We were recently investigating the engine area
of our 2001 Jeep Grand Cherokee,
and noticed the spark plugs (4L 6cyl)
are connected with a power rail and
what appears to be small wires to each plug.

I looked around, but could not find an article
showing how this has replaced the plug & ignition wire ?

Any photos or explanations of the power rail
vs traditional ignition setups.

 

OPERATION

The 4.0L 6-cylinder engine uses a one-piece coil

rail containing three independent coils. Although cylinder

firing order is the same as 4.0L engines of previous

years, spark plug firing is not. The 3 coils dualfire

the spark plugs on cylinders 1-6, 2-5 and/or 3-4.

When one cylinder is being fired (on compression

stroke), the spark to the opposite cylinder is being

wasted (on exhaust stroke). The one-piece coil bolts

directly to the cylinder head. Rubber boots seal the

secondary terminal ends of the coils to the top of all

6 spark plugs. One electrical connector (located at

the rear end of the coil rail) is used for all three coils.

Because of coil design, spark plug cables (secondary

cables) are not used on either engine. A distributor

is not used with either the 4.0L or 4.7L

engines.

The ignition system is controlled by the powertrain

control module (PCM) on all engines.

The ignition system consists of:

Spark Plugs

Ignition Coil(s)

Powertrain Control Module (PCM)

Crankshaft Position Sensor

Camshaft Position Sensor

The MAP, TPS, IAC and ECT also have an effect

on the control of the ignition system.







"Phil Schuman" <pschuman_NO_SPAM_ME@interserv.com> wrote in message
news:j4d7g.67317$_S7.65364@newssvr14.news.prodigy. com...
> We were recently investigating the engine area
> of our 2001 Jeep Grand Cherokee,
> and noticed the spark plugs (4L 6cyl)
> are connected with a power rail and
> what appears to be small wires to each plug.
>
> I looked around, but could not find an article
> showing how this has replaced the plug & ignition wire ?
>
> Any photos or explanations of the power rail
> vs traditional ignition setups.
>
>

 

OPERATION

The 4.0L 6-cylinder engine uses a one-piece coil

rail containing three independent coils. Although cylinder

firing order is the same as 4.0L engines of previous

years, spark plug firing is not. The 3 coils dualfire

the spark plugs on cylinders 1-6, 2-5 and/or 3-4.

When one cylinder is being fired (on compression

stroke), the spark to the opposite cylinder is being

wasted (on exhaust stroke). The one-piece coil bolts

directly to the cylinder head. Rubber boots seal the

secondary terminal ends of the coils to the top of all

6 spark plugs. One electrical connector (located at

the rear end of the coil rail) is used for all three coils.

Because of coil design, spark plug cables (secondary

cables) are not used on either engine. A distributor

is not used with either the 4.0L or 4.7L

engines.

The ignition system is controlled by the powertrain

control module (PCM) on all engines.

The ignition system consists of:

Spark Plugs

Ignition Coil(s)

Powertrain Control Module (PCM)

Crankshaft Position Sensor

Camshaft Position Sensor

The MAP, TPS, IAC and ECT also have an effect

on the control of the ignition system.







"Phil Schuman" <pschuman_NO_SPAM_ME@interserv.com> wrote in message
news:j4d7g.67317$_S7.65364@newssvr14.news.prodigy. com...
> We were recently investigating the engine area
> of our 2001 Jeep Grand Cherokee,
> and noticed the spark plugs (4L 6cyl)
> are connected with a power rail and
> what appears to be small wires to each plug.
>
> I looked around, but could not find an article
> showing how this has replaced the plug & ignition wire ?
>
> Any photos or explanations of the power rail
> vs traditional ignition setups.
>
>

 

OPERATION

The 4.0L 6-cylinder engine uses a one-piece coil

rail containing three independent coils. Although cylinder

firing order is the same as 4.0L engines of previous

years, spark plug firing is not. The 3 coils dualfire

the spark plugs on cylinders 1-6, 2-5 and/or 3-4.

When one cylinder is being fired (on compression

stroke), the spark to the opposite cylinder is being

wasted (on exhaust stroke). The one-piece coil bolts

directly to the cylinder head. Rubber boots seal the

secondary terminal ends of the coils to the top of all

6 spark plugs. One electrical connector (located at

the rear end of the coil rail) is used for all three coils.

Because of coil design, spark plug cables (secondary

cables) are not used on either engine. A distributor

is not used with either the 4.0L or 4.7L

engines.

The ignition system is controlled by the powertrain

control module (PCM) on all engines.

The ignition system consists of:

Spark Plugs

Ignition Coil(s)

Powertrain Control Module (PCM)

Crankshaft Position Sensor

Camshaft Position Sensor

The MAP, TPS, IAC and ECT also have an effect

on the control of the ignition system.







"Phil Schuman" <pschuman_NO_SPAM_ME@interserv.com> wrote in message
news:j4d7g.67317$_S7.65364@newssvr14.news.prodigy. com...
> We were recently investigating the engine area
> of our 2001 Jeep Grand Cherokee,
> and noticed the spark plugs (4L 6cyl)
> are connected with a power rail and
> what appears to be small wires to each plug.
>
> I looked around, but could not find an article
> showing how this has replaced the plug & ignition wire ?
>
> Any photos or explanations of the power rail
> vs traditional ignition setups.
>
>