PO305 misfire 5.7L

[preston75052]

I have cylinder misfire PO305 is the code, I've swapped the coil pack and changed the plugs, and still the same code. From a performance perspective the truck is running fine, seems to have no issues but the code does keep coming back so definitely an issue.

I will say on cylinder "#5 far spark plug" right under the master cylinder there was some particles along the threads of the plug.

Does anyone have any idea what they maybe?

Thanks,

 

[Bloody_Knuckles]

https://www.engine-light-help.com/P0305-check-engine-light.html

 

[Fast69Mopar]

You could have a weak cylinder caused by valves that are not sealing properly.

Some easy diagnostics would help locate the issue but a scan tool that is capable of showing the misfire monitor is needed and a cylinder leak down tester as well.

You can rent the cylinder leak down tester from Auto Zone to determine if we have a mechanical issue related to cylinder #5.

If you have swapped the coils and plugs and the misfire stays with cylinder #5, try swapping fuel injectors to see if it follows the injector.

With your truck being a 2007 model, I would pull the valve cover on the left bank and inspect the valve springs to make sure you don't have a broken spring on #5.

 

[preston75052]

You could have a weak cylinder caused by valves that are not sealing properly.

Some easy diagnostics would help locate the issue but a scan tool that is capable of showing the misfire monitor is needed and a cylinder leak down tester as well.

You can rent the cylinder leak down tester from Auto Zone to determine if we have a mechanical issue related to cylinder #5.

If you have swapped the coils and plugs and the misfire stays with cylinder #5, try swapping fuel injectors to see if it follows the injector.

With your truck being a 2007 model, I would pull the valve cover on the left bank and inspect the valve springs to make sure you don't have a broken spring on #5.

Okay thank you for the reply. As far as the spark plug having like little particles/ chunks of debris on the threads. What could that be from ? It's something I've never seen in any car. My speculation would be something is broke.

 

[Fast69Mopar]

Okay thank you for the reply. As far as the spark plug having like little particles/ chunks of debris on the threads. What could that be from ? It's something I've never seen in any car. My speculation would be something is broke.

Can you post a pic of the spark plugs? Did it look like the debris was welded to the tip or the electrode from heat?

 

[Gohemi]

I had this too, followed by oil viscosity wrong, Knock sensor, and found harness down the frontside passenger to the knock sensors, etc was chafed to chassis. Cut it out, soldered in new section, volcano heat wrap and secured away from sharp frame.

 

[preston75052]

I had this too, followed by oil viscosity wrong, Knock sensor, and found harness down the frontside passenger to the knock sensors, etc was chafed to chassis. Cut it out, soldered in new section, volcano heat wrap and secured away from sharp frame.

Your saying a knock sensor was throwing the cylinder misfire? Which Cylinder? What did you repair or replace to fix your misfire?

I'm asking because after sending it to my mechanic he said it's not a spring after doing a compression test, and the code P0305 was a stored code
He cleared the code and it didn't come back for almost 3 weeks, the code is back now, but he mentioned to me that my oil viscosity was wrong which was weird to me bc I put whats recommended 5w20 mobile1 and always have in the past no problem.

Could you give me a little more detail on your troubleshoot and repair? I appreciate it!

 

[Fast69Mopar]

The knock sensors are bolted to the side of the block, below the cylinder head, in the middle of the block.

Check the wiring on each knock sensor to make sure it hasn't rubbed through the protective cover and exposed the wired to chafing.

 

[preston75052]

The knock sensors are bolted to the side of the block, below the cylinder head, in the middle of the block.

Check the wiring on each knock sensor to make sure it hasn't rubbed through the protective cover and exposed the wired to chafing.

I checked the wiring yesterday, could use some protective cover for sure. So could the knock sensor be the caused for throwing the misfire? I only located two, 1 on each side of the block, are there more?

Thanks

 

[Fast69Mopar]

I checked the wiring yesterday, could use some protective cover for sure. So could the knock sensor be the caused for throwing the misfire? I only located two, 1 on each side of the block, are there more?

Thanks

Only 2 knock sensors. One on each side. What we really need is a scan tool to watch the misfire monitor. I have seen knock sensors fail and cause funny issues with misfires and erratic timing.

I would unplug the knock sensors and see if the misfire returns or try and get your hands on a good scan tool to continue the diagnostics.

 

[preston75052]

Only 2 knock sensors. One on each side. What we really need is a scan tool to watch the misfire monitor. I have seen knock sensors fail and cause funny issues with misfires and erratic timing.

I would unplug the knock sensors and see if the misfire returns or try and get your hands on a good scan tool to continue the diagnostics.

I do have a scan tool, my i3 performance turner has a scanner. P0305 is the code. I've been through everything just about, plugs, coil , injector, mechanic did a compression test, now knock sensors been replaced. Truck runs great!

 

[Fast69Mopar]

I do have a scan tool, my i3 performance turner has a scanner. P0305 is the code. I've been through everything just about, plugs, coil , injector, mechanic did a compression test, now knock sensors been replaced. Truck runs great!

Excellent. Glad it's running better.

 

[preston75052]

Excellent. Glad it's running better.

No, what I'm saying is it's still giving me the P0305 misfire code and I'm at a lost! But I did find this, can you tell me what this is? It looks like my header burnt through the hoses.

 

[Fast69Mopar]

No, what I'm saying is it's still giving me the P0305 misfire code and I'm at a lost! But I did find this, can you tell me what this is? It looks like my header burnt through the hoses.

Sorry for misinterpreting your post. What you have in the pics is the EVAP Purge Solenoid and its vacuum and vapor hoses.

 

[preston75052]

Sorry for misinterpreting your post. What you have in the pics is the EVAP Purge Solenoid and its vacuum and vapor hoses.

This may be a far fetched question but do you think that could have anything to do with the misfire? Either way. What is my best option on finding the hoses?

Thanks

 

[Fast69Mopar]

This may be a far fetched question but do you think that could have anything to do with the misfire? Either way. What is my best option on finding the hoses?

Thanks

It could very well be related to the misfire because it can cause a lean condition. If the vacuum supply from the throttle body or intake manifold is properly connected to the purge solenoid, when the PCM commands the Purge Solenoid to pull a vacuum on the system it creates an open vacuum leak because the system is open from the burned-through lines instead of a closed system. It could very well cause a lean misfire.

With your scan tool, actuate the Purge Solenoid and watch engine vacuum when it opens and closes the solenoid. You will see engine vacuum drop by several inhg.

For the lines to the purge solenoid, I suggest hitting the local salvage yard or pick n' pull and pick up a set. I believe the line assembly is still available from Mopar. Do you see the black with white numbers parts tag attached to the line anywhere? If so, post the part number from the tag/label and I can look at the availability.

 

[preston75052]

It could very well be related to the misfire because it can cause a lean condition. If the vacuum supply from the throttle body or intake manifold is properly connected to the purge solenoid, when the PCM commands the Purge Solenoid to pull a vacuum on the system it creates an open vacuum leak because the system is open from the burned-through lines instead of a closed system. It could very well cause a lean misfire.

With your scan tool, actuate the Purge Solenoid and watch engine vacuum when it opens and closes the solenoid. You will see engine vacuum drop by several inhg.

For the lines to the purge solenoid, I suggest hitting the local salvage yard or pick n' pull and pick up a set. I believe the line assembly is still available from Mopar. Do you see the black with white numbers parts tag attached to the line anywhere? If so, post the part number from the tag/label and I can look at the availability.

Okay thank you for that info, super awesome of you.! I located the tag but its super faded and hard to read. But the only think I could come up with is these numbers and it kinda looks like the same part but not sure. Part # 52102940AC Also, shows to be for 02-03 instead of 07 ram. Is that a good lead for you to grab some info? I really appreciate the help!

 

[Fast69Mopar]

Okay thank you for that info, super awesome of you.! I located the tag but its super faded and hard to read. But the only think I could come up with is these numbers and it kinda looks like the same part but not sure. Part # 52102940AC Also, shows to be for 02-03 instead of 07 ram. Is that a good lead for you to grab some info? I really appreciate the help!

Based on my StarParts catalog and not having the last 9 digits of your VIN, the 2 part numbers I see that you need are below:

#1 52121035AG - Vacuum Emission Harness

#2 52110290AE - Vapor Purge Harness

 

[preston75052]

Based on my StarParts catalog and not having the last 9 digits of your VIN, the 2 part numbers I see that you need are below:

#1 52121035AG - Vacuum Emission Harness

#2 52110290AE - Vapor Purge Harness

View attachment 181520

Hey man, thanks for the info! I found the Vacuum Emission harness 52121035AG on ebay actually new but the person says its for 2003-2006 Which is odd considering the two different generation families by the years, usually its' 02-05 and 06-08. I would think if it's for 06 it would definitely be for my 2007

As for the Vapor Purge harness 52110290AE is no where to be found.