Cylinder Misfire Normal?

[John89]

So, I hooked up my 2023 1500 and JScan is showing on live data random cylinder misfires but no check engine light.

The count usually slows down once the engine warms up and increases very very slowly whil driving. Has anyone experienced this and is this normal? I’m assuming no code is thrown by the pcm because it hasn’t hit a certain threshold.

 

[CaliRebel]

Interesting... Im curious to what kind of responses you get.
Im no mechanic by any means but what grade fuel are you using? You might be getting detonation if you're using a lower grade.

 

[John89]

Interesting... Im curious to what kind of responses you get.
Im no mechanic by any means but what grade fuel are you using? You might be getting detonation if you're using a lower grade.

I always use 89 or better. If I fuel up at Costco I always use 93.

 

[6of36]

There was another thread like this a few weeks ago. I don't remember the responses, but you could search.

 

[John89]

There was another thread like this a few weeks ago. I don't remember the responses, but you could search.

Thanks; Yeah, that was me who posted in general discussion but I didn’t get any responses where someone directly answered my question. So, decided to post in powertrains as I felt this section was more appropriate.

 

[CalvinC]

I'm surprised you haven't gotten more responses.

I'm not a HEMI expert, but generally multi-cylinder misfires in real time would be a problem. As opposed to perhaps a single cylinder where you might just have a faulty coil pack and/or spark plug. Or a few stumbles on cold start that stop after a few seconds.

However, if you were really having that many misfires across all cylinders, I would think it would present as a clear and noticeable problem, including odd vibrations from the engine like driving over a rumble strip, along with reduced performance and a check engine light. Yes not just any misfire throws a CEL, but something that consistent should.

So since you didn't mention any such symptoms, my inclination would be to fault JScan. Never used it, but it may be worth double checking the PIDs you have there - I've used plenty of other scanners and monitors and some of the generic PIDs don't actually do what you think, and/or require further modification to the calcs.

 

[John89]

I'm surprised you haven't gotten more responses.

I'm not a HEMI expert, but generally multi-cylinder misfires in real time would be a problem. As opposed to perhaps a single cylinder where you might just have a faulty coil pack and/or spark plug. Or a few stumbles on cold start that stop after a few seconds.

However, if you were really having that many misfires across all cylinders, I would think it would present as a clear and noticeable problem, including odd vibrations from the engine like driving over a rumble strip, along with reduced performance and a check engine light. Yes not just any misfire throws a CEL, but something that consistent should.

So since you didn't mention any such symptoms, my inclination would be to fault JScan. Never used it, but it may be worth double checking the PIDs you have there - I've used plenty of other scanners and monitors and some of the generic PIDs don't actually do what you think, and/or require further modification to the calcs.

Yeah. Is there another app that also has access to viewing the live data for individual cylinder misfire counts?

I’d really like to see if anyone else with the JScan OBD2 scanner app sees the same on their end.. I don’t see any indication of a noticeable misfire but since I had my engine replaced I just want to be certain it’s the app or “false positives” rather than a true issue.

 

[theblet]

You sure you’re not in demo mode? It shows misfires in there.

I’ll try to check for you tomorrow.

 

[John89]

You sure you’re not in demo mode? It shows misfires in there.

I’ll try to check for you tomorrow.

Lol… I wish I really was in demo mode!

Thanks man, really appreciate it!

 

[theblet]

Lol… I wish I really was in demo mode!

Thanks man, really appreciate it!

No worries !

 

[Scap]

Not sure how it determines a misfire event, but those numbers don't seem bad to me.

But I was used to watching knock count when I was running tunes in the past.

 

[theblet]

This is all I see for knock (demo mode not my truck) any usefully date here?

 

[theblet]

Here you go. This is data from cold start, with a 20 minute drive. One half throttle acceleration, and one full throttle acceleration. Everything else is normal driving on back roads between 45 and 60 mph. 73 degree outside temp w/ 93% humidity. Running 87 octane from Murphy, so I expect timing to be retarded to compensate.

It kicked 1 error on cylinder 1 when I cold started. I expected this since the engine will be in closed loop until at operating temp.

The others kinda of popped up randomly.
Engine runs fine tho. How is yours running? I’m thinking with a higher octane top tier fuel I may not see this.

 

[Scap]

This is all I see for knock (demo mode not my truck) any usefully date here?

View attachment 167216

Knock retard will tell you how much timing the ECU is pulling due to Knock. I don't see anything that would give a Knock Count on that list. *my experience is with Ford's, so some of that may not carry over.

 

[John89]

Here you go. This is data from cold start, with a 20 minute drive. One half throttle acceleration, and one full throttle acceleration. Everything else is normal driving on back roads between 45 and 60 mph. 73 degree outside temp w/ 93% humidity. Running 87 octane from Murphy, so I expect timing to be retarded to compensate.

It kicked 1 error on cylinder 1 when I cold started. I expected this since the engine will be in closed loop until at operating temp.

The others kinda of popped up randomly.
Engine runs fine tho. How is yours running? I’m thinking with a higher octane top tier fuel I may not see this.


View attachment 167223

Thanks man. I feel much better now.. Those counts under the same or similar conditions mirror mine. I always run 93 though since I have a Costco near by. Engine runs fine, no indications of a misfire at all.

Here are my counts this morning for reference:


Yesterday my counts looked like the below, but as mentioned previously, when I see the counts go up I don’t feel, hear, or see anything that indicates a misfire. And when I’m driving the counts either stop increasing or I’ll get 1-2 misfires on a random cylinder before I have none:

 

[theblet]

Thanks man. I feel much better now.. Those counts under the same or similar conditions mirror mine. I always run 93 though since I have a Costco near by. Engine runs fine, no indications of a misfire at all.

Here are my counts this morning for reference:
View attachment 167233

Yesterday my counts looked like the below, but as mentioned previously, when I see the counts go up I don’t feel, hear, or see anything that indicates a misfire. And when I’m driving the counts either stop increasing or I’ll get 1-2 misfires on a random cylinder before I have none:

View attachment 167234

I gotcha. If it runs fine and doesnt get horrible fuel mileage, i wouldn't worry about it.

 

[Orion10182011]

Must be a threshold before the ECU pops the code. Mine threw the code for Cylinder 4 at about 1500 miles. Dealer replaced coil and plugs for that cylinder and all has be quiet since. Nearly 40k miles now.

 

[John89]

I gotcha. If it runs fine and doesnt get horrible fuel mileage, i wouldn't worry about it.

I guess about as good as can be. I have 285/65r20 Falken wildpeaks which are heavy as heck and a 3.5” lift

 

[John89]

Must be a threshold before the ECU pops the code. Mine threw the code for Cylinder 4 at about 1500 miles. Dealer replaced coil and plugs for that cylinder and all has be quiet since. Nearly 40k miles now.

Yeah, there is a threshold before a trouble code is thrown. This is what actually prompted me to start monitoring the misfires. My cylinder 7 caused the check engine light to come on, took it to the dealer and they did the same as yours.

 

[theblet]

I guess about as good as can be. I have 285/65r20 Falken wildpeaks which are heavy as heck and a 3.5” lift

View attachment 167245

Looks about right. I am averaging 17.5 right now. That with alot of idling and city driving. If i only drove highway at 60mph id get 22-24.