[Mopower71]

2011 Charger rt awd
This charger is getting the best of me.
#3 cylinder misfire. P0303 .
New coil pack, spark plugs and a new injector.
Still getting an intermittent misfire on #3 cylinder.
It's fine just driving around. Get on it hard and it will start missing, but not all the time. Will continue to misfire for a little while, then it clears up.

Is possible one of the lifters is collapsing then pumping back up? I hear no strange noises when it is misfiring.
I'm at a loss now.
My son is headed back up to college in about 2 weeks and I need to get this sorted out.

 

[gapi]

Prepare for a situation when its missing and you can shut off during it. Pull the plugs and show us photos.
If you are lucky its a valve stem seal. The plugs will be black or glazed. Take good focused pics. Wipe finger and palm oils off the lenses. Could be a wire to the coil or injector.
Unlucky? Cam lobe & lifter wearing down, or rings.

 

[Mopower71]

Prepare for a situation when its missing and you can shut off during it. Pull the plugs and show us photos.
If you are lucky its a valve stem seal. The plugs will be black or glazed. Take good focused pics. Wipe finger and palm oils off the lenses. Could be a wire to the coil or injector.
Unlucky? Cam lobe & lifter wearing down, or rings.

 

[Mopower71]

Prepare for a situation when its missing and you can shut off during it. Pull the plugs and show us photos.
If you are lucky its a valve stem seal. The plugs will be black or glazed. Take good focused pics. Wipe finger and palm oils off the lenses. Could be a wire to the coil or injector.
Unlucky? Cam lobe & lifter wearing down, or rings.

These plugs were new less than 50 miles, just pulled them out , was misfiring before shutdown

 

[Mopower71]

Prepare for a situation when its missing and you can shut off during it. Pull the plugs and show us photos.
If you are lucky its a valve stem seal. The plugs will be black or glazed. Take good focused pics. Wipe finger and palm oils off the lenses. Could be a wire to the coil or injector.
Unlucky? Cam lobe & lifter wearing down, or rings.

These are the ones I pulled out on Thursday morning. Car was shut down and not run after the misfire started.

 

[CE9311]

 

[Mopower71]

View attachment 126651

Nooooooooo

 

[gapi]

WoW, pretty clean, almost wicked lean.

You have not mentioned rocker arm noise. AKA the tick.
So no oil.
If not electrical then perhaps cam lifter or just lifter if lucky.
You can pull the valve cover and bump start the engine observing the springs to see if they all compress all the way. The coils will all almost touch when the cam pushes the lifter to (TDC) top dead center.

You pull the fuel pump relay and spin her several rotations to pump the oil up on a cold engine and then bump the suspected around to TDC as best you can observe.

On a severe case like the pic CE9311 posted it you will be able to plainly see the lack of rocker movement.

My bump starter

 

[Mopower71]

WoW, pretty clean, almost wicked lean.

You have not mentioned rocker arm noise. AKA the tick.
So no oil.
If not electrical then perhaps cam lifter or just lifter if lucky.
You can pull the valve cover and bump start the engine observing the springs to see if they all compress all the way. The coils will all almost touch when the cam pushes the lifter to (TDC) top dead center.

You pull the fuel pump relay and spin her several rotations to pump the oil up on a cold engine and then bump the suspected around to TDC as best you can observe.

On a severe case like the pic CE9311 posted it you will be able to plainly see the lack of rocker movement.

My bump starter

View attachment 126652

View attachment 126653

Thanks gapi.
I had to run and get a new compression gauge. Not trusting mine right now. #3 read 55psi and #5 was 100. Restarted car after and it runs fine. With 55 psi it should have a dead miss.
I like the rocker switch trick for the starter .

It does not have any valve trian noise, even when it is misfiring.
What is the other wire for with the fuse?

 

[Mopower71]

This is #1 front plug.

WoW, pretty clean, almost wicked lean.

You have not mentioned rocker arm noise. AKA the tick.
So no oil.
If not electrical then perhaps cam lifter or just lifter if lucky.
You can pull the valve cover and bump start the engine observing the springs to see if they all compress all the way. The coils will all almost touch when the cam pushes the lifter to (TDC) top dead center.

You pull the fuel pump relay and spin her several rotations to pump the oil up on a cold engine and then bump the suspected around to TDC as best you can observe.

On a severe case like the pic CE9311 posted it you will be able to plainly see the lack of rocker movement.

My bump starter

View attachment 126652

View attachment 126653

This is the compression, the engine was Cold, and wot. Just to be consistent I let it go through 5 compression strokes on each cylinder.

 

[Mopower71]

Should I still be pulling a valve cover, or digging into the wiring, do the compression test hot?
I'm thinking hot compression but I would think I would hear the rocker clattering if the lifter collapsed when hot.

 

[Mopower71]

Compression test hot wot on #3 was 190, #5 was also 190.
This is after driving it, and it was missing when I pulled into the driveway, pulled the 2 coil packs and plugs and did the test

 

[CE9311]

Pull Valve cover and measure rocker arm throw on effect cylinder vs fine cylinder.

 

[Mopower71]

Pull Valve cover and measure rocker arm throw on effect cylinder vs fine cylinder.

I'm at that point right now.
Have the valve cover off. Rockers seem tight up and down. No excessive slop, but I'm unsure where on the cam lobe this cylinder is right now.
Engine is still hot from driving it, so I'm going to let it cool , then start rotating it.
Thanks for the help

 

[Mopower71]

Charger rockers

youtube.com

Pull Valve cover and measure rocker arm throw on effect cylinder vs fine cylinder.

 

[CE9311]

Charger rockers

youtube.com

So as I was saying........

 

[Mopower71]

So as I was saying........

View attachment 126681

Ugh.

 

[Mopower71]

So as I was saying........

View attachment 126681

How much fun is it to get the cam out?

 

[CE9311]

How much fun is it to get the cam out?

Time consuming. Heads come off, lifter pulled. Just take your time mark where everything goes. I used a sharpie. The pushrods specifically. When pulling the cam using the Cam bolt threaded in with a pair of visegrips tightly clamped to it really helps removal and instalaltion. When reinstalling Lube it up, and then lube it some more. And if it looks like enough, add some more. Highly suggested to remove oil pan and clean it and the oil pump screen. As well as pull the MDS and VCT solenoids in the valley to inspect the screens for flakes.

I removed radiator, had car jacked up on front so condenser could be lowered while still hooked up.

Here are a few photos I managed to take during my work.

I HIGHLY suggest if you ever wanted to add shorties or any exhaust manifolds NOW is the time with heads removed.

Last note, just personal- I ran the car through few heat cycles (fan kicking on and off) shut down and changed the oil. I then drove 500 miles and changed the oil again to make sure any repair containment were flushed or filtered out.

 

[340X]

Anytime compression is below 120 psi, you will have a misfire. Burnt valves from running hot or lifters not collapsing will be around 90 psi if not terrible. 60 psi if pretty bad or leaking head gasket. That could be your issue, leaking head gasket. Oreillys has what's called a "block tester" you can rent. It basically sniffs fumes/gases in the radiator/coolant tank to see if theres any combustion leaking into the system.
I had one that ran fine, didnt overheat unless the AC was on running down the highway. Checked the system. There is a blue liquid that you use. If you have combustion gases present it turns yellow. If it turns blue/green you have a leak also. That's kind of the iffy part especially for the first time using it. I went ahead and pulled the heads. Sure enough, both head gaskets were blown. Not badly, but just enough to matter under heavy load. Head gaskets had just been put on recently but not correctly. Copper gasket spray was used on both sides to keep from having to surface the heads. Had another car some "mechanic" used gray silicone on the head gaskets.
You never know what has been previously done to the car unless you are the only owner and the only person that has ever worked on the car. Unfortunately, not everyone is ethical or experienced as they should be to do a particular job.
You could try having a tuner turn off the MDS to see if it makes a difference. Not changing oil properly could cause lifters not activating properly. I've had good luck with running Rotella T6 for an oil change to really clean an engine up internally. If it's really bad, you may want to do it twice. Cam phasers are very sensitive to cleanliness. That could be another problem. An oil change would be a cheap and easy fix if it works.
I'd also do a cold compression test again to check cold operation. 3 compression strokes should be plenty to test pressure. 5 strokes could be camouflaging a weak cylinder.