hi everyone
got the 0304 code yesterday...changed the plug...switched the#4 injector with # 1 cylinder and still got the same code.....getting spark from coil...anybody got ideas on what to do next before I take it to the shop? BTW it has been missing when I started it in the mornings but cleared up after 2 or 3 minutes and was fine for the rest of the day. did that for about a week or so. Also the truck has 258000 on it./ last time I changed the plugs and wires at 192000 all OEM


Vic

 

This info is from OBD-II Trouble Codes - DTC Codes Car Repair

Causes

A code P0304 may mean that one or more of the following has happened:

• Faulty spark plug or wire
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector
• Burned exhaust valve
• Faulty catalytic converter(s)
• Running out of fuel
• Poor compression
• Defective computer

You might want to check all of the above to possibly find the problem and cure it.

 

How about the #1 COP, did you switch it with another one too?

 

dont have cop....coil packs

 

Okay then, same question, did you swap out the coil pack with the other side to see if there was any difference?

 

no i did not do that yet. but wouldnt more than 1 cylinder misfire if the coil pack was bad because it controls more than 1? today I am going to replace all plugs and wires just to eliminate the possibility of a bad wire or plug. then go from there.

 

Most of the time the fine wire making up the coil breaks or shorts causing the failure. In such a case multiple cylinders will be affected. In other cases you might get damage to just one portion of the coil assembly, such as a cracked tower that will only affect one cylinder.

BTW, have you swapped out the spark plug wire to see if that's the problem?

 

okay, changed the plugs and wires with oem and problem solved. While I had everything apart I also cleaned the MAF sensor, cleaned throttle body and checked all vacumm lines (found one slightly cracked). Put everything back together and it runs great. cost was 133.00 and 4 hours of my time but it was worth every bit of it.