I replaced all the spark plugs, replaced the coil on cylinder 4, and the car went back to normal. It was shaking pretty bad especially when you gave it gas. After the replacing the above mentioned parts the car drove fine for 1 night, this morning as i was getting to work it started going in and out of the shakiness. Finally i get to work, and it was full blown shaking again, and the P0304 code is back. Does any one have any helpful advice on this issue?? Please Help.

 

Can it be the injector in cylinder 4? It has a new coil and new spark plug..cannot think of anything else it can be...

 

fuel injector or cylinder damage (fuel injector is more likely) Do you or anyone you know have a cipher cable? If so I would say do a power balance test. If it is the injector, then when you "kill" cylinder 4 the idle won't change. If the idle is bad enough when you kill any other injector it may stall (normal)

 

2 add'l things you can check:
1) Make sure you have not swapped the connectors for plug # 4 and 6 by accident, a very common mistake (however; doing this would cause a misfire at all times and not just randomly)
2) Do a visual check of the connector for plug 4 and make sure it isn't broken


I know both plug and coil pack are new, but its also worth testing them by swapping them with plug 2/6 to see if the code jump. You might have shorted the new coil pack due to a faulty harness...

 

Thanks a lot! I will look into the plugs and see if they seem corroded or broken , although i do not think that is the issue. I am hoping it is not the injector, but it seems it can be that. But you are right about the coi pack..it might be getting shorted. The code continues to indicate cylinder 4 has a problem.

 

New plug and coil eh.
And still the issue.
Check the wires on the coil to make sure you have the correct signal/power going to it.
If you don't have the specs of power, measure a known good working coil for signal/power readings.
If cyl 4 has the same readings as the known good cyl, then check the injector. Again do the same thing. Check known good injector wires& check cyl 4. Let us know.

 

Thanks buddy, I did all that and everything was fine, it ends up that my ECU needed to be re-programmed. once i had that done now the car is running perfect again. I had changed the mass flow sensor and the entire throttle body, and i heard that you need to do these re-learn procedures. I never did those, so we just re-programmed the ecu and wala! I need a few days of driving it to see that the problem stays away. I will keep y'all posted. Again I greatly appreciate you guys! I am rather new on here, and already have been helped more than once!

 

good job!
and no problem.

 

I despise electrical problems but glad you got it figured out

 

So the car was fine and now the problem returns one day later. I am being told to replace the coil pack again. Cylinder 4 misfire code P0304 is back. my injectors are all good, ground is good, so another coil and we will see how long it lasts. I am at the point of getting rid of this car....

 

Are you doing this on your own or getting it done by a mechanic?

If you are doing this by yourself, then don't waste money on a new coil until you have confirmed that it is broken. Swap the coil with another cylinder and if the code doesn't jump from 0304 to 0302/6 (whichever one you swap it with) then you can be assured that the coil is NOT the issue.

I think it might be the harness/connector that you plug the coil into.

 

So if it is the plug, how do I get another plug? I hear the entire car would need to be re-wired and that can be costly...I wanna blow this car up..nice car, too many headaches...

 

If you are good at wiring you can fix the current one (as long as the actual connector piece isn't fried.

I don't think the coil connectors are attached to the entire wire harness. I am sure they can be detached somewhere and so you will need that piece. Check the classifieds under accessories and electrical. There are usually people selling a bunch of harnesses and you might find one cheap.

Edit: Found a thread on how someone fixed a coilpack frying problem
https://g35driver.com/forums/engine-...agnostics.html

May be it's your grounding?