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General information

Both the 4.0L 6–cylinder and also the 4.7L V-8 engine usage resistor kind spark plugs. 4.7L V-8 engines room equipped with “fired in suppressor seal” type spark plugs making use of a copper main point ground electrode. Because of the use of one aluminum cylinder head top top the 4.7L engine, spark plug torque is very critical. Come prevent feasible pre-ignition and/or mechanically engine damage, the correct type/heat range/number spark plug must be used.

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The 4.7L V–8 engine supplies 8 dedicated, and also individually fired coil for each spark plug. Each coil is an installed directly come the optimal of every spark plug. Battery voltage is gave to the 8 ignition coils indigenous the ASD relay. The Powertrain regulate Module advance. This is done to meet an altering engine operation conditions. The ignition coil is no oil filled. The windings are installed in one epoxy compound. This gives heat and also vibration resistance that enables the ignition coil come be mounted on the engine. Since of coil design, spark plug cables (secondary cables) space not used.

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


Cold fouling is periodically referred to as carbon fouling. The store that reason cold fouling are basically carbon. A dry, black deposit top top one or 2 plugs in a collection may be caused by difficult valves or defective spark plug cables. Cold (carbon) fouling the the entire collection of spark plugs might be caused by a clogged air cleaner element or repeated brief operating time (short trips).


A spark plug coated with too much wet fuel or oil is wet fouled. In larger engines, worn piston rings, leaking valve guide seals or extreme cylinder stay can cause wet fouling. In brand-new or recently overhauled engines, wet fouling might occur before break-in (normal oil control) is achieved. This problem can usually be addressed by cleaning and also reinstalling the fouled plugs.


If one or more spark plugs are oil or oil ash encrusted, evaluate engine condition for the cause of oil entry into that certain combustion chamber.


a normal problem caused by chemical additives in certain fuels. These additives room designed to readjust the chemical nature the deposits and also decrease spark plug misfire tendencies. Notice that build-up on the ground electrode and shell area might be heavy, yet the shop are quickly removed. Spark plugs through scavenger deposits can be considered normal in condition and also can be cleaned using standard procedures.


A chipped electrode insulator usually outcomes from bending the center electrode while adjusting the spark plug electrode gap. Under specific conditions, severe detonation can likewise separate the insulator native the center electrode. Spark plugs v this condition must it is in replaced.


Pre-ignition damage is usually brought about by excessive burning chamber temperature. The center electrode dissolves an initial and the floor electrode dissolves rather latter. Insulators appear relatively deposit free. Determine if the spark plug has actually the exactly heat variety rating for the engine. Determine if ignition time is over progressed or if other operating conditions are resulting in engine overheating. (The heat selection rating refers to the operation temperature the a particular kind spark plug. Spark plugs are designed to operate within certain temperature ranges. This depends upon the thickness and also length the the facility electrodes porcelain insulator.)


Overheating is suggested by a white or gray center electrode insulator that additionally appears blistered. The rise in electrode gap will be significantly in overabundance of 0.001 inch per 2000 miles of operation. This suggests that a plug with a cooler heat range rating need to be used. Over advanced ignition timing, detonation and also cooling system malfunctions can also cause spark plug overheating.

CLEANING and also GAPPING (Except HO engines)

The plugs might be cleaned using commercially available spark plug cleaning equipment. After ~ cleaning, paper center electrode flat with a tiny point record or jewelers document before adjusting gap. The void specification is 0.035 for the 4.0L engine, and 0.040 because that the 4.7L engine.

CAUTION: never ever use a motorized cable wheel brush to clean spark plugs. Metallic store will stay on spark plug insulator and also will reason plug misfire.

CLEANING and also GAPPING (HO engines)

Never clean spark plugs ~ above the 4.7L H.O. Engine. Damages to the platinum rivet will certainly result. Also, carry out not use a wire-type gapping device for the exact same reason. Usage a tapered-type gauge. The void specification is 0.040 because that the 4.7L HO engine.

PLUG remove & environment – 4.0L

A one-piece coil rail assembly containing three individual coils is offered on the 4.0L engine. The bottom that the coil is equipped v 6 separation, personal, instance rubber boots come seal the 6 spark plugs come the coil. Inside each rubber boots is a spring. The spring is used for an electric contact between the coil and the height of the spark plug. Originally, the rubber boots and also springs to be not sold separately, the entire coil rail v boots had actually to be purchased together one assembly. The boots/springs room now easily accessible separately indigenous Mopar and from auto parts stores.


Tips: 6″ socket extension; usage anti-sieze in the rubber socket for easy release off the plugs

1. Disconnect an unfavorable battery cable at battery.

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


3. Very closely pry increase coil assembly indigenous spark plugs. Perform this through prying alternately in ~ each end of coil until rubber boots have disengaged from every spark plugs. If boots will certainly not relax from spark plugs, usage a commercially accessible spark plug boot removal tool. Twist and also loosen a couple of boots indigenous a few spark plugs to aid remove coil.

4. After ~ coil has cleared spark plugs, place coil for access to primary electric connector. Disconnect connector from coil by pushing slide tab outwards to ideal side that vehicle. After slide tab has actually been positioned outwards, press in on secondary release lock on next of connector and pull connector from coil.

5. Eliminate coil indigenous vehicle.

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

4. Eliminate spark plug native cylinder head utilizing a 5/8″ spark plug socket with a rubber insert. The rubber insert type socket is required to eliminate the spark plug indigenous the well after it is unthreaded.

5. Keep in mind spark plug condition. You may want to mark the cylinder # ~ above each offered plug together they are removed.

6. If boots space worn or damaged they need to be replaced. To remove the rubber boots traction firmly and they will certainly come appropriate off. To remove the spring, pull and also stretch it a little bit, and then twisted counterclockwise come remove.


Special treatment should be taken once installing spark plugs into cylinder head spark plug wells. Be sure plugs perform not drop into plug wells as ground straps might be bent resulting in a change in plug gap, or electrodes can be damaged.

Always tighten spark plugs to mentioned torque. End tightening can cause distortion resulting in a change in spark plug gap or a cracked porcelain insulator.

1. Verify the each plug is properly gapped to 0.035. Apply a small amount of anti-sieze come the plug threads. Start spark plug into cylinder head by hand to stop cross threading. It’s best to carry out this by using simply the socket expansion bar and socket. Very closely turn progressively while maintaining the extension bar as vertical as possible. Friend should have the ability to screw the plug all the way in by hand till it “seats” snugly.

2. Tighten spark plugs come 26-30 ft. Lbs. (35-41 N·m) torque. If you do not have actually a talk wrench download plugs snug and then revolve 1/4 turn.

3. Attach engine exploit connector come coil by snapping into position. Relocate slide tab towards engine for a positive lock.

4. Position ignition coil rubber boots to every spark plugs. Press down on coil assembly till bolt bases have contacted cylinder head.

5. Download 4 coil mounting bolts. Loosely tighten 4 bolts just enough to permit bolt bases to contact cylinder head. Carry out 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 come battery.

7. To replace worn boots/springs, install the new spring by merely pushing the feather onto its short article (no twisting needed). Press the new boots on end the brand-new spring.

PLUG removal & 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 password “J”

CAUTION: The traditional 4.7L engine provides copper core ground electrode spark plugs, they have to be replaced with the same type/number spark plug as the original. If an additional spark plug is substituted, pre-ignition will result.

CAUTION: never substitute the initial platinum tipped HO spark plug through a different part number. Major engine damage may result.. HO plugs can not be cleaned, damage to the platinum rivet will certainly result. Also, carry out not use a wire-type gapping tool for the very same reason. Use a tapered-type gauge. To prevent feasible pre-ignition and/or mechanical engine damage, the exactly type/heat range/number spark plug have to be used.*NOTE top top 4.7 HO plugs: Champion RC7PYCB4 (p/n 3340) is the exact same as Mopar SPRC7PYCB4 and also can be purchased because that a fraction of the cost that Mopar charges.

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Spark plug removal

Each separation, personal, instance ignition coil must be removed to gain access to each spark plug. The coil fits right into machined holes in the cylinder head. A mounting stud/nut secures every coil come the optimal of the entry manifold. The bottom the the coil is equipped with a rubber boots to seal the spark plug to the coil. One o-ring is used to seal the coil at the opening right into the cylinder head. Inside each rubber boot is a spring. The feather is provided for a mechanical contact between the coil and the optimal of the spark plug. Originally, the rubber boots and springs were not offered separately, the entire coil rail v boots had to be purchased as one assembly. The boots/springs are now available separately from Mopar and also from auto parts stores.