Cylinder #6 misfire on 4.0 liter SOHC

I've replaced EGR plugs wires TPS idle control valve coil MAF sensor still show #6 misfire starts and runs but had vibration at 55 mph do u have an idea what this could be and has been wrong with similar vehicles cost to fix? Thanks Dan.

My car has 212000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hello. Good job on getting the basic tune-up work done! Given the mileage, this engine may have a longer-term issue, namely, accumulated wear on piston rings or a blown head gasket. Both of these can be diagnosed with a compression test, or a leak-down test if compression numbers are more consistent than engine running suggests. If the miss is constant and regular, a burned valve is also a good possibility. I recommend having a professional, such as one from YourMechanic, inspect the misfiring issue in person to diagnose this problem and assist with repairs.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Cylinder 4 misfires can be caused by many reasons from a faulty ignition system, fuel system, or internal engine failure. The most common reason for this to happen is faulty or worn-out spark plug coil packs, especially if it`s been a while since you had a tune-up.
Major Factors that Lead to a Misfiring

The most typical cause of this is faulty or worn-out spark plug coil packs. It happens if you haven`t had a tune-up in a while. Cracks- Insulation cracks or fouling may prevent the defective spark plug from effectively firing in cylinder 6.

A misfiring cylinder can cause the engine to run excessively rich and can damage the catalyst. The misfire will cause the engine to run rough and hesitate on acceleration. The engine will use more fuel due to the misfire.
Engine misfires happen when one of the cylinders does not produce sufficient spark or compression and lack of fuel. It could involve more than one cylinder. It can be caused by a faulty spark plug, fuel injector, ignition coil and or worn cylinder.
A clogged or failed exhaust gas recirculation or crankcase ventilation valve or faulty oxygen sensor can send the wrong signals to the computer and cause misfires.
The most common causes of misfires are worn, improperly installed, and mishandled spark plugs, malfunctioning ignition coils, carbon tracking, faulty spark plug wires and vacuum leaks.
Symptoms. The signs of a leaking turbocharger system start with a lack of power or random misfires.
It could be due to a part that`s failing in your fuel system. If an oxygen sensor or mass airflow sensor is failing, it could give incorrect data to your engine`s computer, causing the misfire.
An engine misfire can be caused by bad spark plugs or imbalanced air/fuel mixture. Driving with a misfire isn`t safe and can damage your engine.
Vacuum leaks, especially those that are confined to one cylinder, will cause the engine to idle unevenly and possibly misfire. This is because the vacuum leak allows additional air to reach the affected cylinder, diluting its air/fuel mixture.
A faulty spark plug or ignition coil is one of the primary reasons why a car misfires at idle. Other potential causes include vacuum leaks, faulty fuel injectors, malfunctioning air control valves, and low compression.
Yes. While the damage may seem small initially, the longer you drive with a bad oxygen sensor, the worse the damage will become. Eventually, you may experience rough idling, poor acceleration, engine misfires, an illuminated check engine light, and failed emission tests.
A bad oxygen sensor, mass air flow sensor, manifold pressure sensor, throttle position sensor, a stuck-open exhaust gas recirculation (EGR) valve or an engine vacuum leak can cause a lean running engine, which can cause a backfire.
The type “A” misfire is the most serious condition and indicates impending catalyst damage. If detected, the Malfunction Indicator Lamp (MIL) may flash once per second to alert the driver that immediate service is required.
However, most misfires dissipate, and your engine regains its normal speed after a second or two. But even a single misfire is usually a sign that something else is wrong and that more misfires will likely occur in the future.
Repairing or replacing a cylinder can range from $100 to $1,000. Different causes for misfires cause different severities of damage that each cost varying amounts to repair. These damages are: Slower fuel delivery issues can cost anywhere from $200 to $1,000.
If left untreated, a cylinder misfire can lead to significant engine damage. Worse, if you experience a bad misfire while driving, it could result in an accident. This is why it`s important to treat engine misfires as soon as you detect them.
An engine misfire can be caused by bad spark plugs or imbalanced air/fuel mixture. Driving with a misfire isn`t safe and can damage your engine.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Code said cylinder 1 misfire, cylinder 2 misfire, o2 sensor misfire?
ANSWER : Without checking the ignition coils and spark plugs myself for proper spark output I would say the engine is misfiring and may be the coils and plugs. It is also common for the valve cover gasket to leak oil into the spark plug tubes shorting the coil and spark plug out so it cannot fire. The check engine light is flashing due to the misfire is active and additional catalyst damage can happen if you keep driving with the misfire and raw fuel dumping into the catalyst. I would recommend having a mobile mechanic like one from YourMechanic come and do a through diagnosis to see if the valve gasket is leaking into the spark plugs and caused damage to the coils and spark plugs. If it is leaking then the valve cover gasket should be replaced with the spark plugs and contaminated ignition coils replaced then computer codes an be cleared and the vehicle road tested for any other problems from driving the vehicle with the engine misfiring.

Jeep takes has trouble starting initially and now has a cylinder 6 misfire
ANSWER : The misfire could be caused by a lack of fuel pressure. Cylinder 6 is usually the last cylinder to be fed by the fuel rail, and when the pressure is low, it can suffer from a lack of fuel. But, there are several other possible causes for a cylinder misfire. I would suggest having a certified mechanic, like those available at YourMechanic, take a look at the vehicle, and diagnose what is causing the misfire.

Keep getting multiple misfire codes, normally different cylinders except on cylinder (0307), can this one be throwing off the rest
ANSWER : This may be a problem with the exhaust catalyst partly clogged causing excessive back pressure. There is a test where the O2 sensor is removed and the back pressure tester is put in the hole to see if the catalyst is clogged.

The computer should be scanned to see if you are running lean from bad O2 sensors or for some other reason. The coil may also be weak and not putting out enough spark energy. Have the system checked by a mechanic since this truck engine may have exhaust problems, engine carbon build up, cracked valve seats, O2 sensor problems, coil problems, camshaft and distributor cam gear worn problems. The list goes on and will require a qualified mechanic time to diagnose this complaint for you. If a shop or mechanic cannot figure it out then it may take a factory trained mechanic to be able to diagnose the problem down to one of the listed issues. The best thing to recommend is to replace all the tune up items first so these can be eliminated. This means coils, plugs, wires, fuel filter and air filter, and PCV valve.

Hi James, engine lite on, cylinder misfire on 1, 3, 5, and 6. recently replaced all plugs and wires. question is does it do any go
ANSWER : Hi there. What led you to the need to replace those mentioned parts? What were the diagnostic steps to determine the fault or faults? When a misfire code is stored, that means that the ECM detected a slow down on the combustion stroke of those cylinders specific to the codes stored. What caused the misfire? The ECM does not know why this occurred, only that it has detected the occurrence. There could be a whole host of causes from electrical to fuel to spark to a sensor to the ECM to an internal mechanical fault. The simple fact is that without a proper inspection using proper diagnostic tools and processes, the attempted repairs can become very expensive. I strongly suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a check engine light inspection.

Misfire on cylinder one
ANSWER : A misfire to cylinder 1 may be a fuel pressure regulator sensor problem but it is most likely due to a clogged injector on number one. You will need to scan and view data to see if fuel pressure sensor is needing replacement first. Then have the injectors cleansed to see if the codes go away.

I’d suggest you get this looked at by a qualified technician who can perform these checks to diagnose your Check Engine Light and make the appropriate repairs to your vehicle.

What would cause 1st cylinder misfire, multiple misfire, all fuel injectors circuits open and o2 sensors heater circuit high on a 2008 Dodge Charger
ANSWER : Hello. It sounds like you may have the wrong parts installed on the car. Due to the fact that multiple people have worked on it you may have some parts that do not meet specifications. From what it sounds like to me though you either do not have an ECM in the vehicle with the correct programming or you have a connection issue. If all of the grounds are not clean and tight then that will cause this. if they are then the computer needs to be programmed to your vehicle at the dealer and that may take care of it.

#6 cylinder misfire. 1999 Ford Explorer
ANSWER : Hi there – unfortunately, pulling the plug on cylinder 6 is necessary for the next level of misfire diagnosis: is there actually spark at the plug while running? What is the compression on that cylinder (and any other – are they within 10% of each other)? Is that plug brown or black, or wet with fuel – signifying a leaking injector? You can get to a precise answer, but it will require a bit more effort. I would recommend an engine misfire inspection](https://www.yourmechanic.com/services/engine-is-misfiring-inspection) by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

Cylinder #6 misfire on 4.0 liter SOHC
ANSWER : Hello. Good job on getting the basic tune-up work done! Given the mileage, this engine may have a longer-term issue, namely, accumulated wear on piston rings or a blown head gasket. Both of these can be diagnosed with a compression test, or a leak-down test if compression numbers are more consistent than engine running suggests. If the miss is constant and regular, a burned valve is also a good possibility. I recommend having a professional, such as one from YourMechanic, inspect the misfiring issue in person to diagnose this problem and assist with repairs.