03 hemi
had a broken exhaust valve spring on cylinder 6
threw a code p0306
and the truck wouldnt idle and if you took your foot off the gas it died out.

i cleared the codes
after a new vavle spring and all that mess, i got the 306 code gone, but truck still has code p0300

truck is only firing on cyl 7&8 and no spark on 1-6 !!!
i did the coil pack switch and new spark plugs and still only fire on 7&8 so i know my coils are good

good comp on all cylinders now
so what do i look at next? the cylinders that arent firing are getting fuel too cause when i pull the plugs they are all wet with gas

 

check fuses

 

P0300 has nothing to do with fuses.

That is Random/Multiple Cylinder Misfire Detected and could be anything and nothing at the same time.

Look here for more info

B/C/P/U 2004-2006 codes in full details from AllData

 

i know it doesnt have to do with fuses. I never stated that, i am just not getting fire on every cylinder except 7&8....and i checked my coils all are good, and all cylinders are getting fuel.

 

How do you know you are getting no fire on those cylinders? Did you take the coil and plug out and literally ground the plug and have someone try to start the engine to check for a visual spark? Because P0300 does not mean you have no spark.

Since you have 2 plugs per cylinder and since the top mounted coil fires only one of the plugs and another opposite coil fires another plug, are both plugs wet or just one?

The next thing I would check it the wiring connections itself as for the wire because the ASD relay controls when the coils fire and the PCM controls the ASD relay by sending a particular pulsed ground though the ASD to fire a particular coil.

5.7L V-8 ENGINE

For additional information, also refer to Ignition Coil Description and Operation.

The 5.7L V-8 engine is equipped with 16 spark plugs. Two plugs are used for each cylinder. The 5.7L is also equipped with 8 separate and independent ignition coils. The one-piece coil bolts directly to the cylinder head cover and attaches the coils secondary output terminal directly to a spark plug using a rubber boot seal. Each coil is also equipped with a second output terminal. This second terminal connects a conventional spark plug cable directly to a spark plug on the opposite cylinder bank. A separate primary electrical connector is used for each coil.

Eight conventional spark plug cables are used with the 5.7L. These cables connect a coil on one cylinder bank, directly to a spark plug on the opposite cylinder bank. The cables are placed and routed in a special plastic loom to keep them separated. This loom is clipped to the intake manifold. To prevent a missmatch of cables, a corresponding spark plug / coil number is displayed on each plug cable: 1/6, 2/3, 4/7 and 5/8. These numbers can also be found on the top of the intake manifold to the right of the throttle body (Fig. 1).

Two knock sensors (one for each cylinder bank) are used to help control spark knock.

The 5.7L engine will not use a conventional distributor.

The ignition system consists of:
² 16 Spark Plugs (2 per cylinder)
² 8 Separate, Dual-Secondary Output, Ignition Coils
² 2 Knock Sensors
² 8 Secondary Ignition Cables
² Powertrain Control Module (PCM)
² Also to be considered part of the ignition system are certain inputs from the Crankshaft Position, Camshaft Position, Throttle Position, 2 knock and MAP Sensors

 

yeah we know its not firing because the coils are not getting a ground trigger, we pulled the harness out to make sure the harness didnt have a break at the power splices and wasnt self grounding, the only 2 plugs that are getting a power AND grand are 7 and 8, the others just get power but no ground signal from the pcm would triggers them to heat up and fire. So as for now, i know i have 8 good coils, and also has a good harness, and new plugs and wires. they rnt getting signal to turn on. So what can it be ? the pcm bad???? it was replaced under warranty at 50k due to moister. But can it be bad again ? what else do i look at ? i need this truck fixed asap !!!

 

did you try resetting the pcm, might have to get a dealer to do a hard reset

 

if you are firing on 2 out of 6 coils then it would be my assumption the ASD relay is obviously good and working or no coils would fire. This would lead back to the PCM

Here are some pages from the Srvc Man.

 

my buddy works at the local dodge as a tech, is bringing home the drb to diag the truck and pcm tonight. If i do a hard reset ( would that be un hoooking the battery ? ) cause i have a programmer i have cleared codes with already and didnt fix it. But i havent reset the computer yet. Should i unhook it and wait a lil bit ? before i hook it back up n try again

 

If he has a DRBIII or Starscan tool then he can likely plug it in and tell you exactly what the issues are.

Let us know what he says.