Timing off or plugs need replacing

My car is running rough. I think either the timing is off or the spark plugs need replacing.
Experienced mechanics share their insights in answering this question :
Hello. The timing on your vehicle is not adjustable and should not be a problem. Most of the time this is caused by worn out spark plugs or a sensor that is not reading correctly. I would typically start by scanning the computer for codes to see if the computer is seeing any faults. Using the right scan tool will also allow me to see the sensor readings to see if any of the sensors are not reading right. It may also be dirty fuel injectors. If you are planning on having this diagnosed, consider YourMechanic, as a certified mechanic can come to your home or office to determine why your car is running rough.

How to Identify and Fix Common car Problems ?

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Consequences of Incorrect Spark Plug Gap

If the spark plug gap is incorrectly set, it can lead to engine issues. The customer may experience loss of power, misfires, spark plug fouling, increased plug wear, or poor gas mileage.

Absolutely yes, a loose spark plug will cause issues like compression leak, poor combustion, misfire. all these will result in rough idle. Can bad spark plugs cause rough idle? Yes, but they`d cause problems at higher rpms, too.
If your Spark Plugs are failing your engine will sound rough and jittery when running at idle. This can cause vibrations to resonate through the vehicle which could cause further costly damage.
Rough starts, hesitation and poor acceleration are all common symptoms of a bad spark plug. If a spark plug or multiple spark plugs are faulty, they will have trouble creating the spark that causes the ignition process in your vehicle.
For most racing applications, you usually want the plug gap to be between 0.020 and 0.040 of an inch. Most engine builders seem to settle around 0.035 of an inch. Factors such as the type of ignition you run, cylinder heads, fuel and even timing can affect how much gap will work best for you.
Changing the spark plug gap won`t affect the ignition timing, but it will have some affects on the ability of the spark plug to ignite the fuel.
Engine Misfires

Perhaps the single most common cause of rough idle comes in the form of a misfiring engine. As you may know, any automotive engine contains multiple cylinders. Each of these cylinders contributes to powering your car by combusting a mixture of gasoline and air.

A rough idling engine can be caused by spark plugs or spark plug wires. Spark plugs use the electrical current received from ignition coils to ignite the air/fuel mixture within the combustion chamber. A plug that is damaged or installed incorrectly can result in fuel being burned at an inconsistent rate.
Oxygen (O2) sensor

An oxygen sensor monitors and analyzes the amount of oxygen in a vehicle`s exhaust system after combustion. A dirty, damaged or malfunctioning O2 sensor (or sensors) affects the air/fuel mixture, causing the engine to idle rough.

Generally, the cause of a misfire at idle is an incorrect air-fuel mixture. This can be caused by a faulty O2 sensor, a fuel injector that needs cleaning, or even vacuum leaks.
It`s not normal for your car to shake after a spark plug change. There is a possible misfire caused by one of the coils not being seated properly. The problem may also be due to a non-sparking plug or misrouted ignition leads in the connection. Also, check for possible plug wires swap and the firing order.
After you`ve changed your spark plugs, you should start up your engine to make sure they`re working as they should. If your engine starts up without a hitch, you can pat yourself on the back for a job done right.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Need to replace bad spark plug & coil pack on Ford Expedition but not sure what else I need besides the plug and coil pack?
ANSWER : Hi There,
I would recommend having an expert from YourMechanic come to your location to take a look at the vehicle to first determine what the cause of the misfire is if this has not already been done. Engine misfires can be caused by many different problems and are generally caused by either a spark or fuel issue or in some cases, a combination of both. Spark related problems generally will result from things like ignition coils, crankshaft position sensor, spark plugs, spark plug wires or ignition modules not working properly. When the misfire results from a fuel related issue, this is commonly related to a lean fuel condition (lack of sufficient fuel supply to the motor). Fuel related misfires can be caused by many different things such as low fuel pressure, faulty or dirty fuel injectors, a faulty O2 sensor, a dirty or failing mass air-flow sensor, a faulty or dirty idle air control valve or a vacuum or intake leak. When the fuel supplied to the combustion chamber is insufficient, this results in an ignition (spark) that is igniting a less than balanced load of fuel and air. This results in a misfire or an explosion in the cylinder that is much less powerful than the other cylinders. This creates a loss of power that resonates throughout the motor additionally causing other problems with ignition and fuel timing. Due to the number of different things that may cause an engine misfire, the quickest and easiest way to diagnose this type of problem is to hook the vehicle up to a scanning tool which will download any potential fault codes that may have registered in the vehicle’s computer as a result of the poor running condition. I would recommend having an expert from YourMechanic come to your location to diagnose your misfiring problem.

Do I need to replace timing belt again of replacing water pump?
ANSWER : The water pump and timing belt should be replaced as a set if the coolant leaked on the belt. The coolant leaking on it will damage the belt.

How do you know if the ignition needs to be replaced when you replace the plugs on dodge 5.7 hemi?
ANSWER : Hi there. To determine if the ignition coils need to be replaced, remove one park plug wire at a time and hook it up to a spark tester gauge and set the gauge to 10 thousands gap and increase it to 60 thousands gap. If the spark does not appear after 25 thousands gap, then the coil is too weak and needs replaced. If you need further assistance with your ignition coils, then seek out a professional, such as one from Your Mechanic, to help you.

Do i need to replace the receiver drier and/or the expansion valve when replacing the condenser assembly?
ANSWER : Replacing the system drier is absolutely essential. If the system has been open to the atmosphere (due to the leak in the condenser), the desiccant in the drier has been fully saturated with moisture. As far as the expansion valve, replacement is not normally implicated in a leak repair, in your case a leak in the condenser. To justify replacing the expansion valve, there would have to have been a diagnostic performed which proved a fault. If no diagnostic was performed, and there is no evidence of a fault, then it is pointless to replace the valve. But, again, drier replacement is absolutely essential. To add the drier to your order, you can simply add a note to the mechanic in your order and/or add it as a service (you will see a link that you can click on to "add services" or write in specific services). If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Plug broken. Safe for replacement? Pins are different
ANSWER : Although, I am not an electronics expert by any means, there are some basic electricity concepts that should apply in this case. First we need to identify what the ratings on the plug pertain to:

Amp – an ampere is the unit for measuring electricity. The accepted standard unit used for measuring how fast an electric current flows.

Volts – Electrical pressure is measured in Volts. How difficult it is to move electrons through a circuit is called resistance. Electrical resistance is measured in Ohms.

Watt – the basic unit of electric, mechanical, or thermal power in the SI and MKS systems, equal to one joule per second or 10 ergs per second (of a horsepower): for electric power it is equal to one volt-ampere.

Electricity is the flow of electrons through a conductor like a wire. The rate at which electricity flows is measured as an electric current. The electric current is measured in amps. What makes the current flow? In your case, the power cord (2.5v) is what creates the pressure to push the current through the power cord. The pressure is the voltage. If the pins on the plug are the same, this plug should work. The only question is the black pin on the top which may be purposely insulated for some reason. This may be worth looking into in case there is a necessity for this based upon the Sony Vaio manufacturer specs. Outside of the black insulated pin, everything else should work just the same. I would suggest looking into the insulated black pin however, before using this cord long term as it may protect against things like the cord overheating when charging, etc.

Replacing timing chain 2004 Mazda 6
ANSWER : Hello – if the mechanic waited until the car was re-assembled after the water pump job to suggest timing chain repair, then "yes", s/he was not doing you any favor. Doing the timing chain repair separately is essentially repeating the labor. There are a number of related parts involved in a timing chain service: the timing chain itself, one or more timing chain guides, a tensioner, an idler puller(sometimes), and various o-rings and seals. Many parts manufacturers package these as a "kit", and the technician simply orders the correct kit for your engine in order to be sure they get all the right bits. I recommend a timing chain service performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.

Okay, I have a ’99 Dodge Ram 2500 w/8.0 V10. The timing chain needs to be replaced. Should I replace the gears also?
ANSWER : Hi there. When changing out the timing chains, it is recommended to replace all the sprockets. The sprockets are worn into the old chains and can cause the new chains to prematurely fail or stretch. You can use a tensioner from an older model as long as the tensioner matches the one that is on your engine. If you need further assistance with your timing chain replacement, then seek out a professional, such as one from Your Mechanic, to help you.

I had my timing belt and water pump replaced 45000 miles ago. Now I am told I need to replace water pump. Is this normal?
ANSWER : Hello there, 45,000 miles is a short lifespan for a water pump on your 2000 Honda Odyssey. There are a few reasons the water pump will need to be replaced, such as a pump bearing failure, water pump seal leak, or rust/contamination damaging the pump. Faults such as rust or particles in the cooling system are formed in the cooling system over time and the parts break down, or regular coolant flushes are not performed. These particles can cause the pump to fail prematurely. It would be a good idea to ask why the water pump needs to be replaced or take note of any symptoms you are experiencing with the car before moving forward with this. If you would like to have an expert give you a second opinion on this, a certified technician from YourMechanic can come to your location to inspect the car and replace the water pump if necessary.