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Discussion Starter #1
p0300.. the famous misfire :(...
Charger 06 sxt 3.5L

First time, I had 2 codes.. misfire cyl 1 and random misfire. I've changed the coil of cyl 1, with 6 new spark plug.. same problem..

At the beginning.. I'll see the code appear.. but no shake, nothing.. the car have all his power.

2 gaz tank later (with one injector cleaner)..same prob..but now, I can feel than more than one cylinder miss.. fast and repetitive little miss (with a fast little shaking).. samething on the cruise ctrl on highway.

I can see the code appear in acceleration, or when my feet don't touch the pedal.. Never see on park (idle). (just random misfire appear now)

Temp. of both calatytic are equals.

The car never stall.. but harder on gaz.. 75 miles less with 1 tank

If it's a gaz pressure problem.. I'll didn't had power during acceleration.. but my accelerations are good..

Someone have an idea ?...

I can check the compression.. but the problem is not always present..

thank you very much!.

If you have a possible solution, you can email me @ [email protected]
 

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Here is alist of things you can check for the dreaded PO300.

Common Problems that Trigger the P0300 code:

Worn out Spark Plugs, Ignition Wires, Ignition Coil(s), Distributor Cap and Rotor (where applicable)
Incorrect Ignition Timing
Vacuum Leak(s)
Low or Weak Fuel Pressure
Improperly functioning EGR System
Defective Mass Air Flow Sensor (MAF)

Defective Crankshaft and/or Camshaft Sensor
Defective Throttle Position Sensor
Mechanical Engine Problems i.e Low Compression, Leaking Head Gasket(s) or Valve Problems
Common Misdiagnosis:
Fuel Injectors
Oxygen Sensor(s)
Power Train/Drive Problems
 

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Here is alist of things you can check for the dreaded PO300.

Common Problems that Trigger the P0300 code:

Worn out Spark Plugs, Ignition Wires, Ignition Coil(s), Distributor Cap and Rotor (where applicable)
Incorrect Ignition Timing
Vacuum Leak(s)
Low or Weak Fuel Pressure
Improperly functioning EGR System
Defective Mass Air Flow Sensor (MAF)

Defective Crankshaft and/or Camshaft Sensor
Defective Throttle Position Sensor
Mechanical Engine Problems i.e Low Compression, Leaking Head Gasket(s) or Valve Problems
Common Misdiagnosis:
Fuel Injectors
Oxygen Sensor(s)
Power Train/Drive Problems
all that and bad gas also. I reccommend using 89 all the time!!!!!!!!!!!!!!!!! change gas station.
 

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Discussion Starter #4
about gaz

I've always tank only with super (91 octanes) sometime 94.. but never had a problem with that (75 000 miles done now)
 

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Discussion Starter #5
I found a TSB about p0300.. for flashing the PCM (Powertrain Control Module)...

Does this procedure solve the problem for someone?

If my car isn't on warranty, Do I have to pay for flashing de pcm?
 

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Same issue with my 2007 SE 3.5L HO. Misfire on cyl 5. Took it to dealership and they couldn't recreate the misfire. They've had it for a week and found no cause :( warranty is up in 200 miles...
 

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My 2010 Charger 3.5 V6 had a #4 cylinder misfire changed all spark plugs, did not fix, swaped coil packs between #4 and #2 cylinders now get random misfire and idles rough. Anybody got any ideas also changed #4 cylinder coil pack
 

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Just a thought and might have no real connection:

Are you losing any coolant or finding fouled oil?
My old car (Pontiac Grand Am) would misfire on occasion; it was due to a intake / head gasket leak.
The Temperature would spike causing this to happen.

Carbon build up?


My 2010 Charger 3.5 V6 had a #4 cylinder misfire changed all spark plugs, did not fix, swaped coil packs between #4 and #2 cylinders now get random misfire and idles rough. Anybody got any ideas also changed #4 cylinder coil pack
 

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I had a random misfire code p300 and a 158 the bank 2 , number 2 o2 sensor high voltage and the car would idle fine but soon as it was in gear it was running rough and also take off it wouldn't go past 40 and then all of a sudden take off. I changed the 02 sensor and still same problem. i then changed all the plugs and same thing again, was looking all over the net and someone said the same thing that can cause this was a vacuum leak. i used a rubber hose held up to my ear and started looking/listening around. found the gasket between the throttle body and the intake was leaking, pull it and sanded the throttle body surface with 1200 wet sanding paper so i didnt change the surface. than put back on and car ran fine, i could still hear a leak so i ordered a new gasket and replaced it today and i can hear the leak still but not as bad, i took for a drive and no codes, no miss fire, no nothing, runs perfect now. i sure hope this helps someone because iv been trying to fix my issue for 3 weeks and if someone said about a vacuum leak and it was their throttle body gasket i would of checked it right away. anyways good luck and i hope i can help someone out because i was starting to get worried what was going on.
 

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I had a random misfire code p300 and a 158 the bank 2 , number 2 o2 sensor high voltage and the car would idle fine but soon as it was in gear it was running rough and also take off it wouldn't go past 40 and then all of a sudden take off. I changed the 02 sensor and still same problem. i then changed all the plugs and same thing again, was looking all over the net and someone said the same thing that can cause this was a vacuum leak. i used a rubber hose held up to my ear and started looking/listening around. found the gasket between the throttle body and the intake was leaking, pull it and sanded the throttle body surface with 1200 wet sanding paper so i didnt change the surface. than put back on and car ran fine, i could still hear a leak so i ordered a new gasket and replaced it today and i can hear the leak still but not as bad, i took for a drive and no codes, no miss fire, no nothing, runs perfect now. i sure hope this helps someone because iv been trying to fix my issue for 3 weeks and if someone said about a vacuum leak and it was their throttle body gasket i would of checked it right away. anyways good luck and i hope i can help someone out because i was starting to get worried what was going on.
Thanks for posting your repair, dodgeonetimer! It's always appreciated! :bigthumb:
 
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