4 Most Common Ford 3.5 EcoBoost Engine Problems & Reliability (2024)

Ford 3.5 EcoBoost engines came out in 2010 in the Lincoln MKS, MKT, Ford Flex and Taurus SHO. The 3.5 liter twin turbo V6 then made its way into many other Ford and Lincoln models in the following years. It’s a stout engine offering 355 to 647 horsepower and plenty of torque. Turbocharging and direct injection also help the 3.5 V6 remain fuel efficient and cleaner on emissions. Overall, the 3.5 EcoBoost is a great engine but no engine is perfect and that applies here. In this article, I discuss Ford 3.5 EcoBoost engine problems and reliability.

Ford 3.5 Twin Turbo V6 Background

Before diving into 3.5 EcoBoost problems it’s important to lay out a little background info. There are two different generations of the 3.5 EB, which we will discuss quickly below. It’s important to lay this out for a reason. Ford did a solid job with some updates in the 2nd gen 3.5 EcoBoost engine. The updates help support extra power and torque. They also address a few reliability concerns to make the 2nd gen Ford 3.5 twin turbo engine even more reliable.

1st Gen Engine

The above isn’t to say the 1st gen is a bad engine by any means. However, combining turbos, direct injection, and VVT was a new direction for Ford. There are always a few kinks to work out, and for the 3.5 V6 they were pretty minor. We’ll be diving into this in the upcoming discussion on common 3.5L EcoBoost engine problems.

Anyways, the 1st gen EcoBoost makes 355-380 depending on the specific vehicle. The smaller twin turbos are quick to spool and provide tons of low-end and mid-range torque. It makes the 3.5 EB a great engine for towing and fun around town without having to use all of the RPM’s. The 1st gen 3.5 EcoBoost is found in the following Ford and Lincoln models:

• 2010-2019 Ford Flex
• 2010-2016 Lincoln MKS
• 2010-2019 Lincoln MKT
• 2010-2019 Ford Taurus SHO
• 2013-2019 Ford Explorer Sport & Platinum
• 2011-2016 Ford F-150
• 2015-2017 Ford Expedition
• 2015-2017 Lincoln Navigator

2nd Gen EcoBoost

In 2017, Ford began rolling out the 2nd gen EcoBoost in some models. It sees a bump to 375-450 horsepower in most models. However, Ford went a step further with a 647hp variant for the legendary Ford GT. That engine, of course, receives some upgrades over the standard 3.5 EcoBoost to support the power.

Ford also introduced port-injection on the 2nd gen 3.5 V6 twin turbo engines. This helps prevent against carbon build-up, which we’ll be discussing in this article. Additionally, Ford re-designed the timing chain due to some reliability concerns with the previous design. Another thing we’ll be diving into. The 2nd gen engine is in the following models:

• 2017-present Ford F-150
• 2018-present Ford Expedition
• 2017-present Ford F-150 Raptor
• 2018-present Lincoln Navigator
• 2017-present Ford GT

If you would rather consume this content via a video, check out our Ford 3.5 EcoBoost Common Problems video below:

4 Common 3.5 EcoBoost Problems

With some of the background info out of the way let’s move onto the actual subject at hand. A few of the most common issues with the Ford 3.5 EcoBoost engine include:

• Carbon Build-up
• Timing Chain
• Cam Phasers
• Ignition System

As we sort of mentioned above, the top two problems mostly affect the 1st gen 3.5 EcoBoost engine. Ford did a great job at updating some of the weaker points with the 2nd gen engine. Again, the 3.5 EcoBoost really is a solid, reliable engine overall. Two of the “problems” we list above might not even be fair to call problems. Carbon build-up is simply a downside to using direct injection alone. The ignition system parts like spark plugs and ignition coils are also simply a downside to turbocharging.

That said, we’ll dive into these 3.5 EcoBoost problems in greater depth below. Let’s knock out a few quick notes before. Just because we’re classifying these problems as common does not necessarily mean they affect a large percent of 3.5 V6 engines. Rather, they’re a few of the most common issues when something goes wrong. Additionally, engines are prone to many other problems we’re not discussing – especially with age and mileage.

1) Intake Valve Carbon Build-Up

Carbon build-up is primarily a concern on the 1st gen engines. The 1st gen 3.5 EcoBoost only uses direct injection (DI), which means fuel is sprayed directly into the cylinders. As such, carbon build-up on the intake valves occurs over time. All engines experience some degree of oil blow-by. This oil makes its way through the intake tract where it eventually cakes onto the intake valves. Port injection has the benefit of fuel washing over the intake ports and valves. That helps wipe off the oil deposits and prevent it from accumulating.

However, when you only have DI fueling there is nothing to help clean the ports and valves. Over time, carbon deposits build-up and restrict air-flow into the cylinders. It’s not a major issue that requires immediate attention. Some DI engines even go their whole lives without having any valve cleaning. However, carbon build-up can result in power loss and plenty of other drivability issues.

With the 2nd gen 3.5 EcoBoost, Ford reduced this issue by utilizing both direct and port injection. It’s the best of both worlds in many ways since DI has many benefits over PI. However, using PI has a few benefits of its own – especially helping prevent against carbon build-up.

Carbon Build-Up Symptoms

Symptoms of excess carbon build-up on the 3.5 EcoBoost intake valves and ports include:

• Misfires
• Rough idle
• Stuttering / hesitation
• Power loss

Most of these symptoms are a by-product of the first symptom at hand – misfires. The carbon deposits can cause un-even amounts of air to enter to cylinders. This throws off the air-fuel mix and may cause the 3.5 EB to misfire. That can in turn cause symptoms like fault codes, rough idle, and stuttering. Power loss is another common symptom of carbon build-up on the Ford 3.5L turbo engine. However, it’s often hard to detect since carbon build-up occurs over a long period of time. Chances are you won’t notice power loss that occurs slowly over a several year period.

3.5 EcoBoost Carbon Build-up Fix

Once the carbon deposits become excessive then you’ll want to consider walnut blasting the intake ports. The job requires a quality shop vac and walnut media shells. Otherwise, it’s mostly just the labor in accessing the intake ports. Shops often charge $400-600+ for this job, so it’s not exactly cheap.

Fortunately, it’s not an urgent item that needs to be done quickly and you may not even want to do it at all. Carbon deposits shouldn’t cause any serious longevity concerns for the 3.5 EcoBoost. We would still want to take care of the job, regardless. Expect walnut blasting to be good maintenance to complete every 70,000 to 100,000 miles.

2) Timing Chain Problems

Specific details on the Ford 3.5 timing chain problems are hard to come by. This issue mostly affects the 1st gen engines. More specifically, it seems to primarily affect 3.5 EcoBoost engines from 2010-2014. Ford improved the part prior to re-designing it for the 2nd gen 3.5L twin turbo V6. Timing chain issues also appear to mostly affect the F-150 models more than any other. Though, it’s very possible that’s simply due to the fact the F-150 is the most popular model using the EcoBoost engine.

Anyway, the issue at hand involves stretching of the timing chain. Some problems also occur with the 3.5 EcoBoost timing chain guides, tensioner, and cam phasers. It’s a good idea to replace the entire timing chain assembly if an issue does pop up. Fortunately, Ford did issue a service bulletin for these problems. If you’re out of warranty and run into timing chain problems you may be able to work with Ford.

These problems are typically urgent and should be repaired as soon as possible. If timing chain completely fail it’s possible for additional damage to occur to the 3.5 EcoBoost engines. It’s a very rare occurrence, but it’s important to repair the timing chain in a timely manner if issues pop up. We also have a complete guide on 3.5 EcoBoost timing chain problems.

Timing Chain Symptoms

• Cold start rattle
• DTC P0016
• Check engine light
• Drivability issues

Rattling on cold starts is one of the more common symptoms that may indicate something is going on with the timing chain. Plenty of other things can cause rattle, though. Also, look for the 3.5 EcoBoost to throw the P0016 fault code which will also trigger a check engine light. Finally, once the timing chain stretches it can throw ignition timing off and cause drivability issues. This includes misfires, power loss, rough idle, etc.

Timing Chain Replacement

Replacing the timing chain and other components isn’t an easy or cheap job. It’s labor intensive and the part costs can add up. You may also consider replacing some other small items while in there. Expect timing chain replacement to add up into the thousand plus dollar ballpark.

However, many faulty 3.5 EcoBoost timing chains were likely replaced at some point. It’s a common problem on the EcoBoost, but not every engine runs into these issues. Some suspect it comes down to poor maintenance and oil change history or using 20w oils, which are too thin for the engine. Ford also issued bulletins so they’re well aware of the timing chain problems. Even if it’s not covered under warranty you may be able to work with Ford for discounts or alternative compensation.

3) Cam Phaser Issues

Next on the list of Ford 3.5 EcoBoost problems is the dreaded cam phaser rattle. This primarily affects the 2nd generation 3.5L V6 from 2017-2020. The 2nd gen engine addressed the timing chain problems, but that introduced an issue with the cam phasers. Fortunately, Ford finally fixed the cam phaser issues in 2020.

The bad news is that cam phaser issues are very common, and likely the single most common 3.5 EcoBoost problem on this list. At least for the 2017-2020 models that suffer from cam phasers the most. Ford did issue Customer Satisfaction Program 21N03, which essentially offers an extended warranty on cam phasers until January 1, 2023. However, only a portion of the cost (or even none) is covered by Ford depending on exact mileage.

The good news is 3.5 EcoBoost cam phaser problems do not affect performance or safety. As such, the 3.5L V6 cam phasers don’t absolutely need to be fixed. However, the rattle can certainly be annoying and embarrassing. It’s also best to replace the VCT phasers to avoid any other reliability concerns or problems down the road.

If you want to learn more about 3.5L EcoBoost cam phaser rattle, we’ve written an entire article about the subject.

VCT Phaser Symptoms

Symptoms of 3.5 EcoBoost cam phaser problems include:

• Cold start rattle
• Engine shuddering

The main symptom of cam phaser problems is simply rattling. It’s most common on cold starts but some also experience rattling during acceleration. In the worst cases, the rattle may be constantly present. Ford initially tried reprogramming the PCM to reduce the cam phaser rattle, per Customer Satisfaction Program 21B10.

However, the reprogramming was known to then cause engine shuddering so Ford issued 21N08. This program simply had dealers change the 3.5 EcoBoost back to its original programming to get rid of the shuddering. Ultimately, engine shuddering is another possible symptom of 3.5 EcoBoost cam phaser problems.

3.5 EcoBoost Cam Phaser Replacement

Hopefully your 3.5 EcoBoost falls within the extended warranty parameters. In this case, Ford will cover all or part of the repair cost to fix the cam phasers. If you’re outside of the warranty then it’s still a good idea to call Ford corporate; they may still provide some help even if the EcoBoost is out of the cam phaser extended warranty.

If that doesn’t work then you’ll unfortunately be paying for the cam phaser replacement out of pocket. It’s a labor-intensive job so it’s also a good idea to replace other parts in the area. We recommend replacing the timing chain, tensioner, guides, seals, gaskets, and all four cam phasers. The full job will likely run about $2,000 to $3,000 at a repair shop.

4) Spark Plugs & Ignition Coils

Well, this is mostly here because we’re out of other 3.5 EcoBoost problems. Calling spark plugs and ignition coils an “issue” likely isn’t fair. However, it’s part of the nature in owning a twin turbo, direct injected engine. Coming from the BMW world we’re very familiar with this. Turbos put a lot of stress on the ignition system in part due to the incredibly high cylinder pressures.

Spark plugs often last 70,000+ miles on naturally aspirated engines and ignition coils usually last about double that. However, with the 3.5 twin turbo EcoBoost engine the ignition components will likely wear down much faster. It’s often just standard wear and tear, but premature problems are possible. This is pretty simple stuff on any engine and the 3.5L V6 from Ford is no exception.

Ignition components can cause a plethora of symptoms and other drivability problems so don’t overlook simple spark plugs or coils. Stock 3.5 EcoBoost engines will likely require new spark plugs every 40,000 to 60,000 miles. Expect the ignition coils to last about twice as long. If you’re running a tune, mods, or driving the 3.5 EcoBoost hard then the lifespan of ignition parts can shorten drastically. Our modded twin turbo 335i with the N54 engine requires new spark plugs every 10,000 miles. Ignition coils make it to the 25,000 mile mark – if we’re lucky.

Spark Plug & Ignition Coil Symptoms

• Misfires
• Rough idle
• Stuttering
• Check engine light (misfire codes)

Plugs and coils usually exhibit these same symptoms. We typically recommend replacing all 6 spark plugs or ignition coils at the same time; especially if it’s been a while since they were changed. If you’re experiencing misfires here’s an easy way to see if a spark plug or coil is to blame. Check the fault codes to determine which cylinder(s) is misfiring. Pull the ignition coil from that cylinder and swap it with a cylinder that is NOT misfiring. If the misfire follows to the new cylinder then you’ve located your issue.

If it does not follow you can try the same with the 3.5 EcoBoost spark plugs. You may also just consider replacing the spark plugs anyways. It’s a cheap and easy repair.

Plugs & Coils Replacement

Again, the above method is a good way to determine where the issue is originating. Often it’s the spark plugs to blame since their life is a lot shorter than ignition coils. Fortunately, a set of 6 Ford 3.5 spark plugs usually comes in around $40-100 depending on where you source the parts. It’s an easy job that nearly anyone can accomplish in the driveway in less than an hour or two.

A set of ignition coils is a bit pricier at $200-300. However, it’s an even easier job than the spark plugs. Knock this out on your own or if you prefer a repair shop labor should come in under $100.

Ford 3.5 EcoBoost Reliability

Is the Ford 3.5 EcoBoost engine reliable? Yes. We believe the Ford 3.5 twin turbo engine receives above average remarks for reliability. There aren’t too many common issues that pop up on these engines. Additionally, Ford did a great job at addressing some of the problem areas with the 2nd gen 3.5 EcoBoost.

Of course, how reliable each 3.5 V6 engine is comes down to the luck of the draw in some cases. It’s one of the factors we don’t have control over. However, you can control how well you maintain the twin turbo EcoBoost engine. Change the oil on time, use quality oils, and fix problems in a timely manner if they pop up.

Take care of the 3.5 EcoBoost and it will likely reward you with a great, reliable experience. Turbo engines do add a bit of extra maintenance, but we think it’s rewarding in the end. Ford EcoBoost engines offer excellent power, torque, fuel efficiency, and towing capability. Most 3.5L V6 EcoBoost engines shouldn’t have any major issues making it to 200,000 miles or beyond. Not too bad for longevity.

3.5 EcoBoost Common Problems Summary

Not to disrespect the Ford 5.0 Coyote engine, but we believe the 3.5 EcoBoost is the clear choice if you have the option. The Ford 3.5 EB offers such a great balance of power, torque, towing, efficiency, etc. Use of twin turbos also allows for tons of tuning potential for those who want even more out of their engines. We really like the 3.5 EcoBoost, but no engine is perfect.

Earlier gen 1 engines run into some problems with timing chain failure and carbon build-up. Timing chain issues likely aren’t as common as some may lead you to believe, but it’s something potential owners should be aware of. Direct injection also naturally leads to carbon deposits on the intake valves that can cause drivability issues. Ford did a great job at addressing these problems once they realized the issues.

Otherwise, it’s important to keep in mind that turbo engines can be a little more demanding on maintenance. Spark plugs and ignition coils take a lot of abuse due to the turbo boost pressures. Turbo engines like the Ford 3.5 EcoBoost also have more parts to potentially fail. Nonetheless, turbo technology has come a long way in the past decades. Maintain the Ford EcoBoost engine well and it will likely reward you with a reliable, fun experience.

What’s your experience with 3.5 EcoBoost problems? Drop a comment and let us know!

Looking for more info? Check out our complete 3.5 EcoBoost engine guide or 3.5 EB vs 5.0 Coyote.

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