The 5 Most Common Ford 3.5 Ecoboost Engine Problems

Honest Engine is reader-supported. This post contains affiliate links. As an Amazon Associate I earn from qualifying purchases.

Although it commands great respect among bullies on the road, the Ford 3.5L Ecoboost is not without its flaws. Even with its top-quality on-road delivery, reliability, low-cost maintenance, and increased efficiency, this engine features a few things that can make you feel on edge.

What are the most common 3.5 Ecoboost engine problems that you need to be on the lookout for? This simple guide has all the detailed answers to this important question.

Here are the five common issues:

  1. Failing Or Worn Timing Chain
  2. Bad Injection System
  3. Ignition And Spark Plug Defect
  4. Damaged Intercooler Or Intercooler Condensation
  5. Carbon Build-Up On The Intake Valve

These issues may not go away in a jiffy; yet, they have also not come to stay. Ford is committing aggressive efforts to upgrading and ensuring new models of cars powered by 3.5 Ecoboost engine don’t suffer the same fate like the previous ones.

What Are The Most Common Ford 3.5 Ecoboost Issues?

1. Failing Or Worn Timing Chain

A faulty timing chain is not uncommon to many of the first generation of Ford Ecoboost engines. If your Ford 3.5 twin-turbo V6 engine was not manufactured between 2010 and 2014, then you may not experience the timing chain problem.

Curiously, the F-150 V6 models are also victims of the overstretched timing chain. This issue involves the widening of the timing chain beyond its elastic limit. Parts of the timing chain that could be in trouble include the timing chain tensioners, cam phasers, or guides.

The timing chain is built to harmonize the rotation of the crankshaft and camshaft(s). When it slacks or wears out, the timing chain will cause the opening and closing of the valves to mistime.

The worn timing chain results mostly from damage to the tensioner and upper bolt of the chain. If you allow the problem to linger, it may cause the pistons to break or bend.

Symptoms Of Failed Timing Chain

The issue with a stretched or worn timing chain often gives off a few signs to indicate that this part of the engine is in great danger.

  • Rapid Noise At Idle: You may notice a rattling sound from the engine if your Ford 3.5 timing chain is defective or damaged. This quick-fire sound occurs when the engine idles.
  • Misfire Codes: A bad timing chain tensioner or guide also causes the check engine light to illuminate. The misfire code will indicate that something is not right with the engine.
  • Cold Start Rattling Noise: This occurs when your car engine is below the normal temperature to operate. Timing chain wear can cause the operating temperature of the vehicle to reduce. The other part is the noticeable rattling noise that accompanies whether the car starts or not.
    Usually, the Ford 3.5 Ecoboost will indicate the fault code P0016 to tell that something is wrong with your timing chain.

How To Fix Faulty Timing Chain

Let’s face it, fixing the timing chain comes at a cost and you should be prepared for it. The time it takes; the cost of purchasing the parts and the labor cost are things you should take by your stride when your vehicle’s timing chain breaks down.

The truth is that you may need to buy other minor parts plus the cost of replacing the main damaged part. The best bet is to replace the whole timing chain, and a mechanic would be in the best position to handle the issue.

2. Bad Injection System

Technicians and owners have complained about the severity of the effect of a bad fuel injector on the performance of the Ford 3.5L Ecoboost engine. This problem is specifically common among the first-generation models of this engine.

The new models are technically a combo of direct fuel injection and port injection systems. But then, a lot of those earlier models are still very much around the town and if yours is in the class, you should be wary of the fuel injection problem.

Generally, the injectors, fuel pump, and fuel filter constitute the under-the-hood components of the car. They’re essentially responsible for ensuring a proper air-to-fuel mixture ratio. The fuel injector receives gas from the fuel pump, and in turn, transfers it to the intake manifold.

Air and fuel mix inside the manifold before undergoing compression inside the combustion chamber. The result is the chemical reaction that gives off the power that ignites the engine. However, once the injection system goes bad, the engine will not function normally, causing some of it to give off some symptoms.

Symptoms Of Bad Injection System

  • Unpredictable RPM Gauge Movement: One of the noticeable signs of a bad fuel injection system is that the rpm needle will start to move without being prompted.
    Normally, the tachometer needle (vehicle’s rmp regulator) is supposed to move only when you engage or switching the gear; but a failed injection system will cause it to dance at will and move unpredictably.
  • Engine Misfire: Almost all problems associated with vehicle engines signal engine misfire. So, a clogged fuel injection system is not an exception. Once your fuel injector is dirty or there is an improper air-fuel mixture, your car may start to sputter or vibrate.
  • Rough Idle: Rough idle is often characterized by sputtering, shaking, stalling, and hesitation of your Ford 3.5L engine. Sometimes, the car will experience some vibration or that the engine is low on gasoline when going uphill.
    When this happens, you should consider cleaning the dirty fuel injector. Don’t forget, rough idle can also be caused by a few other issues.
  • Lousy Gas Mileage: Another symptom of failure in an injection system is the reduced fuel economy. You will notice that the gas mileage tanks, making you visit the gas station more often than normal. The peak of the issue is that you’ll notice lousy gas mileage which signals that your fuel injector is faulty.

How To Fix Failed Fuel Injection System

Fixing a failing or damaged fuel injection system requires some skill and techniques. The process is also complicated and expensive. The best shot for a car owner is to call a mechanic.

A technician will diagnose the problem to ascertain the root cause of the problem. A DIY approach may cause a shutdown of your engine and replacement will be the only option. Such a risk will amount to being penny wise, pound foolish.

3. Ignition And Spark Plugs Defect

The Ford 3.5L Ecoboost engine problems also manifest themselves in a defect in the ignition system and spark plugs. You’re most likely to have this issue if your vehicle is powered by a direct fuel injection system.

Don’t forget, the sparks plugs are an integral part of the ignition system and anything that affects the latter will affect the former.

The Ford 3.5L engine runs on a twin-turbo, making it also susceptible to ignition issues. In a way, the ignition coil problem is design-related but one that’s common to the most direct fuel injection system.

The ignition system is a victim of cylinder pressure that is coming from the turbos. This pressure wears down the ignition coil much faster, causing a premature shutdown of the entire system.

You’ll be pretty lucky to have your ignition coil last up to 25,000 miles before it breaks down. But the spark plugs spend fewer years than the coil.

Symptoms Of Failed Ignition System

So, if any of the components are damaged, there are a few other parts of the engine that will be affected, and the symptoms will come in form of engine misfires, stuttering, rough idle, and misfire codes.

  • Engine Misfire: Misfires accompany almost all the issues related to your vehicle engine. The kind of engine misfire caused by the defect in the ignition coils and spark plugs manifests in the condensation that happens in the intercooler. The engine will start to stumble intermittently. It may also misfire on high rpm and hard acceleration.
  • Misfire Codes: You’ll need to be on the lookout for misfire codes. As earlier noted, a defect in the spark plugs will cause a misfire code 4 (P0304). This code affects how your vehicle performs on the road and when it’s idle.
    Comes with specific misfire codes. You can also be on the lookout for misfires in cylinders 1, 2, and 3, with the following codes: P0301, P0302, and P0303, respectively.
  • Rough Idle: Rough idle will cause the car to shake or hesitate to work. After starting, the engine may rise and fall in rpm, causing unpleasant noise coming from inside it.

How To Fix Ignition Problem

The drivability of the vehicle is badly affected by the ignition problem and it is caused by the trapped water in the intercooler. The first thing is to determine whether the problem originates from a bad ignition coil or spark plugs.

To achieve this, you can test the ignition coils with another set of spark plugs. You can also do the same for the spark plugs. Having identified the sources, you can go all-out to start the fixing process.

Usually, the spark plugs are often the culprit because of their short life expectancy. Rather than replacing one and leaving the other, you’ll find it relatively cheap in the long run if you replace both the ignition coil and spark plugs at the same.

The good news is that the six plugs altogether won’t cost you more than between $50 and $100. You can go for the DIY method to replace the spark plugs. Within an hour or so, you should be done.

To buy the ignition coils, you’ll need to budget a little above $200, with the labor cost coming in the region of $100 or less. But you may not necessarily need a mechanic to replace the coil.

4. Damaged Intercooler Or Intercooler Condensation

Intercooler condensation is one of the visible common problems of the Ford 3.5 Ecoboost engine. This problem raises its ugly head mostly during the high humidity, rainy seasons, or damp conditions.

You’ll notice that some water from the road or oil can always find its way into the intercooler system, causing low acceleration or engine misfire. The water will condense inside the intercooler system.

The Ford manufacturer has tried to rectify this problem by changing the position of the air deflector to the bottom of the intercooler from the top.

The idea behind this is to ensure that the air deflector can vaporize the moisture and condensation that forms. However, this problem still pops up from time to time in the Ford 3.5 Ecoboost engine upgrades.

Symptoms Of Damaged Or Leaking Intercooler

  • Drop In Engine Power: This is a major sign that may tell you the intercooler of your 3.5 Ecoboost engine is either leaking or damaged. The vehicle will not work as efficiently as it should.
  • Increased Fuel Consumption: If you notice that you often visit the gas station than normal, a damaged 3.5 Ecoboost intercooler may be responsible. In this case, the car will use more than normal gas.
  • Smoke From The Exhaust System: You may also suspect the intercooler if you notice excessive smoke coming from the exhaust system.
  • Overheating: When your intercooler is clogged, you will the temperature gauge on your dash rise. This is a sign that your car is overheating.

How To Fix Intercooler Condensation

There are two methods to get rid of the intercooler condensation. Ford’s repositioning of the air deflector has helped in a way but with the advancement of engineering, drilling a hole in the intercooler and installing a catch can have proven effective over the years.

To cure the intercooler condensation in your 3.5 Ecoboost engine is by drilling a hole in the intercooler inlet. The 1/16” hole is considered effective because it lets oil or water escape before it causes an engine misfire.

The only downside of the solution is that it may cause oil or water leaks. Overall, it is cheap and less cumbersome to perform.

The second solution is by installing a catch can in the intercooler. The process is simple and doesn’t require any special skill or technique. Simply redirect the vacuum lines to pass through the catch can.

While this is happening, may sure you pull back the vacuum from the turbo inlet. But you must be ready to drain as much water or oil that gets into the catch can as frequently as possible (maybe about every 3000 miles).

5. Carbon Build-Up On The Intake Valve

The truth is that carbon build-up is a major issue common to most of Ford’s first-generation engines. This is because these models are made only as direct fuel injection systems. The brand has made a lot of improvements in the upgrades, including the 2nd and 3rd-generation Ford 3.5L Ecoboost engine.

Especially, with the combination of port injection and direct fuel injection, the Ford 3.5 engine valve-bound carbon build-up problem has largely subsided over the years.

The impurities and oil deposits in the fuel getting into the combustion chamber are washed off through the intake ports and valves. Yet, even with the new models, you cannot rule out the concern completely.

The carbon accumulation on the intake valves needs urgent attention. This is because oil deposits often clog the free flow of air into the cylinder, causing the engine to misfire. Other issues such as drivability and power loss can occur.

Symptoms Of Carbon Build-Up

Some signs accompany carbon accumulation in your car’s intake manifold and cylinders.

  • Engine Misfire: Do not panic when you hear engine misfire. The majority -if not all of the mechanical and/or electrical problems in your car problems cause the engine to misfire. Carbon build-up is not an exception. When your car engine misfires, it shows some stuttering or hesitant disposition to idle.
  • Power Loss: No doubt, the carbon build-up can cause the engine to lose power. It won’t start because a restriction has been placed on airflow by the vast amount of carbon deposits that have been accumulated on the intake valve. You will notice a visible lack or loss of power and reduced fuel efficiency.
  • Rough Idle: Have you once started your car and you receive some kind of irritating response from the engine? You’ll the engine running lean. In addition, you may also notice fluctuating performance due to the inability of fuel to get to its destination. When these happen, the first thing to suspect is carbon build-up.
  • Low Acceleration: Sometimes once there is carbon build-up on the intake valves, you may notice that the acceleration of the car doesn’t match the rpm when you step on the throttle or gas pedal.

How To Fix Carbon Build-Up

As soon as you start to observe the symptoms itemized above, you should begin to take decisive steps to tackle the issues from the root. Carbon accumulation in car engines is traditionally dealt with by Walnut blasting.

This method has proved to be extremely effective in getting rid of fuel deposits that bypass the intake valves and cylinder into the combustion chamber.

What materials and tools do you need? Carrying out a walnut blasting procedure requires a shop vac and a few walnut media shells. You’ll also need a few other tools but what is most important is to be faithful to the procedure. It is pretty seamless and simple.

Alternatively, and this will interest you better, you should try as much as you can to prevent carbon deposits from building up in the intake valves and cylinders. You cannot be too extra careful.

Here are ways you can prevent that build-up:

  • Take your vehicle for scheduled servicing and maintenance.
  • Replace the ignition and spark plugs as and when due. Doing this will reduce and take the amount of unburned gas deposit off the combustion chamber.
  • Make sure oil change is in accordance and within recommended intervals.
  • Apply recommended oil, fuel cleaner, and fuel.

Overall, ensure that your engine has reached the required mileage before of between 80,000 and 100,000.


1. Can I Rely On Ford 3.5 Ecoboost To Power My Vehicle?

Yes. Without sounding too immodest, the reliability issue is not one of the things you’ll successfully pick against the Ford 3.5 Ecoboost engine. This engine ranks high among the majority of the engines designed by the brand due to a lot of reasons.

The first-generation models of Ford 3.5 may have their issues but since the upgrade that began with the second-generation models, a lot of work has gone into redesigning and re-packaging of the entire system.

The Ford 3.5 Ecoboost engine problems identified above are not issues that are exclusive to this model alone. Most engines that run on a direct fuel injection system also face the risk of being categorized into the fray. Don’t forget, reliability also depends on how you use and maintain the engine.

Typically, the Ecoboost 3.5 V6 is built to last at least 150,000 miles. Guess what? This mileage can extend to 250,000 if all precautions are taken, including pre-purchase inspection and post-purchase maintenance.

However, your 3.5 Ecoboost engine may not reach its expectancy before it packs up if you don’t take scheduled servicing seriously. Changing the oil at recommended intervals; using recommended gas, and attending to any symptoms on time are ways to prolong the life of the engine.

2. How Can Make My Ford 3.5 Ecoboost Engine Last Longer?

The best way to keep your 3.5 Ecoboost engine in good shape is to ensure regular maintenance. Topping the oil and changing as and when due is critical to prolonging the life of your vehicle. Use recommended oil: synthetic oil has proven to be the best.

Final Thoughts

The 3.5L Ecoboost engine has been around since 2010. With a lot of upgrades carried out on most of the engines manufactured by the Ford brand, some of the most common 3.5L Ecoboost engine problems are not apparent or characteristic of the second, third, and latest generations.

The 3.5 Ecoboost engine is a top-quality engine, but you shouldn’t leave anything to chance when you’re making an order for this motor.

Sometimes, even the best engines can come out not meeting specs and expectations. Take pre-purchase precautions seriously and carry out a proper inspection when buying any car parts.