random misfire code but not missing

[bowlofturtle]

I've seen this happen on a few cars now i'm being to wonder what the actual problem/fix is.

These are coilpack cars. They have P0300,301,302 and etc. Pretty much every cylinder misfire stored but its not currently happening. Most of the time the car has 100-150k. Due for spark plugs.

What normally does this mean? Its normally found on hondas. The car drives perfectly fine. Quick look overall and nothing is broken or out of place. I glance at the VC gasket or Intake manifold. Anything that can link all 4 or 6 of cylinders. I know the coilpacks were not the problem.

I generally recommend them do a "tune-up" and start from there, which i mean spark plugs and air filter. I never get a chance to see if the problem happens again.

I'm curious if this is a sign that cats are going bad or something. Thoughts?

 

[Boomer]

I think some misfires are so subtle the driver does not notice them. Years ago I had a Chevy pickup that did this. Always felt perfectly smooth but there were the misfire codes . Replacing the plugs solved the problem. I think the plug may actually be firing and igniting the fuel but the computer is reading the weak spark somehow...resistance, voltage required, etc.

 

[BAJA_05]

Normally found on Hondas??? Yeah ok -- let me guess -- your one of these Hyundai/Kia fans all of a sudden right???

 

[Chris142]

Originally Posted by Boomer
I think some misfires are so subtle the driver does not notice them. Years ago I had a Chevy pickup that did this. Always felt perfectly smooth but there were the misfire codes . Replacing the plugs solved the problem. I think the plug may actually be firing and igniting the fuel but the computer is reading the weak spark somehow...resistance, voltage required, etc.

X2. You may not feel them but it knows.

 

[Trav]

A scan tool using mode 6 data will provide actual misfire count readings. Low misfire counts may not be that noticeable but over 2% will throw a code Dirty injectors can also cause misfires..

 

[Imp4]

Originally Posted by BAJA_05
Normally found on Hondas??? Yeah ok -- let me guess -- your one of these Hyundai/Kia fans all of a sudden right???

I disagree.
I think the question and the manner in which the OP stated it comes across as very reasonable.

 

[wemay]

Originally Posted by Imp4
Originally Posted by BAJA_05
Normally found on Hondas??? Yeah ok -- let me guess -- your one of these Hyundai/Kia fans all of a sudden right???

I disagree.
I think the question and the manner in which the OP stated it comes across as very reasonable.


Me too. Weird response for sure.

 

[Junk]

We've run into Hondas that had a bad coil on one cylinder that due to the way they are wired would set misfire codes for all 6 cylinders. Pretty sure there was a TSB somewhere for it but I cant remember what it was exactly for off of the top of my head.

 

[bowlofturtle]

Originally Posted by BAJA_05
Normally found on Hondas??? Yeah ok -- let me guess -- your one of these Hyundai/Kia fans all of a sudden right???


Not sure whats going on.... but i'm not a fanboy of any brand nor am i bashing another

Ive just seen this issue 3 times on V6 hondas and not on other cars.

Granted i'm a DIY-er not a tech. People come and ask me general questions. And go on their way. Hence why i never know what the solution is, but this last one was on a MDX that i might have to work on.

I might update this with mode 6 over the weekend. But i drove it around and it did not miss a beat. All i had with my was a Autel basic scanner

 

[clinebarger]

To recreate misfires.....You need to run the crap out of the vehicle! High Load-Low RPM stresses the coil/plug the most.

Ignition systems are fascinating as they work on a "On Demand" basis....As seen with KV waveforms. You can probably watch some videos on it to get an idea.

 

[Trav]

This^
On forced induction engines an iffy ignition or fuel system can be catastrophic and its not healthy for the cat(s) in any case. Lots of turbo/supercharged engines have met their end due to going el cheapo on parts and poor maintenance. OE parts and no extended anything in the maintenance dept especially OCI will keep them living a long time.