02 chevy cavalier I've replaced the whole ignition system and I'm still getting code p0304 and it's not a cracked head or head gasket I'm stumped cause it runs s and drives pretty good help

 

The Chevrolet Cavalier was a great sub-compact. I know as I owned two and Chevy built it for 23 years. You might want to compression test it, but I'll wager it is these cuases:

P0304 CHEVROLET code possible causes

• Faulty spark plug 4
• Clogged or faulty fuel injector 4
• Faulty ignition coil 4
• Fuel injector 4 harness is open or shorted
• Fuel injector 4 circuit poor electrical connection
• Ignition coil 4 harness is open or shorted
• Ignition coil 4 circuit poor electrical connection
• Insufficient cylinder 4 compression
• Incorrect fuel pressure
• Intake air leak
• ECM is defective

Also you may have too much carbon on your valves. Might want to drop some Techron Complete in your fuel tank.

I did have to replace the coil pack, after recieving the dreaded P0300 code on one of my 2.2 liter Cavaliers.Easy fix.














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did you check for spark on cylinder 4. Spark testers are $10 this should be the first step.
check #4 injector for fuel leak at the electrical connector. If dry, you are good. run the vehicle and listen to the injector with a mechanics stethoscope,....you should hear it click as it opens and closes.
next step is to do a compression check. if compression is ok....replace the injector

 

Hi maybe my experince may help, Had a 2006 S10 with six cyl.. No 1 cyl would go to miss fire after milisec of running. Replace plugs and wires. Put a scope into
plug hole and found hardend deposits on the intake valve.. After many intake, valve chemcial cleaning finally broke the deposits away and valve seated.