Question about 2000 Daewoo Nubira
P0304 in most cases for cylinder # 4. There are usually 4 reasons that this codes sets. Inmost cases the cause is a faulty fuel injector, a faulty spark plug, a faulty spark plug wire and a faulty coil. I start on the easiest stuff like checking the spark plug and wire. If you can check to make sure you are getting good spark through the cable. If not using an ohm meter check the resistance of the cable/wire. If they are OEM wires the should be above 30,000 ohms. You can also check all the other wires and if there is a big difference in the # 4 wire, then you have a bad cable/wire. If you are getting bad spark and the cable is then most likely the coil is bad. next you will want to chek the injector for that cylinder. This is more detailed but have found it to be the most common cause of P0304. If the vehicle is running poorly, while the engine is running you cab disconnect the injector for that cylinder. If there is no real noticeable change then most likely it does have to do with an injector fault but that doesn't always mean that you have a faulty injector cause there are many other factors that can cause this other than the injector itself and this test isn't the most reliable. You will need some testing equipment in order to fully diagnose this test and/or the injector. I'll be happy to help with those tests but it is quite detailed and to much to write on here. If you are in need of these tests, feel free to email me directly at firstname.lastname@example.org and I'll be happy to email them to you. You will at least need a test light and if possible an injector test light but are able to do without that. If you don't have that noticeable change when unplgging that injector connector, you can start by making sure you have power to that injector. the way your system works is that each injector has constant power at the injector through the pink wire while the ignition is on. The vehicles computer (PCM) gets readings from other sensors and it's supposed to send a negative "pulse" through the other wire (the solid black wire, the light orange wire with a black stripe, and the pink and light blue wire both also having a black stripe). This "pulse" completes the circuit and turns that injector on which in turn sprays out gas at that point. So check for power at that injector as well. As you amy have guessed. I've done this before so I hope I've been able to help and good luck.
Posted on May 02, 2013
Could be spark plug,coil,wire.
Posted on May 02, 2013
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Posted on Jan 02, 2017
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