Fuel injector question- OK at idle only

[Darthomas]

First time driving a car thats not 40 or 50
years old. Have 2013 Charger ex Michigan State Police 5.7L hemi where cyl 2 misfire is dependable and repeatable.
Been driving it two weeks now, not a sticking valve, new plugs on cyl 2 and coilpack. 28 mpg when I baby it, but only pulling on 7 under load.
Misfire may clear and run smooth while I wait at idle at a traffic light, all 8.
Turning off the engine and restarting has given all 8 injectors 100% of the time.
Torquing up the engine with the brakes on to about 2500 brings it on.
Restarting clears it .
Pulling #2 fuel injector plug while it's "doing it" makes no difference.
Plugging it back in makes no difference, I don't hear it firing.
Restarting the engine and pulling the plug on the injector gives regular on/off results in rpm and I can hear the injector on vs off.
So is it just this injector is "OK" at idle fuel pressure only and cannot overcome higher pressure @ higher rpms, or the coil is weak (partially shorted) and cannot follow higher speeds resulting in misfire.....
yes I have a voltmeter 2 feet away and haven't measured the coil(s) to compare yet, because I troubleshoot by some kind of osmosis.
I'm sitting here at smooth idle for 29 min but I could make this motor miss in 10 seconds, and could clear it in 10 seconds.
Engine has 7723 hours, 5092 idling.
Got the injector crud out, and a lot of crankcase varnish via Seafoam before oil chg. As I am an electrical engineer I am declaring I think I have a partly shorted solenoid, which can only keep up with slower pulses and/
or lower fuel rail pressures.
I wecome your consideration.
I

 

[Force Fed Mopar]

Bad injector would be my guess also. However a '13 should have the MDS system on it also, could be one of the solenoids for that messing up.

 

[texas69bee]

I'm guessing injector as well but you could eliminate a lot of work and take it to some place like Autozone and get a free diagnostic error code message.
Does the service engine soon light ever come on?

 

[Ranger16]

Swap the injector with another cylinder and see if the problem follows it.

 

[Darthomas]

Perhaps I'll swap one tomorrow.
I have a new one coming monday.
I did measure the coil, cylinder 4 and 6
were 14.6 ohms, the suspect is 14.3.
I was afraid it might be one of the cylinder deactivation solenoids, but it's on a cylinder that doesn't get turned off.
Always gives P0302, I bought a reader.

 

[texas69bee]

Gap on plug or bad plug?
http://www.engine-codes.com/p0302_dodge.html

 

[Darthomas]

New plugs in that cylinder.
No change.

 

[Darthomas]

New injector, no change.
Mesaured voltage to injector solenoid, and discovered the pulse is low voltage and weak when the misfireing s occurring.
I believe I have a bad solder joint on the output for cyl 2 on the engine control management box.
Ordered a new one today.
Mamy hours of hot idling has likely caused a solder joint to crystallize.

 

[Darthomas]

Dealer installing new engine control module now (fingers crossed).

 

[Darthomas]

50% better, but no cure.
No more missing fuel pulses, but maybe a partly sticky valve still happening.
Exhaust, by the sound of it.
Next is the Sea-Foam smokescreen treatment.
I'll need to head 'way out into the corn and beans for that. Maybe tomorrow.

This is what you get when you buy a car at half the customary price.
You know you are buying someone else's headache, at an undefined discount.
It's a game of poker.
Maybe I'll need a new head.
I'm still about $9000 ahead of average, so even a total new motor would be a good deal.
At least I know the car was beaten as necessary by state police and rigorously maintained, not just some unaccountable dufus.

 

[Darthomas]

Still thinking #2 cyl exhaust valve is not "stuck" but "sticky", and when 1400 rpm is reached, the mass/acceleration puts the valve into a spot on the stem with heavy carbon, and the misfire starts.
Stills clears completely 100% of the time on restart, and getting quicker at idle.
Added a LOT of Marvel Mystery Oil to the gas, and 12 oz in the oil.
Either it's getting better a tiny amount, or I'm fooling myself.
My machinist father always had a top-oil feeder, or added MMO to the gas ......religiously.

 

[Force Fed Mopar]

Could be a bad lifter maybe?

 

[Darthomas]

Could be a bad lifter maybe?

Comes and goes..I am still thinking carbon making no 2 exh sticky.
Just drowned out motor with sea foam into brake vacuum line, and waiting 30 minutes to make the smoke show in the industrial neighborhoood.17 more minutes....

 

[Darthomas]

Waiting till 02:00 for smoke show.
Fingers crossed.

 

[Darthomas]

Here goes.

 

[Darthomas]

Much better, but did not completely cure the stickiness.
Will do more treatments.
Definitely woke up a few more horses.

 

[Force Fed Mopar]

Pour Seafoam in the oil before the next oil change to clean the lifters and heads out.

 

[Darthomas]

Pour Seafoam in the oil before the next oil change to clean the lifters and heads out.

Did that.
Added more along with new oil.
Have done 2 smoke shows and it still seems to get a little better all along, but it's still sticking on cyl 2.
I'll just keep doing the smoke shows for a while.

 

[Cranky]

With all the smoke do harm to the o2 sensors or the cat? I've done the smoke show before with my 95 Dakota. I run a straight pipe on it but the o2 is still in. So far so good. Did you buy the car at a police auction and was it one of the newer cars being sold?

 

[Darthomas]

Hasn't seemed to hurt them, and my research hasn't turned up any accounts of that.
It was sold at auction to a used car dealer near Grand Rapids. where I bought it.
They probably sell them all at 100,000 miles before expensive things start happening.
Just put in the missing center console parts last night.