This updated article will describe the steps necessary to replace the spark plugs on a 2003 Kia Sedona minivan. This step-by-step guide should also help those working on comparable Kia Sedona (Kia Carnival) models of relative years that use the same engine combination and similar component locations.
Vehicle Summary:
The KIA Sedona (Kia Carnival) was equipped with a transverse-mounted 3.5L V6 engine. Removing the plastic engine cover (described below) allows access to the front three spark plugs. However, the three rear spark plugs take the majority of time and effort to change because it requires the removal of the upper plenum of the intake manifold to gain access. The ignition design is a 50% coil-over-plug design. I call it a 50% design because it only uses three ignition coils mounted over the front three plugs. The rear spark plugs have a plug wire from one of the three ignition coils on the front three cylinders, sharing the duties. Each of the three coils manages two cylinders.
Using These Instructions:
The information in this document will help you save hundreds of dollars on the common maintenance task of replacing the spark plugs on your Kia Sedona. Professional mechanics and Kia dealerships will charge as much as $950.00 USD in labor costs for this service, but this guide will show you how to accomplish the task for nothing more than the cost of new spark plugs and plug wire leads, along with an afternoon of your time. If these cost savings sound enticing—keep reading.
Disclaimer:
This document has been written for the average do-it-yourself (DIY) person to successfully understand and perform each step. However, the skilled mechanic may also find a few time-saving tips along the way. Before attempting this procedure it is advised that you are familiar with basic automotive engine terminology, and possess the mechanical and physical skills necessary to accomplish this task. You should already own or have access to the proper tools (see list below), understand the safety precautions (noted where needed), and have the time and patience to perform this procedure carefully and as instructed.
We have included a Glossary of Terms on the last page of this document (and bottom of the website). Some words and phrases used in this document may not be familiar to you, so this new glossary feature will help explain these items. Words and phrases highlighted in green will be listed in the glossary, offering definitions, descriptions and additional information.
These instructions have assisted more than 400,000 viewers who found us through Google, Bing, other search engines and from thousands of links from other websites.
The availability of this document is funded by product sales. We can always use new customers which allows us the ability to add more of these free features to our site. If you have any questions, please create a support ticket on our HelpDesk.
Safety Concerns:
There are risks involved anytime work is performed on a motor vehicle. Therefore, it is in everyone’s best interest to carefully follow these instructions and be aware of the safety warnings provided. These symbols may be found throughout this document. Please note each description.
DANGER: Imminent hazard. Failure to avoid will result in severe injury or death.
WARNING: Ignoring this warning could result in injuries or death.
CAUTION: If precaution is not taken, actions may cause minor to moderate injury, or damage to your vehicle
Wearing the proper personal protection equipment (PPE) will help prevent injury to your hands, eyes, and other boy parts. There are many sharp and hazardous areas your hands will be accessing as you work on motor vehicles. Quality cloth or leather gloves that offer a comfortable and secure fit, such as those from Mechanix Wear or a thick nitrile gloves (7-9 mil) offer the best durability.
Protecting your vehicle should also be a concern. You will be leaning over the fenders of the vehicle. Some sort of fender cover should be used to prevent dents or scratches to the fender panels. Large belt buckles can also cause damage as your body weight presses against the fenders.
Required Tools and Other Items:
The most important tool necessary before you get started on this task is patience. This cannot be stressed enough. This vehicle is not difficult to work on, but this task is time-consuming and often requires patient and clear thought before muscle or haste.
- An assortment of metric sockets in both 3/8” and 1/4” drive (specifically 10mm and 12 mm)
- Metric combination wrenches (ratcheting box end wrenches come in handy)
- Spark plug socket & socket extensions (various lengths)
- Screwdriver assortment
- Plier assortment
- Flexible plug starter (example images shown in Step #5)
- Spark Plug Gapping Tool
- Gloves (cloth and/or heavy 8 Mil nitrile) to protect your hands
- Eye protection
- Clean rags / towels
- Wheel blocks or chocks
- Shallow magnetic tray or small box to store fasteners (see best practices below)
- Fender Cover (recommended)
- Anti-Seize paste for the spark plug threads
- Dielectric silicone for plug boots (typically included with new plug wires)
Before Starting This Project:
Here are a few important reminders before you get started.
- Have new spark plugs been purchased?
- Have new plug wires been purchased? Replacing the plug wires optional, but as you will see in the steps below, and in my notes at the end of this document, that it will not hurt to replace the plug leads while you have everything apart. This could prevent time delays and possibly having to do this procedure twice!
NOTE: New plug wire leads usually include a small tube of dielectric silicone to use inside the plug boots. Make sure this is included with your wires, otherwise you will need to purchase a small tube.
- Replacing the plenum gasket can also be optional. If the original gasket is slightly damaged in any way it will require replacement. It is good insurance to purchase a new gasket as the cost is under $20.00 USD. (This is the gasket at the base of the plenum where it seals to the intake manifold).
- Has enough time been allotted to complete this project? If this is someone’s first time performing this task, someone with only limited automotive maintenance experience, or even someone with good mechanical skills, this is an all-day affair, and for some it will be a weekend project. Make sure you have allotted enough time!
- PLEASE READ THROUGH EACH STEP COMPLETELY BEFORE PROCEEDING WITH THAT STEP!
Shopping List:
- Spark Plugs (set of 6). “Avoid gimmick plug designs”
- Anti-Seize Paste
- Spark Plug Wire Set
- Dielectric Grease
- Plenum Gasket
It is time to get to work …
Step 1:
It is best to perform this procedure when the vehicle is on level ground. Use some sort of wheel block on one wheel of the vehicle to prevent rolling. Install a block or wheel chock on the front and rear sides of one wheel. The image at right shows a wheel chock on the backside of one wheel. This is an important safety step
The common wheel chock shown above is from Harbor Freight Tools, part number 96479. Similar wheel chocks or blocks are available from many resellers.
Step 2:
- Remove the NEGATIVE (black cable) from the battery. Loosen the cable hold-down bolt with a 10mm wrench and carefully twist the terminal end up and away from the battery post.
- Remove the POSITIVE (red cable) using the same technique described above.
Note: If the terminal end is too tight to the battery post, the correct way to remove it will be to use a battery terminal puller (shown at left). The need for this tool is uncommon on modern vehicles, but is safer than using other methods.
Step 3:
Remove the air intake tube. This is mounted at the front of the vehicle, just in front of the engine, and connects to the air box where the air filter is located.
Remove the two bolts holding it in place. There is one on either side of where air intake the finger graphics are pointing.- Loosen the hose/line clamp at the air filter box connection, and the assembly will slip off.
Step 4:
Remove the plastic engine cover. There are (6) bolts that hold it in place.
When removing the bolts, BE CAREFUL NOT TO LOSE THE RUBBER SHOCK WASHERS that may be attached to the bolt or stuck in the bolt recess on the cover.
- Remove the six bolts and place them into your box or bolt tray. Be sure to label where they came from.
- Take off the oil filler cap
- Be careful not to drop any dirt, parts, or debris into the open oil filler hole.
- Carefully place a clean rag or towel into the oil filler hole
- Lift the engine cover out of the way
- Remove the rag and replace the oil filler cap to prevent any debris from falling into the engine.
The image below shows each of six the cover bolt locations.
With the engine cover removed, the intake plenum, valve covers, coil packs, plug wires, and the rest of the engine are visible.
Step 5:
Remove and Replace the FRONT three spark plugs (ONE AT A TIME). This will complete the easy part first, and it provides experience prior to working on the more difficult rear spark plugs.
Each coil pack is held in place with two bolts.
WORK ON ONLY ONE CYLINDER AT A TIME! Unbolt ONE coil pack, remove ONLY the plug wire lead connected to that coil pack, and change the spark plug for just that cylinder. Complete the cylinder you are working on before going to the next!
NOTE: Disconnecting the wire harnesses from the coil packs is not required!
1. Remove the plug wire boot from the coil pack. This is the wire that is routed to the left of the engine and headed rearward behind the intake plenum toward the rear three cylinders.
2. Remove the two coil pack hold-down bolts.
NOTE: The spark plug boot for the front cylinders is attached to the bottom of the coil for that cylinder.
3. SLOWLY lift up the coil while twisting the coil pack assembly. Use your free hand to gently bend the spark plug boot up and out of the spark plug hole.
4. Take a long (6” or so) socket extension and a 5/8” spark plug socket to loosen the spark plug.
NOTE: Problems occur if using an incompatible spark plug socket. The wall thickness of some spark plug sockets is quite thick. These may bind on the cylinder head when turning. Do not force it! Use a thinner-walled socket.
5. Use a spark plug starter (images at right show two styles), or piece of rubber hose on the loosened spark plug. The starter will slide snugly over the ceramic portion of the plug. Turn the starter tool to remove the spark plug. We will use this tool to get the threads on new spark plug started during installation.
6. Verify the spark plug gap of your new spark plugs using the proper gapping tool. There should be an emissions sticker under the hood in the engine bay that specifies the correct plug gap. (The recommended gap is usually 1.1 mm.)
REMINDER: Install OE equivalent Platinum Tip Spark Plugs. We want this tune-up to last another 100,000 miles!
7. Slide the new spark plug into the plug starter and apply a small amount of anti-seize to the threads.
a. Anti-Seize is both a lubricant and protectant. Failure to apply anti-seize could cause damage to the cylinder heads. Damage in this area is costly to repair!
b. NOTE: Some spark plug manufacturers state that their plug design offers a special metal plating (Zinc-chromate or similar) on the threads, eliminating the need for anti-seize. They include that this plating “breaks away” from the plug during removal, while preventing damage to the plugs or the threads in the cylinder head at the same time?!? (ngksparkplugs.com). If this sounds odd to you, stick with the application of anti-seize.
8. Carefully thread the new spark plug into the cylinder head. There should be some friction, but it should be steady until it overcomes the holding force of the starter-tool. Remove the starter tool and insert the 5/8” spark plug socket with extension over the plug.
a. The plug should still turn by hand (without the ratchet on the extension) for a few more turns. Do this to verify that the spark plug has not cross-threaded into the cylinder head. This is a rare problem on this engine, especially if you used the plug-starter tool, but is still something to be aware of.
9. Tighten the spark plug, but DO NOT OVER-TIGHTEN.
a. There is a torque specification for spark plugs, but it is rarely used. The easiest way to tighten the plug is “snug” but not with any brute force. If the knuckles on your fingers pulling the ratchet are turning pink, that is all you need! (pink-knuckle tight).
10. Reinstall the coil pack using these steps:
a. Apply a small amount of dielectric silicone to the inside of the plug boot
b. Position the plug boot onto the top of the spark plug and gently twist while pushing down on the coil pack. The boot should slide on smoothly on the spark plug.
c. Align the coil pack mounting holes and install the mounting bolts—snugly but not too tight!
d. Temporarily reinstall the OLD plug wire lead that is running to the rear cylinder (dielectric silicone is not required for this old wire). This prevents losing track of the proper connection.
11. REPEAT THESE STEPS FOR THE OTHER TWO FRONT CYLINDERS.
Step 6 - Preparation to Remove Intake Plenum
Accessing the rear spark plugs requires the removal of the upper intake manifold plenum. Unfortunately, I forgot to take a picture of the wiring harness heat shield/support bracket that attaches to the intake plenum. To make up for this oversight I have drawn in where the bracket would be located. This complex step is broken down into multiple sections, labeled (6a – 6e).
Behind the oil filler cap is a large diameter wire harness inside convoluted tubing (highlighted in the above image). This part of the wiring harness is connected to the metal bracket using a plastic ties that snap through the bracket (note the three slots), and the metal bracket itself has two bolts holding it to the intake plenum. It is NOT necessary to completely remove the bracket from the engine, but you may find that this occurs by default.
6A - Removing the Heat Shield Wiring Support Bracket
- Remove the two bolts and pull the bracket forward. Removing this bracket allows access to the two plenum bolts below it.
- The probability that the three plastic ties will crumble in your hands and fall off is high. They are not worth trying to save. They have become brittle due to age, heat, and poor-quality materials. If these plastic ties break off, remove the pieces and set the bracket aside.
- Thread the two bolts back into the holes or install and label them in your cardboard bolt tray. This prevents loss or misplacement.
6B - Removing the Air Filter Box and Inlet
1. Unbolt the air box (air filter box). There are four easily accessible bolts on upper perimeter.
2. Disconnect the air inlet hose from the air intake.
a. First, remove the vacuum line toward the front. Loosen the hose clamp on the air inlet. (Do not take the screw all the way out of the clamp!)
i. This hose may be difficult to remove. Heat and fuel vapors may have secured it over time. Wiggle it, twist it, etc. It WILL slide off!
3. Disconnect the vacuum line located just below the throttle body, identified by the red arrow in the image below.
a. Use pliers to squeeze the metal hose clamp while gently twisting/pulling the line off of the nipple.
6C - Organizational Support Bracket Removal
On either side of the intake plenum there is a metal bracket that supports various electronic connectors, lines, etc. Unbolt these brackets. Removing these brackets will help provide the room necessary to make removal of the plenum easier.
- Remove the 2 bolts from the bracket to the left, and the three bolts from the bracket to the right (shown in the image below).
- Set the brackets aside (off the vehicle).
- Thread each of the bracket mounting bolts back into their locations so they are not lost, misplaced, or forgotten as to where they go. (Or, place them in your cardboard tray with proper labeling.)
- Now visible are a few connectors that may need disconnection when removing the plenum. There is no need to disconnect them at this time. Only disconnect those that interfere with the necessary movement of the plenum during Step #7.
6D - Driver's Side Connector Removal
The connections on the sides of the plenum are similar to those located on the back of the plenum. These are not only harder to get to, but are often stubborn to remove. Be patient and careful when moving your hand into a position that allows release of these connectors from their sensors.
On the driver’s side rear of the plenum are two large connectors just behind the throttle body. One is black and sort of oval-shaped, and the other is orange and close to square shaped.
- Look at the connectors and locate the lock tab on each connector that allows release from the sensor.
- Carefully pinch (depress) the connector lock tab and then gently pull the plug away from the sensor. It should slide easily if the lock tab was depressed properly.
Review the images below for location and identification of the above connectors.
6E - Rear Plenum Support Bracket Removal
The image above shows the upper-rear portion of the engine and its close relationship to the firewall. Shown in the image are the two upright support brackets—the left bracket just clears the heater hoses going from the engine through the firewall to the heater core, and the right-side bracket has the unplugged electrical connectors lying across it. These brackets on the lower side are bolted to the cylinder head, and the holes at the top of the brackets is where they are bolted to the upper intake plenum.
The Intake Manifold Is Already Unbolted From The Brackets In This Image!
Study the image above to understand the angle of the bolts and their locations, and how they are attached to the intake plenum. There are four bolts that come from the rear, through these brackets, and into the plenum … two on each bracket.
NOTE: The bracket on the left is in two parts, and this image does not identify the upper portion with the engine lift eyelet that sits over the top of the plenum.
- Remove the four bolts that connect these brackets to the plenum.
- Remove the last (fifth) bolt from the upper engine lift bracket (image below).
- Place each of these bolts in your storage tray and label accordingly.
TIP: Ratcheting box end wrenches come in handy to remove these bracket bolts.
Step 7 - Plenum Removal
In this step, we will unbolt the intake manifold plenum from the engine. There are TWO nuts on studs with locking nuts in the middle area, and an additional FIVE bolts on the lower perimeter. PLEASE READ BOTH WARNINGS BELOW BEFORE CONTINUING.
WARNING!
The plenum fasteners apply the clamping and sealing force upon the plenum gasket. Slightly loosen each and then continue to remove the fasteners. BE CAREFUL when lifting up the intake manifold plenum to prevent damage to the existing gasket. The plenum should lift away easily. It may be possible to reuse the existing gasket, if undamaged. However, if any part of the gasket is damaged in any way, it must be replaced. It is a best practice to replace the gasket, but some are trying to save as much expense as possible.
(The cost of a new intake plenum gasket is typically under $20.00 USD)
WARNING!
Please perform a visual inspection of the area around the top of the engine. Especially near the plenum openings, to ensure everything is out of the way. This includes any debris, pieces of broken plastic, ANYTHING!.
When the plenum is lifted, if something falls into the open ports it could damage or destroy the engine. Ensure that nothing can fall into the engine. Have a few clean rags ready to place over or inside of the ports as a precaution.
- Remove each of the fasteners (shown below) that secure the plenum.
- CAREFULLY lift the plenum STRAIGHT UP off the gasket, far enough to slide off the two mounting/alignment studs.
- If you find that something is still connected and preventing you from lifting the plenum high enough, carefully slide the plenum back down over the studs and onto the manifold.
- Disconnect or relocate whatever is limiting plenum movement and then try again.
- Set the plenum off to the side of the studs (toward the front of the vehicle). See second image below.
- It was intentional not to provide instruction of disconnecting any more items on the driver’s side of the engine under the throttle body area. Nothing else should require disconnection or removal to continue the process! Once the plenum is up and off the studs, simply twist it forward (level but turning counter-clockwise) on the passenger side (front of the engine) to allow access to the rear spark plus as shown in the images below.
- Place clean rags over or partially inside each of the ports in the manifold to prevent anything from accidentally falling into the engine.
The image below shows the intake plenum unbolted and twisted forward.
NOTE: Also shown is the DANGEROUSLY OPEN ports before shop rags were placed over them!
Step 8 - Rear Spark Plug Removal
We now have access to and can replace the rear three spark plugs.
- Follow the same procedures as described in Step #5 to remove the spark plugs. There are no coil packs to worry about!
- Twist and lift each plug boot off the spark plug and out of the cylinder head.
- If the boot is stuck, lift of the edge of the boot slightly with your finger and spray a small amount of WD-40 around the underside of the boot.
- Work on only ONE AT A TIME to prevent mixing up the ignition firing order.
- Complete each cylinder by replacing the plug wire lead. Compare the old plug wire lead to the new ones and select one of the corresponding length.
Step 9 - Reassembly
It is time to put everything back together in the opposite sequence from described above. Here are a few reassembly tips to help:
- Replace the plenum to intake gasket if necessary. It is a good choice to replace it! If the original does not seal properly, this entire process will need to be repeated.
- Make sure the harness plugs at the back of the engine are not in the way (positioned on the wrong side of the bracket) when the plenum is returned to its mounted position.
- Set the plenum down slowly, carefully and squarely.
- DO NOT tighten any of the bolts when placing the plenum in place.
- Start ALL of the bolts that connect to the plenum, including the supporting bolts on the rear brackets of the plenum.
- Prevent bolt alignment issues later during reinstallation by following this important step!
- Start each bolt, and THEN tighten the plenum fasteners by hand to bring the plenum against the intake manifold.
- TIGHTEN THE PLENUM FASTENERS IN THE PROPER SEQUENCE. The sequence and tightening over multiple steps is imperative. Increase the tightening force at each step until the plenum is fully tightened. 3-5 steps through the sequence is acceptable. (see image below)
- Tighten down the rear plenum support bracket bolts.
- Reconnect every electrical connector and vacuum line.
- Ensure that all wiring, tubing, and lines are routed and secured properly in their original positions and away from moving parts and excess heat sources.
The remainder of the reinstallation should be straight forward, and upon completion your Kia Sedona will run well for many miles to come
In Closing:
This project was done to help out a friend in need many years ago. Her van was running horribly, and had been for quite some time. She called to ask how a dealership could charge $750.00 for a tune-up (spark plugs and wires). I performed a few online searches to find people in various forums complaining about the costs, and how the intake had to be removed to gain access to the rear plugs. However, no one was posting anything about doing the work themselves.
I told my friend to come over for the weekend and I’d take care of it for her—teaching myself the procedure along the way. I acknowledged that changing the spark plugs may not eradicate all of the problems she was experiencing, but I’d give it a try for her. It was when I was about half-way into this project that I decided to document the nearly all-day excursion so that my efforts might help others.
We chatted as I worked, and I found out that this vehicle was part of a factory recall regarding a problem with the head gaskets or something where the upper part of the engine had to come apart. A (now out of business) Kia dealership had performed the recall repairs, and was the only shop to work on this vehicle while it was under warranty. She included that “some other shop” had performed a HALF tune-up on it some time ago. Yes, I said that correctly—a HALF of a tune-up! The shop only replaced the front three spark plugs and ignored the rear three. (There were two brands of plugs in the engine, where the front and rear were different.)
I had asked my friend what symptoms she was seeing before I started working on it. A “loss of power during freeway acceleration” she stated was the primary and most common issue. Once the intake plenum was removed, and I had access to the rear three rear spark plugs, I could not believe what I found…
The plug boot on the #1 cylinder was shredded by what seems to be the work of someone prying up on the sticking plug boot with a screwdriver or other sharp object … DESTROYING it! This was the most probable cause of the misfire and power loss that her Sedona was experiencing. This plug boot should have been replaced during the prior repair, and the ONLY people to have worked on this vehicle in that area of engine was the dealership mechanic(s) during that warranty repair. Instead of replacing the plug wire, the incompetent or ethically-challenged mechanic put everything back together and sent her on her way. Additionally, it does not seem like the other shop put it on a scope or other diagnostic equipment to identify the misfire.
KIA 3.5L Cylinder Numbering
REAR: 1 – 3 – 5
FRONT: 2 – 4 – 6
Not only was the boot destroyed, but the shielding on the plug wire just within the top of the boot was cut, allowing for an easy escape of spark energy. The perfect excuse for the spark to bypass the spark plug and jump to the closest ground. All the necessary ingredients to create a misfire…
Glossary
Coil-Over-Plug
Also known as direct ignition or a coil-on-plug ignition system. There is no plug wire with this design, just a boot attached to the coil pack that slides over the spark plug.
Image at right shows a Kia Sedona coil and attached spark plug boot for a front cylinder. (This application only uses three coil packs—two cylinders per coil.)
Cross-Threading
This is when the male threads on a bolt or other threaded fastener do not mesh properly with the female threads. The threads grab at an angle instead of lining up proper and cross, causing damage to both the fastener and the receiving threads.
Do-It-Yourself (DIY)
A person who is not a professional, performing a task without special training or assistance.
Fender Cover
Most parts stores offer fender covers for sale. There are different styles and materials available. Some are simply a heavy cloth, while others are made from heavy duty PVC foam vinyl outer layer with a non-slip inner layer. Other styles offer covered magnets to hold the cover to a metal fender surface. Most styles will cover down the fender to about the tire, but long styles are also available. Some are quite elaborate and vehicle-specific. The image at left is a common heavy duty foam/vinyl cover.
The lighter duty covers offer protect from simple scratches, but will not prevent damage from a dropped tool. The foam/vinyl/urethane covers do both, and there is probably a cover available that features some logo or brand advertising that you will find acceptable.
Gapping Tool
The gapping tool is used to verify spark plug gap accuracy based upon vehicle manufacturer’s (or the spark plug manufacturer’s) specification.
NOTE: There are “checking” tools and “gap pliers” (adjustment pliers). The checking tool should be adequate, and these are often sitting out next to the cash register as an impulse purchase at the local parts store. Changes to the gap are rarely required for OEM vehicle applications, but double-checking the gap is important before installation.
DO NOT USE THE CENTER ELECTRODE OF THE SPARK PLUG TO PRY AGAINST! Use needle-nose pliers to gently move the ground strap to open the plug gap.
Ignition Coil
A special type of simple transformer that generates the high voltages required to create the spark that ignites the air/fuel mixture during the combustion process.
Ignition Firing Order
Every combustion engine has a Firing Order that identifies the sequence in which each cylinder receives its spark. If the firing order is not correct, for example installing a plug wire lead on the wrong spark plug, the engine will run rough—if it runs at all.
Most engines do not have a sequential firing order, but in the case of the 3.5L Kia V6 engine, it is sequential with a firing order of:
1 – 2 – 3 – 4 – 5 – 6
The actual cylinder numbering for the KIA 3.5L engine:
REAR: 1 – 3 – 5
FRONT: 2 – 4 – 6
Pink-Knuckle Tight
A condition where the knuckles on the hand applying force to the tool it is holding turns pink (discolors slightly) from the mildly cutoff circulation in the fingertips.
Transverse-Mounted
A transverse-mounted engine is one where the vehicle design incorporates an engine placement which is perpendicular to the length of the vehicle. The engine’s crankshaft is 90° to that of the vehicle.
Most front-wheel drive vehicles use this configuration, compared to the longitudinal engine placement of most rear-wheel drive vehicles. In longitudinal placement, the crankshaft is parallel to the length of the vehicle.
