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Followup To
It's a Accent 1.5 g I beleive How do i check the coils?
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Followup To
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my car starts but you can't give it any gas till warm today the exhaust was cherry red a couple of feet off the manifold. It also had know power even when driving, and ran reel ruff when starting. Can you help I'm starting to think it's a oxygen sensor? Thanks
Answer -
If your car is running rough, I'd suspect a misfire. That would also explain a red exhaust due to the unburned fuel there.
What year and model car do you have? Is your check engine lamp on? Is your check engine lamp flashing? It is a 2000 Hyundai and the answer to the other two questions is yes! I would be hard press to believe it is a miss fire! When it was so hot you could light a thousand cigerets of of it!
Answer -
If your check engine lamp is flashing, then you have a serious misfire problem. The reason the exhaust was so hot is that the fuel was burning up in the exhaust.
First check the spark plugs, plug wires and ignition coil. These are the primary causes of misfires. Considering how hot you've gotten the exhaust, it's also possible that you've ruined your catalytic converter. If you need guidance with checking the ignition components, let me know what you'll need assistance with. Also, it may help to know what model Hyundai you have (Accent, Elantra, Sonata, or Tiburon).
AnswerIf you have access to a code reader, start there. The trouble codes stored in your ECM (engine control module) will identify the misfiring cylinder(s). The code P030x represents a misfire on cylinder number x, with P0300 being a random misfire.
To start diagnosing the misfire, remove the ignition wires from each plug, and set them back on so they're touching but not clipped back securely into place on the plug. Now start the engine. Wearing insulating gloves, gradually pull the #1 wire off the plug. If it begins arcing out the side of the wire or at the coil, then you have a problem where the arcing is occurring. If there is no arc out the end of the wire onto the top of the plug when you begin to pull the wire off, then there's an issue with the spark not reaching the end of the wire. If you don't see any arcing at all anywhere, then this would most frequently be caused by a bad coil, but there are other possibilities. If the engine doesn't run rougher or stall when you get the wire far enough away that the spark won't jump to the plug, then you have a misfire on this cylinder. Presuming you've got arcing out the end of the wire as you pull it off, you should then suspect a spark plug issue. Place the wire back on the plug and repeat with the remaining cylinders. When you're done doing this, remove all the spark plugs and visually inspect them for wear and carbon tracking down the sides of the ceramic. Any of these can cause a misfire as well.
As for the easiest way to tell whether a coil is firing, get a known good plug and wire. Remove one of the wires from the coil and install your test plug and wire and lay the metal portion of the side of the park plug on the plenum or something else metal that will act as a ground, but don't use the fuel rail or the fuel line as this would maybe cause some unintended fireworks. Then crank the engine and see if your test plug fires. If not, then you know the coil isn't firing (but not necessarily that the coil is the problem). On the other hand, if you get spark from the plug, you know that the coil is functioning normally.
