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On my Eldo I still get a stutter every time I start it whether hot or cold, a quick jab of the throttle clears it up. It has to be moving, if you rev it in park it will not clear up. It will throw a random misfire code P0300 If you just try to drive normal. A friend of mine put it on a tech 2 scanner and told me when it is misfiring cylinders 1357 are not firing. He is not familiar with coil packs and doesn't know if you can check them, if it is in the wiring to the coil pack or if each coil is a seperate coil or that the whole coil pack can be bad. Anyone know how to check if a coil pack is bad? Is the coil pack one large coil being replaced as a unit? Can you replace one coil? If they are individually replaceable then it would make sense the wiring to the coil pack is bad. Otherwise maybe the whole coil pack is bad.

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This is going to become more of an issue as the 2000+ engines accumulate miles. The COP ignition system design requires that the entire bank of coils be replaced due to the design of the ignition modules (to the benefit of GM's assembly costs).

There is no GM part number (that I can find) for the indivudual coils.

Not a DIY consumer-friendly design.


Drive your car.

Use your cell phone.


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Since you didnt cite any, I assume its not throwing any codes besides the misfire code? Look through this info, it gives some interesting info that could be useful, note how 1,3,5,and 7 are not controlled by the same controller..

DTC P1359 Ignition Coil Group 1 Control Circuit

Refer to Engine Control Schematics Ignition Control Module - Rear Bank and Ignition Control Module - Front Bank .

Circuit Description

The electronic ignition system uses an individual ignition coil for each cylinder. There are two separate ignition module assemblies located in the camshaft cover of each cylinder bank. Each ignition module assembly contains an ignition control module and four ignition coils. Each ignition coil connects directly to a spark plug using a boot. This arrangement eliminates the need for secondary ignition wires. The ignition module assemblies receive power from a fused ignition feed. Both ignition module assemblies connect to chassis ground. A Reference Low and four ignition control (IC) circuits connect each ignition module assembly to the PCM. The PCM uses the individual IC circuits to control coil sequencing and spark timing for each ignition coil. The IC circuits transmit timing pulses from the PCM to the ignition control module to trigger the ignition coil and fire the spark plug. The PCM monitors each IC circuit for improper voltage levels. The PCM also monitors the IC circuits in two groups. The groups consist of every other cylinder in the cylinder firing order (i.e., 1/7/4/6; 2/3/5/8). The PCM monitors the IC circuit group to detect improper voltage levels that occur randomly. If the PCM detects an improper voltage condition in the IC circuit group for #1, #4, #6, and/or #7 cylinders, DTC P1359 will set.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

During PCM power-up, the PCM detects an open circuit condition in the IC circuit group for #1, #4, #6 and/or #7 cylinders. OR

The PCM detects a short to voltage condition in the IC circuit group for #1, #4, #6 and/or #7 cylinders.

The condition is present for less than 1 second.

Action Taken When the DTC Sets

The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails.

The PCM stores the conditions present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC

The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.

The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

The DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Aids

The Misfire Current Cyl # / Misfire History Cyl # displays on the scan tool provides information that may be useful in diagnosing DTC P1359. The Misfire Current Cyl # counter may normally display a small amount of activity (0-10 counts). However, the display should not increment steadily. If the Misfire Current Cyl # increments steadily for a single cylinder within the IC circuit group, the condition is isolated to the IC circuit for the specific cylinder. However, if the Misfire Current Cyl # increments randomly within the IC circuit group, the condition may be due to poor connections at the PCM or a faulty PCM. Also, if the Misfire Current Cyl # increments steadily for a cylinder bank, DTC P1360 may set.

The condition may be the result of the following conditions:

Loss of power or ground at the module assembly for the cylinder bank.

Poor or disconnected module assembly connector for the cylinder bank.

Faulty ignition control module.

If the condition is intermittent, refer to Intermittent Conditions in Symptoms.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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  • 1 year later...

I have a 99 STS giving the P0300 code. I just had the engine replaced was told new wires and plugs were installed. I have had the coil packs checked and replaced three of them, I had the module checked it tested okay. The car does not like to start, when it does start it bounces and idles rough. When I am driving it seems to run well. If I shut the car down and start it right back up it starts so so. If i let it sit again it will crank and crank then start. Please help I had the car 7 days and the head gasket blew, I was told I bought it with a repaired cracked block.

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"note how 1,3,5,and 7 are not controlled by the same controller.."(?)

'1,3,5,7' would be a rear bank coil issue.

Personally, I carry a spare coil bank in the trunk.

There are 2 'different' coil banks available. Forward bank is painted silver, rear bank is black. They are interchangeable.

I attached a pic of one of my spare coils. Right hand side there is also a mounted IC module. (see dog leg).


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