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General information

Both the 4.0L 6–cylinder and the 4.7L V-8 engine use resistor type spark plugs. 4.7L V-8 engines are equipped v “fired in suppressor seal” type spark plugs making use of a copper core ground electrode. Because of the usage of an aluminum cylinder head top top the 4.7L engine, spark plug torque is an extremely critical. To prevent feasible pre-ignition and/or mechanical engine damage, the exactly type/heat range/number spark plug have to be used.

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The 4.7L V–8 engine provides 8 dedicated, and individually fired coil for each spark plug. Each coil is an installed directly to the height of every spark plug. Battery voltage is provided to the 8 ignition coils from the ASD relay. The Powertrain regulate Module advance. This is done to meet changing engine operating conditions. The ignition coil is no oil filled. The windings are installed in one epoxy compound. This provides heat and vibration resistance that enables the ignition coil come be an installed on the engine. Because of coil design, spark plug cables (secondary cables) are not used.

Some fuel refiners in several locations of the joined States have actually introduced a manganese additive (MMT) for unleaded fuel. Throughout combustion, fuel v MMT reasons the entire tip that the spark plug to be coated with a rust fancy deposit. This rust color can it is in misdiagnosed together being brought about by coolant in the burning chamber. Spark plug performance may be affected by MMT deposits.


Cold fouling is sometimes referred to together carbon fouling. The store that reason cold fouling room basically carbon. A dry, black color deposit top top one or 2 plugs in a collection may be resulted in by difficult valves or defective spark plug cables. Cold (carbon) fouling of the entire collection of spark plugs may be caused by a clogged wait cleaner aspect or repeated short operating times (short trips).


A spark plug coated with excessive wet fuel or oil is wet fouled. In larger engines, worn piston rings, leaking valve overview seals or excessive cylinder stay can reason wet fouling. In brand-new or newly overhauled engines, wet fouling might occur prior to break-in (normal oil control) is achieved. This condition can typically be resolved by cleaning and also reinstalling the fouled plugs.


If one or an ext spark plugs room oil or oil ash encrusted, evaluate engine problem for the cause of oil entry right into that details combustion chamber.


a normal problem caused by chemistry additives in details fuels. This additives space designed to adjust the chemistry nature of deposits and also decrease spark plug misfire tendencies. Notification that accumulation on the soil electrode and shell area might be heavy, yet the store are quickly removed. Spark plugs v scavenger deposits have the right to be thought about normal in condition and can it is in cleaned using conventional procedures.


A chipped electrode insulator usually outcomes from bending the facility electrode while adjusting the spark plug electrode gap. Under certain conditions, major detonation can also separate the insulator native the facility electrode. Spark plugs through this problem must be replaced.


Pre-ignition damage is usually resulted in by excessive combustion chamber temperature. The center electrode dissolves very first and the soil electrode dissolves somewhat latter. Insulators appear relatively deposit free. Identify if the spark plug has actually the correct heat variety rating because that the engine. Recognize if ignition timing is over progressed or if various other operating problems are causing engine overheating. (The heat range rating refers to the operation temperature of a particular kind spark plug. Spark plugs are designed to run within particular temperature ranges. This counts upon the thickness and length the the facility electrodes porcelain insulator.)


Overheating is indicated by a white or gray center electrode insulator that likewise appears blistered. The boost in electrode space will be considerably in excess of 0.001 customs per 2000 miles of operation. This argues that a plug through a cooler heat range rating must be used. Over advanced ignition timing, detonation and cooling device malfunctions can likewise cause spark plug overheating.

CLEANING and GAPPING (Except HO engines)

The plugs may be cleaned utilizing commercially obtainable spark plug cleaning equipment. ~ cleaning, paper center electrode flat with a small point file or jewelers document before adjusting gap. The void specification is 0.035 for the 4.0L engine, and also 0.040 for the 4.7L engine.

CAUTION: never ever use a motorized wire wheel brush come clean spark plugs. Metallic shop will remain on spark plug insulator and also will cause plug misfire.

CLEANING and also GAPPING (HO engines)

Never clean spark plugs on the 4.7L H.O. Engine. Damages to the platinum rivet will result. Also, execute not use a wire-type gapping device for the very same reason. Use a tapered-type gauge. The space specification is 0.040 for the 4.7L HO engine.

PLUG remove & environment – 4.0L

A one-piece coil rail assembly containing three individual coils is provided on the 4.0L engine. The bottom of the coil is equipped v 6 individual rubber boots come seal the 6 spark plugs come the coil. Within each rubber boot is a spring. The spring is supplied for an electric contact between the coil and the peak of the spark plug. Originally, the rubber boots and also springs to be not marketed separately, the whole coil rail through boots had actually to be purchased as one assembly. The boots/springs space now accessible separately from Mopar and from auto components stores.


Tips: 6″ socket extension; use anti-sieze in the rubber socket for simple release turn off the plugs

1. Disconnect negative battery cable at battery.

2. The coil rail assembly should be eliminated to gain access to any/all spark plugs. The coil is bolted directly to the cylinder head. Eliminate the 4 coil mounting bolts.


3. Closely pry up coil assembly indigenous spark plugs. Execute this by prying alternately in ~ each end of coil till rubber boots have disengaged from every spark plugs. If boots will certainly not release from spark plugs, use a commercially easily accessible spark plug boot removal tool. Twist and loosen a couple of boots indigenous a few spark plugs to assist remove coil.

4. After ~ coil has actually cleared spark plugs, position coil for accessibility to primary electrical connector. Disconnect connector native coil by pushing slide tab outwards to ideal side the vehicle. After on slide tab has actually been positioned outwards, push in on secondary release lock on side of connector and pull connector indigenous coil.

5. Eliminate coil native vehicle.

6. Prior to removing spark plugs, spray compressed air roughly spark plug hole and also area roughly spark plug. This will aid prevent foreign material native entering burning chamber.

4. Remove spark plug indigenous cylinder head making use of a 5/8″ spark plug socket v a rubber insert. The rubber insert form socket is forced to remove the spark plug indigenous the fine after it is unthreaded.

5. Keep in mind spark plug condition. You may want to note the cylinder # on each provided plug as they room removed.

6. If boots room worn or damaged they have to be replaced. To remove the rubber boots traction firmly and they will come best off. To eliminate the spring, pull and stretch that a tiny bit, and also then twisted counterclockwise to remove.


Special treatment should be taken as soon as installing spark plugs right into cylinder head spark plug wells. Be certain plugs execute not drop right into plug wells together ground straps may be bent bring about a change in plug gap, or electrodes deserve to be damaged.

Always tighten spark plugs to mentioned torque. End tightening can cause distortion leading to a adjust in spark plug space or a cracked porcelain insulator.

1. Verify the each plug is correctly gapped come 0.035. Apply a little amount of anti-sieze come the plug threads. Start spark plug right into cylinder head by hand to avoid cross threading. It’s ideal to execute this through using just the socket expansion bar and socket. Very closely turn slowly while keeping the expansion bar together vertical as possible. Girlfriend should have the ability to screw the plug all the method in by hand until it “seats” snugly.

2. Tighten spark plugs come 26-30 ft. Lbs. (35-41 N·m) torque. If you carry out not have a speak wrench install plugs snug and then turn 1/4 turn.

3. Affix engine harness connector come coil through snapping right into position. Move slide tab towards engine for a positive lock.

4. Position ignition coil rubber boots to every spark plugs. Push down top top coil assembly until bolt bases have contacted cylinder head.

5. Download 4 coil mounting bolts. Loose tighten 4 bolts just enough to allow bolt bases to call cylinder head. Execute a last tightening of every bolt in measures down come 250 in. Lbs. (29 N·m) torque. Perform not use full speak to any type of bolt first.

6. Connect an unfavorable battery cable to battery.

7. To replace worn boots/springs, install the new spring by just pushing the feather onto its write-up (no twisting needed). Push the brand-new boots on end the new spring.

PLUG remove & INSTALLATION4.7L V-8 / 4.7L V-8 HO

Note: 4.7L V-8 = engine VIN password “N”; 4.7L V-8 HO engine = VIN code “J”

CAUTION: The traditional 4.7L engine offers copper core ground electrode spark plugs, they have to be replaced with the exact same type/number spark plug together the original. If one more spark plug is substituted, pre-ignition will certainly result.

CAUTION: never ever substitute the original platinum tipped HO spark plug through a different part number. Serious engine damages may result.. HO plugs cannot be cleaned, damage to the platinum rivet will result. Also, execute not use a wire-type gapping tool for the same reason. Use a tapered-type gauge. Come prevent feasible pre-ignition and/or mechanical engine damage, the correct type/heat range/number spark plug should be used.*NOTE ~ above 4.7 HO plugs: Champion RC7PYCB4 (p/n 3340) is the very same as Mopar SPRC7PYCB4 and can be purchased because that a portion of the expense that Mopar charges.

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Spark plug removal

Each separation, personal, instance ignition coil should be gotten rid of to gain access to every spark plug. The coil fits right into machined feet in the cylinder head. A mounting stud/nut secures each coil come the top of the intake manifold. The bottom the the coil is equipped v a rubber boot to seal the spark plug come the coil. One o-ring is offered to seal the coil in ~ the opening right into the cylinder head. Within each rubber boots is a spring. The spring is provided for a mechanical contact in between the coil and the peak of the spark plug. Originally, the rubber boots and springs to be not marketed separately, the whole coil rail v boots had actually to it is in purchased as one assembly. The boots/springs are now available separately from Mopar and from auto components stores.