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2008 misfire not consistent


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My 2008 SRX4 has thrown error codes twice for misfire on cylinders 1 and 3. It doesn't run badly most of the time. It has had two start ups that were very rough, but eventually settled in to idle "ok'. I won't say great, but it wasn't obvious to the untrained ear that the car was missing or rough. The mileage is at 59,000. I have had the timing chain replaced already with no obvious residual issues.

My concern is that I will spend multiple hours and a few busted knuckles/fingernails trying to replace coils and have that not be the problem. Wouldn't the car run/start rough all of the time if the coils were bad. Shouldn't I be able to tell there is a bad conduction issue in there?

I cannot have the car out of service for any length of time....any ideas.I am sorry. I know this horse and beaten to death already in reference to older models...

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At this point, I would inspect things to see what is going on

The slight miss you are talking about could be related to moisture that burns off or a bad plug or carbon tracking on the plug

This could be moisture in the fuel also, or a bad fuel filter causing a drop in fuel pressure also have you checked fuel pressure on first startup?

Are these the original plugs? If they are the platinum plugs it could be that you lost the platinum pads we have seen that and I am not sure if that has been resolved.

How did you determine that it was cylinders 1 and 3 misfiring? Did you get codes P301 and P303?

This is out of the service manual, ignore the numbers that are referenced they refer to exhibits

    Spark Plug Usage
  • Ensure that the correct spark plug is installed. An incorrect spark plug causes driveability conditions. Refer to Ignition System Specifications for the correct spark plug.
  • Ensure that the spark plug has the correct heat range. An incorrect heat range causes the following conditions:
    • Spark plug fouling--Colder plug
    • Pre-ignition causing spark plug and/or engine damage--Hotter plug

Inspect the terminal post (1) for damage.

  • Inspect for a bent or broken terminal post (1).
  • Test for a loose terminal post (1) by twisting and pulling the post. The terminal post (1) should NOT move.

Inspect the insulator (2) for flashover or carbon tracking, soot. This is caused by the electrical charge traveling across the insulator (2) between the terminal post (1) and ground. Inspect for the following conditions:

  • Inspect the spark plug boot for damage.
  • Inspect the spark plug recess area of the cylinder head for moisture, such as oil, coolant, or water. A spark plug boot that is saturated causes arcing to ground

Inspect the insulator (2) for cracks. All or part of the electrical charge may arc through the crack instead of the electrodes

Inspect for evidence of improper arcing.

  • Measure the gap between the center electrode (4) and the side electrode (3) terminals. Refer to Ignition System Specifications . An excessively wide electrode gap can prevent correct spark plug operation.
  • Inspect for the correct spark plug torque. Refer to Ignition System Specifications . Insufficient torque can prevent correct spark plug operation. An over torqued spark plug, causes the insulator (2) to crack.
  • Inspect for signs of tracking that occurred near the insulator tip instead of the center electrode (4).
  • Inspect for a broken or worn side electrode (3).
  • Inspect for a broken, worn, or loose center electrode (4) by shaking the spark plug.
    • A rattling sound indicates internal damage.
    • A loose center electrode (4) reduces the spark intensity.

    [*]Inspect for bridged electrodes (3, 4). Deposits on the electrodes (3, 4) reduce or eliminates the gap.[*]Inspect for worn or missing platinum pads on the electrodes (3, 4), if equipped.[*]Inspect for excessive fouling.

Inspect the spark plug recess area of the cylinder head for debris. Dirty or damaged threads can cause the spark plug not to seat correctly during installation

Spark Plug Visual Inspection Normal operation--Brown to grayish-tan with small amounts of white powdery deposits are normal combustion by-products from fuels with additives. <li>Carbon fouled--Dry, fluffy black carbon, or soot caused by the following conditions:

  • Rich fuel mixtures
    • Leaking fuel injectors
    • Excessive fuel pressure
    • Restricted air filter element
    • Incorrect combustion

    [*]Reduced ignition system voltage output

    • Weak coils
    • Worn ignition wires
    • Incorrect spark plug gap

    [*]Excessive idling or slow speeds under light loads can keep spark plug temperatures so low that normal combustion deposits may not burn off.

Deposit fouling--Oil, coolant, or additives that include substances such as silicone, very white coating, reduces the spark intensity. Most powdery deposits will not effect spark intensity unless they form into a glazing over the electrode

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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xyxuhy,

I apologize for the problems you are experiencing with your vehicle. Please keep us posted when everything has been taken care of.

Thank you,

Caron, Cadillac Customer Service

My 2008 SRX4 has thrown error codes twice for misfire on cylinders 1 and 3. It doesn't run badly most of the time. It has had two start ups that were very rough, but eventually settled in to idle "ok'. I won't say great, but it wasn't obvious to the untrained ear that the car was missing or rough. The mileage is at 59,000. I have had the timing chain replaced already with no obvious residual issues.

My concern is that I will spend multiple hours and a few busted knuckles/fingernails trying to replace coils and have that not be the problem. Wouldn't the car run/start rough all of the time if the coils were bad. Shouldn't I be able to tell there is a bad conduction issue in there?

I cannot have the car out of service for any length of time....any ideas.I am sorry. I know this horse and beaten to death already in reference to older models...

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