3.6 Codes issue & diagnoses

[ShadowsPapa]

If you had an oscilloscope, you can run a compression comparison using the scope and starter draw.
Pay attention to the starter draw on the scope - if there's an area where it's lower, you can make other connections to find the cylinder that's lower than the rest.

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[Lost1wing]

Thats kind of what I figured. Obviously not his fault.

So the question remains, where is a good place to buy/order a quality cam. Is the newer cam better? Can I swap the newer year cam and then drive it to dealer and have it flashed?

OEM parts are what I would go with. You're are not going to only replace the cam. Rockers and gaskets are needed too. I'm not sure of the backorder on those parts as of now. You may be looking and both sides depending on misfire counts.

If you are smelling fuel out the exhaust, you may need to take it in and have a scope put on it like ShadowsPapa was pointing out. You swapped the nbr one coil pack. Did you swap the plug too? Can you see if the connector on the fuel injector is on all of the way?

You can clear the pending codes but not the permanent code. The computer will have to like the repair for it to clear itself after a few drive cycles. If you cleared the codes and the p0301 pending code came back, then you didn’t fix the problem. If you didn’t clear the codes. You still would not know if you moved the issue until you run it a bit more to see if you get a p0303 pending code.

If it is running worse now. Recheck your connections and look closer at the pins.

 

[ShadowsPapa]

OEM parts are what I would go with. You're are not going to only replace the cam. Rockers and gaskets are needed too. I'm not sure of the backorder on those parts as of now. You may be looking and both sides depending on misfire counts.

If you are smelling fuel out the exhaust, you may need to take it in and have a scope put on it like ShadowsPapa was pointing out. You swapped the nbr one coil pack. Did you swap the plug too? Can you see if the connector on the fuel injector is on all of the way?

You can clear the pending codes but not the permanent code. The computer will have to like the repair for it to clear itself after a few drive cycles. If you cleared the codes and the p0301 pending code came back, then you didn’t fix the problem. If you didn’t clear the codes. You still would not know if you moved the issue until you run it a bit more to see if you get a p0303 pending code.

If it is running worse now. Recheck your connections and look closer at the pins.

This is where I like JSCAN - you can actually monitor the misfire count from the moment you start it, even while driving it.

But I realize - not everyone wants or needs or even would use a full shop of various tools and - if I had to add up the costs, I'd faint.

 

[Hootbro]

What is command circuit? how do I check that? Thanks

It is the injector pulse control circuit. Our system is ground side control by the PCM. You can take the connector off the #1 injector and look for 12VDC to chassis ground on Pin 2. Pin 1 goes to the PCM with the PCM providing the ground pulse. That is usually too quick for a standard multimeter and either a NOID LIGHT device needs to be use or a o-scope but unless you are electronically inclined, o-scope may be a bit out of your depth. You could still continuity check from Pin 1 to the PCM though to make sure that path is fine.

 

[Lost1wing]

I'm guessing the fuel injector is fine since you are smelling fuel from the exhaust. It could be stuck open but electrical test won't show that. You could pull the dip stick and check for fuel smell in the oil. If a fuel injector is stuck open, there's a good chance you would smell it in the oil. This would also make your problem get worse since the engine relies the oil to control things.

You could always bite the bullet and pull your right valve cover and have a peek. It will either shine some light on your problem or give you some breathing room knowing the cam looks good.

 

[Gladiatorguy]

My 2024 JT 3.6 with under 8,000 miles check engine light came on twice, but lasted less than a week. No drivability issues. Had the vehicle scanned both times at the local auto parts store. P0300 both times. Besides coil and plugs, the diagnosis mentioned contact points, reluctor assy, hall effect switch, crankshaft position sensor. Unrelated to ignition system, the intake plenum gasket was listed as a possible cause. Per the report, a failed gasket can cause coolant, oil, and vacuum leaks. Still waiting to get it into the dealer. Long waits for appointments around here.
My previous JT 3.6 would occasionally run very rough on a cold start, like only running on 3 cylinders. No check engine light and no codes set. Revving the engine cleared it up. Of course, the dealer couldn’t replicate the problem.

 

[Lost1wing]

My 2024 JT 3.6 with under 8,000 miles check engine light came on twice, but lasted less than a week. No drivability issues. Had the vehicle scanned both times at the local auto parts store. P0300 both times. Besides coil and plugs, the diagnosis mentioned contact points, reluctor assy, hall effect switch, crankshaft position sensor. Unrelated to ignition system, the intake plenum gasket was listed as a possible cause. Per the report, a failed gasket can cause coolant, oil, and vacuum leaks. Still waiting to get it into the dealer. Long waits for appointments around here.
My previous JT 3.6 would occasionally run very rough on a cold start, like only running on 3 cylinders. No check engine light and no codes set. Revving the engine cleared it up. Of course, the dealer couldn’t replicate the problem.

There are many possibilities. An intake leaking at nbr one could be his p0301 and disrupt the other cylinders to cause the p0300. What would cause the intake gasket to start leaking? Previous work, oil/water leaks or even and overtemp. He is hearing a ticking noise as well. That could be an exhaust leak or it could be a cam issue. I'm guess the 3.6l has more cam related issues than exhaust leaks.

You are still covered being a 24 and just a few miles, hopefully. I would not use the information given from the parts store for diagnoses. It appears they have a generic diag for many different years and variations.

 

[ShadowsPapa]

There are many possibilities. An intake leaking at nbr one could be his p0301 and disrupt the other cylinders to cause the p0300. What would cause the intake gasket to start leaking? Previous work, oil/water leaks or even and overtemp. He is hearing a ticking noise as well. That could be an exhaust leak or it could be a cam issue. I'm guess the 3.6l has more cam related issues than exhaust leaks.

You are still covered being a 24 and just a few miles, hopefully. I would not use the information given from the parts store for diagnoses. It appears they have a generic diag for many different years and variations.

Yeah, be wary of GENERIC parts store scans.
Some of those things listed went away 50 years ago.
All they can say is yeah, you have a misfire.
Ugh, parts stores........

 

[Lost1wing]

Yeah, be wary of GENERIC parts store scans.
Some of those things listed went away 50 years ago.
All they can say is yeah, you have a misfire.
Ugh, parts stores........

Hall effect sensor brought back memories. I was just learning about contact points and vacuum advance. Thought I knew it all when I pull the distributor cap off of a K-Car. Had to go back and figure that out and how to test.

 

[ShadowsPapa]

Hall effect sensor brought back memories. I was just learning about contact points and vacuum advance. Thought I knew it all when I pull the distributor cap off of a K-Car. Had to go back and figure that out and how to test.

You are likely familiar with the brass feeler gauge..........
I trained for the Plymouth Troubleshooting Contest in 1975 on the MOPAR electronics. It was 2 or 3 years old by then. There was the dual ballast resistor that was a common problem, and then you needed to be able to figure this out -

By that time, the shop I worked in was selling a "points elimination system" - you replaced the points with a light and sensor unit, and an interrupter with slots went under the rotor. When that piece turned where the sensor 'saw' the red light, it triggered the "brain box" as Andy called it back then (he was very old school, cut his teeth on cars and tractors in the 1950s) and you got a spark. You didn't have to change anything other than remove the points and condenser, lift the rotor and put the triggering wheel under the rotor.
I still have a couple of the parts in a cabinet somewhere. I put one of those on my 68 Javelin and never replaced points or condenser again. It was pretty reliable for an early after-market ignition system.


(Watch The Red Green Show for fun projects involving K cars )

 

[Lost1wing]

You are likely familiar with the brass feeler gauge..........
I trained for the Plymouth Troubleshooting Contest in 1975 on the MOPAR electronics. It was 2 or 3 years old by then. There was the dual ballast resistor that was a common problem, and then you needed to be able to figure this out -

By that time, the shop I worked in was selling a "points elimination system" - you replaced the points with a light and sensor unit, and an interrupter with slots went under the rotor. When that piece turned where the sensor 'saw' the red light, it triggered the "brain box" as Andy called it back then (he was very old school, cut his teeth on cars and tractors in the 1950s) and you got a spark. You didn't have to change anything other than remove the points and condenser, lift the rotor and put the triggering wheel under the rotor.
I still have a couple of the parts in a cabinet somewhere. I put one of those on my 68 Javelin and never replaced points or condenser again. It was pretty reliable for an early after-market ignition system.


(Watch The Red Green Show for fun projects involving K cars )

I will look at that tonight. I have to finish building a garage that I will never put a car into.

 

[ucijeepguy]

I'm guessing the fuel injector is fine since you are smelling fuel from the exhaust. It could be stuck open but electrical test won't show that. You could pull the dip stick and check for fuel smell in the oil. If a fuel injector is stuck open, there's a good chance you would smell it in the oil. This would also make your problem get worse since the engine relies the oil to control things.

You could always bite the bullet and pull your right valve cover and have a peek. It will either shine some light on your problem or give you some breathing room knowing the cam looks good.

I bought the parts expecting to need to swap camshafts. Now it’s torn apart and doesn’t look that bad. Passenger side.

 

[ucijeepguy]

Nope. As soon as I posted that I saw it.

 

[Hootbro]

Looks like the #3 cylinder cam lobes but had #1 misfire codes reporting. I am betting the shavings stuck to the cam reluctor wheel marks messed up the computer to think it was the #1 when it should have been the #3 reporting the misfire.

 

[ucijeepguy]

Looks like the #3 cylinder cam lobes but had #1 misfire codes reporting. I am betting the shavings stuck to the cam reluctor wheel marks messed up the computer to think it was the #1 when it should have been the #3 reporting the misfire.

I’ll take a better pic but there were 3-4 lobes worn down.

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