Like a flip of a switch car started running very rough like it was not running on all 4 cylinders . drove a half a mile & catalytic converter started smoking. Looked under car & cat was glowing orange. Took out cat & replaced with straight pipe. New plugs & wires engine still running very rough... Coil Pack?
SOURCE: 2003 Hyundai Accent with Engine skip...error code P0300 P0301
I have seen coil packs go bad on several Hyundai Accents, the coils will do exactly what they are supposed to (hence your check with an ohm meter), however, the coils short through the outer casing. Try running the car when it is dark out and spraying the coil packs with water. Listen for clicking and watch for arching from the coils to any metal around them. Look for abnormal detonation marks in the outer casing. My guess is you just need a set of new coils. If the Problem is worse in the rain then you have found your problem. Remember, If your car has been misfiring (as noted by the engine codes you listed), the EGR valve can become clogged and damage can be done to your catalytic converter as unburned fuel detonates inside it (keep an eye out for O2 codes in the future). Also, your new plugs can become fouled, be sure they are clean once you fix the problem. Checking your plugs can also be a useful indication of which cylinder is misbehaving.
It's the first cylinder on the motor from front(belts alternator) to back(transmission).
SOURCE: stalling and hesitation, all 4 cylinders misfiring, once warmed car seems to run ok
There are various questions to ask in order to help you.
When does it stall?
If it stalls when the AC of the car turns on, then this handy diagnostic article will help solve your problem:
http://yourhandymanzone.com/Your_Handyman_Zone_How_To_Pages_Vehicle_Car_Zone_Cars_Trucks_Vans_Engine_System_Engine_Stalls_When_AC_Turned_On.htm
Likely applicable to your situation--since you say the car runs fine when it is "warmed up"--when the car stalls because the engine is NOT warmed up and is otherwise cold, this handy diagnostic article will help solve your problem:
http://yourhandymanzone.com/Your_Handyman_Zone_How_To_Pages_Vehicle_Car_Zone_Cars_Trucks_Vans_Engine_System_Engine_Stalls_When_Cold.htm
And as to backfiring when you initially run your car, this handy article really helps in identifying the common causes of such a problem:
http://yourhandymanzone.com/Your_Handyman_Zone_How_To_Pages_Vehicle_Car_Zone_Cars_Trucks_Vans_Engine_System_Engine_Backfires.htm
This should help.
Good luck!
Brad
SOURCE: my 1997 hyudai accent has a missfire code on
Main causes of misfire would be loss of spark; the air/fuel mixture is too far out of balance to ignite; or loss of compression.
Loss of spark includes anything that
prevents coil voltage from jumping the electrode gap at the end of the
spark plug. Causes include worn, fouled or damaged spark plugs, bad wires
or even a cracked distributor cap. A weak coil or excessive rotor gas
inside a distributor would affect all cylinders, not just a single
cylinder.
"Lean misfire" can occur when the air/fuel
mixture is too lean (not enough gasoline in the mixture) to burn. This
can be caused by a dirty, clogged or inoperative fuel injector; air
leaks; or low fuel pressure because of a weak pump, restricted filter
or leaky pressure regulator.
Loss of compression means the cylinder
loses most of its air/fuel mixture before it can be ignited. The most
likely causes here are a leaky (burned) exhaust valve or a blown head
gasket. If two adjacent cylinders are misfiring, it's likely the head
gasket between them has failed. Also, if an engine is overheating or
losing coolant, it's likely the head gasket is the culprit.
You can isolate the weak cylinder by temporarily disconnecting each of the spark
plug wires, one at a time, while the engine is idling. When there's no
change in the idle speed, then you have pinpointed the weak cylinder.
Testimonial: "did the spark test found two plugs to be weak. what would be my next step. "
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Ok so here was the solution. The coil pack was bad & I also noticed that the firing order archived every where on the internet is WRONG. When I got the new coil pack I noticed the firing order was on the new coil pack.
I had no fire on cylinders 1 & 4 just like alot of others have listed a s well.
Put the new coil pack on. Made sure the firing order was correct & that was the end of the problem. worked like a charm car is running great.
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