling system to check if leaking is occurring and if so, where.
Second and Third Checks: Based on TSBs from Ford, the mechanics did a trouble code scan, which revealed a possible problem with cylinder #3. Before going any further with any other cylinders or other possible causes to investigate this trouble code, a borescope was inserted into the spark plug hole of cylinder #3 to look for signs of coolant intrusion while the coolant system was still under pressure from the first check. They found coolant leaking past the cylinder head gasket into the cylinder.
Diagnosis: A leaking head gasket in cylinder #3 requiring immediate repair.
What Happens If You Wait Until Later to Diagnose and Repair a Misfiring Engine: The warning from the host is that if you have an engine misfire as this car did due to coolant getting into the cylinders, you risk damage to both the oxygen sensors and, worse yet, the catalytic converter. The coolant will damage the precious metals that make catalytic converters so expensive as the coolant makes its way from the cylinders and is exhausted into the catalytic converter.
"Platinum will be damaged by coolant… don't let this problem go on too long," warns the host.
For additional Ford engine-related articles, here are three you need to know about as well:
- Ford EcoBoost Engine Replacement Issue with These Model Years You Need to Know
- Ford EcoBoost Engine Oil Breakdown Problem
- Ford EcoBoost Engine Owners are Getting the Wrong Repair Part Warning
Timothy Boyer is an automotive reporter based in Cincinnati who currently researches and works on restoring older vehicles with engine modifications for improved performance. He also reports on modern cars (including EVs) with a focus on DIY mechanics, buying and using tools, and other related topical automotive repair news. Follow Tim on Twitter at @TimBoyerWrites as well as on Facebook and his automotive blog "Zen and the Art of DIY Car Repair" for useful daily news and topics related to new and used cars and trucks.
COMING UP NEXT: I Put Valvoline's Restore & Protect Oil in my Wife's Toyota, and The Results Shocked Me!
Image Source: Deposit Photos