#3 and #4 cylinder dead Please Help!

[BStewart]

1996 Sunfire 2.4L
Engine Code P0300

I am assuming the cylinder ID is 1234 starting from pass. side.

I thought maybe it was a bad ign. coil, but after taking all of that apart, I see that the two coils aren't split that way (#3 and #4 are on separate coils).

Engine runs rough and shakes like it's going to jump off the engine mounts. I can pull the plug from the #3 and #4 fuel injector at the same time and I get no change. If I unplug either the #1 or #2 fuel injector plug, the engine dies.

So what ties the #3 and #4 cylinder together? What could go bad to cause just those two to die.

Again, standing in front looking at engine, it's the two cylinders on the right that are dead.

Thanks for any help you can provide!

 

[melsg5]

This is a list of possible issues associated with PO300
•Faulty spark plugs or wires
•Faulty coil (pack)
•Faulty oxygen sensor(s)
•Faulty fuel injector(s)
•Burned exhaust valve
•Faulty catalytic converter(s)
•Stuck/blocked EGR valve / passages
•Faulty camshaft position sensor
•Defective computer

These are solutions
If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

 

[BStewart]

Thanks for the reply.

I've been through and checked most of that. I'm mainly looking for what could cause the #3 and #4 to die together as they are definitely the ones dead. Something has to tie just those two together right?

 

[melsg5]

a vacuum leak between the head and intake manifold on those 2 cylinders? try spraying carb cleaner or something similar along the mating surface to see if the idle changes