Morning misfire?

[Rubyram2023]

Hey yall!

For the past 2-3 weeks on first startup my 2023 etorque hemi with 18k on the ODO sounds like it has a misfire, or wants to die down. I only noticed it on first morning startup, even after work it doesn’t seem to do it. I do not have a CEL or anything but this again it’s only started this about 2-3 weeks ago..

I’ve ran a complete new full tank of gas through it and there was no change.

I have a video recording, currently trying to post it..

 

[Rubyram2023]

 

[dts828]

Do you feel the misfire? If it had misfire I would suspect you would have code. Perhaps exhaust leak(broken bolts or warped exhaust manifold) that you don't hear it as much once engine is warmed up.

 

[Rubyram2023]

Do you feel the misfire? If it had misfire I would suspect you would have code. Perhaps exhaust leak(broken bolts or warped exhaust manifold) that you don't hear it as much once engine is warmed up.

Yes I also feel it and can see it on the tach

 

[Richard320]

There are a couple possible culprits.

One is a bad fuel injector. If it leaks, after it sits for several hours, you get a fuel puddle in one cylinder's intake. When you start, it fouls the plug intermittently and you get a misfire until it all clears. If the injector has been dripping a while, you'll get carbon buildup on the tip that soaks up some of the gas until it gets saturated. It also can give a bad spray pattern so you'll get a lean misfire

You can try pouring a bottle of Techron or Seafoam injector cleaner in the tank at the next fillup. It won't hurt anything if it doesn't halp.

Second is a dirty throttle body. Where it wants to sit is between two steps of the throttle motor, so it is constantly trying to adjust, but if the throttle plate is goopy, it will stick and require an extra push to open it, then it's too fast, so it drops it but it drops too low because it's dirty. Repeat endlessly.

Pop the intake duct off (key off, engine off) and wipe out the throttle body and the edges of the throttle plate with a rag soaked with carb cleaner. Or paint thinner, if you have it but not carb spray. Something that will dissolve oil and evaporate away or can burn off without causing damage. Don't spray carb spray directly in there --- if it pushes past the seal and into the throttle motor you'll really have problems.

 

[Av1]

You can try pouring a bottle of Techron or Seafoam injector cleaner in the tank at the next fillup. It won't hurt anything if it doesn't halp.

The same thing was happening on my first start-up of the day, and this took care of it.

I used Lucas, but Techron or Seafoam would yield similar results.