What would cause a 2003 chevy impala's coil pack to break down?

You can try unplugging one of the spark plug wires from the coil pack and then touching it to a metal surface, you should see a spark. If you do then that wire and plug are good. Do this to each wire to check for spark. If they all have spark, ensure that they are plugged in the correct order. If they are you may have a faulty coil pack. You can pick one up on ebay super cheap.

Cylinder # 3 has a misfire...#1) Defective coil on plug or the spark plug itself...#2) Contaminated fuel injector...See drawings below...The coil pack is the smaller of the two and sits to the rear of engine it is the most probable cause...Although the spark plug or the ignition wire (connection between plug and coil pack) could be at fault...so, before you invest in a new coil pack...Remove from both ends the wire from #3 and switch it with #2...if the fault code changes to p0302 that wire is bad...next Install a new set of plugs....Fault still present? replace the coil pack.....Unless recently changed new plugs and wires are a plus even if fault remains...saailer





Cost= about $90

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With the vehicle running remove the plug for the fuel injector for cylinder #3. RPM should drop. If you have access to nous lights plug one into the injector plug and make sure it flashes. If no flash either the wiring is open or grounded or the computer is not commanding it on and off. You should also look at the cylinder compression. Make sure plugs aren't cracked, are correctly gapped, and no carbon tracking.

For spark plug problem,click the help links provided below :---Car has no spark?http://schematicsdiagram.blogspot.com/2011/06/car-has-no-spark.html
------------How to Replace Spark Plugs?http://schematicsdiagram.blogspot.com/2011/07/how-to-replace-spark-plugs.html
-------------Car cranks, has spark but will not start?

http://howtobyme.blogspot.com/2011/12/car-crankshas-spark-but-will-not-start.html

------------------------
The spark plug firing order for car?http://schematicsdiagram.blogspot.com/2011/06/spark-plug-firing-order-for-car.html
----------How to gap spark plug ?http://technoanswers.blogspot.in/2012/02/how-to-gap-spark-plug-on-chevy-impala.html-----------Spark plug Replacing for?http://technoanswers.blogspot.in/2012/02/spark-plug-replacing-for-chevy-impala.html
-----------How to identify number one spark plug on the distributor cap?http://schematicsdiagram.blogspot.com/2011/12/how-to-identify-number-one-spark-plug.html
---------How does the spark plug wire go on the distributor cap?http://schematicsdiagram.blogspot.com/2011/12/how-does-spark-plug-wires-go-on.html
---------Spark plug Firing Order Diagram?http://schematicsdiagram.blogspot.com/2011/12/2006-suzuki-forenza-spark-plug-firing.html
-----------This will help.Thanks.

Misfire reasons.
Bad ignition coil (there are 3 of them), bad spark plug, bad spark plug wire (most common) defective fuel injector, intake manifold vacuum leak, low cylinder pressure due to burnt valves or scored cylinder walls.

Probably the ignition module under the three coil packs. It can be tested.

If the coil pack did not resolve the issue you are experiencing, then you may either have an injector issue, or a faulty PCM-powerterain control module, also known as the vehicle's computer.

depending on mileage, but possible tune-up could fix it. if already done then check ignition coil pack and ignition wires also spark plugs, check vacuum hoses for leaks or porous, last injectors clogged - use some techron fuel injector cleaner (wal-mart has them). have worked at G.M. dealership for over 15 years, saw that alot.

may be a bad module it is under the coils I think 3 and 6 are on the same coil so that would make both cyls not fire

You didnt mention having changed the spark plug wires, so that is another item that could be culprit as well. As well, it could be a coil pack that is not working properly.

I cannot recall at the moment if that model year uses coil on plugs or if it uses coil packs. Either way, if it uses a coil on plug set up, take the one for the #3 cylinder and move it to say #4 or anyone of your choice and see if the misfire follows

If it uses coil packs, there is likely one coil pack that controls two cylinders. In that case just swap the coil pack with an adjacent one and see if the problem follows. Pay attention to where the spark plug wires go because it will be an issue if you get them mixed up. You just swap the coil packs around.

I would, however, start with the spark plug wires if you have not changed them already.