Constant misfire

[DRAMIT]

Hopefully you guys can help I’m at an end pass. I have a 2018 Dodge Journey 3.6 with 54,000 miles. I keep getting a cylinder 2 misfire multiple cylinder misfire and O2 lean bank 2. I’ve replaced the coils, plugs and fuel injectors. I also had to replace a leaking valve cover gasket and I still have the same problem. The light will go off for a couple days and come right back with the same codes. It idles rough with no load in the engine but that has gotten better since I replaced the injectors. I’ve checked for a vacuum leak and everything there is good to go. Not sure why I can’t find a problem! Any help you can give us appreciated. Thanks in advance!

[5rebel9]

Howdy! My not that common for such low age or mileage. What kind of use does this get most of the time? And just so member here can investigate code diagnostics better, what are the P format codes showing up?

[DRAMIT]

This is the second time the coils have been replaced in the 2.5 years I’ve owned it. I assumed it was cheap coils. Went with all molar parts this time. Also she has always run E85 in it. Not sure if that makes a difference but the injectors were gummed up pretty good. Codes are P2099 P0300 P0302. My scanner also shows the P0300 and P0302 as permanent codes?

Edited August 31, 2021 by DRAMIT
Code update

[5rebel9]

HMMM, The P2099 has me intrigued along with your posting of "gummed up" injectors. Quite possible there is excessive "gunk" build up on the intake valves as part of the problem along with fouling of the upstream O2 sensors.

you've done a LOT of work already, my suggestion if this is a true flex fuel is to run a couple tanks of reg. unleaded with Seafoam cleaner added to the fuel.

Otherwise you may be looking at an ECM problem ... from a fast code look up. 

DEFINITELY keep in touch as how things go.   

[DRAMIT]

I’ve been running regular gas for over a month now. Treated with Lucas 2 times. Fuel consumption is still up and the idle like I said is still a little shaky. All other aspects it runs fine. Is there a way to test the ECM to verify it’s the problem?

[5rebel9]

Only way I know of is with a high level scanner . Please give complete info when posting, I was under the impression that only E85 has been being used. IF your scanner has live data and you are good with interpreting the readings, check your fuel trims and O2 sensor readings.

There was a problem a while back on newer 3.6's with troubles from the crank sensor and if an AWD a real pain to change. Crank sensor will not always throw a code.

[John/Horace]

Another possibility is the intake manifold seals, on cylinder 2  either upper or lower could bad.
Not that expensive to change. Look closely for cracks or damage to the plastic manifolds when they are off.  Car accidents sometimes damage manifolds.

Extra air from bad seal or cracks can cause cylinder misfire issues.

 

When people change the plugs they often reuse these seals; can get you later.

Edited September 1, 2021 by John/Horace

[Evlmarine]

clean the throttle body with some seafoam and a soft bristle tooth brush.  Start it for about 15 mins then add seafoam spray through your throttle body ( 1 whole can) and 1/4 can through vaccum line at about 2000 rpms and don't panic if it stalls. let it sit for about 15 mins then drive it normal for a couple of blocks and if you can, hit the highway so you get it up to ateast 60 mph. Your check engine light will come on but it will clear after a couple of days. Cleaning your throttle body restores some of your power and engine response specially with new coils and plugs.