Misfire Cyl 4 while coasting

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DILLIGAF

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Well I got a weird one this week. Truck decided to throw a CEL, So I did some investigation and was able to reproduce the Misfire code.

If I get up to Speed dosent matter if it WOT or Slow upshifts. If I let the truck coast for a long time the Cyl 4 Misfire Code pops up.

Truck Runs perfect and everything is new since I did a cam swap.

Will do the basics this weekend, Swap the coil pack, Put in new plugs, Check my headers for leaks, do a compression test ect.

I just hope its not a bad Valve Guide, That would suck having to do that again.

Just looking to see if Anyone ever got a weird CEL like this and what was the cause of it ?
 

Fast69Mopar

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Well I got a weird one this week. Truck decided to throw a CEL, So I did some investigation and was able to reproduce the Misfire code.

If I get up to Speed dosent matter if it WOT or Slow upshifts. If I let the truck coast for a long time the Cyl 4 Misfire Code pops up.

Truck Runs perfect and everything is new since I did a cam swap.

Will do the basics this weekend, Swap the coil pack, Put in new plugs, Check my headers for leaks, do a compression test ect.

I just hope its not a bad Valve Guide, That would suck having to do that again.

Just looking to see if Anyone ever got a weird CEL like this and what was the cause of it ?
When I see this issue the first thing I look at with my laptop is the MDS Solenoids. You said you have a new cam and lifters but did you delete the MDS?

I'd the MDS is still intact I would monitor the MDS solenoid for cylinder 4 while attempting to duplicate the misfire. What state is the #4 MDS solenoid in when the misfire occurs?
 

Fast69Mopar

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MDS, never head of her ;) . Those parts are all in the trash :p
Haha good. So, with a deceleration misfire, obviously check the plug in the #4 hole, swap plugs, coils, etc. If you have long tube headers inspect the knock sensor on the right bank and make sure it is securely fastened to the block and the wires are properly secured.

With a scan tool monitor the STFT and LTFT while attempting to duplicate the misfire and make sure your fuel trim is not going crazy along with the right bank oxygen sensors.
 

Tach_tech

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That’s very odd to get a misfire code during coast/decel. The vast majority of time during coasting misfire monitors are disabled since you’ll be in decel fuel cut off. You can see this with a scan tool if you monitor injector pulse or the fuel trims. During decel fuel cut off both the short and long term fuel trims will freeze and not change.

Do you have any way to actually monitor misfires? The misfire might be happening as it transitions out of decel fuel cut off.
 

Lee Peterson

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I think Hp tuners has a misfire counter, it would be nice to see what the other cylinders are showing for misfires.
 
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DILLIGAF

DILLIGAF

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With a scan tool monitor the STFT and LTFT while attempting to duplicate the misfire and make sure your fuel trim is not going crazy along with the right bank oxygen sensors.

Do you have any way to actually monitor misfires?

Heading out now with my HP tuner will post my findings .
 

Fast69Mopar

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Yup! just added it to my VCM Channel list
Good idea. Put as much info as you can in tht scanner and take a log while attempting to duplicate the issue and post the log. I'll take a look at it.
 

RedSRT4Me

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With a scan tool monitor the STFT and LTFT while attempting to duplicate the misfire and make sure your fuel trim is not going crazy along with the right bank oxygen sensors.

The right bank O2's doesn't have anything to do with P219B codes would it?
 

Tach_tech

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In my experience P219B is usually not caused by a faulty O2 sensor. Pretty much anything that could cause an air/fuel ratio imbalance can set this dtc.
 

Fast69Mopar

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In my experience P219B is usually not caused by a faulty O2 sensor. Pretty much anything that could cause an air/fuel ratio imbalance can set this dtc.
You are correct that it is normally not caused by a faulty O2 sensor. That is exaclty why I said it can be associated with the right bank O2's but there are multiple things that can cause P219B. Almost every single time I have worked on a vehicle or P219B it was not the oxygen sensor that was at fault. I have only replaced the oxygen sensor a few times to correct that DTC. The poor data that I was referring to is being caused by something else.
 

Lee Peterson

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Were new intake manifold gaskets installed could be leaking or popped out of place during install. You can swap drivers side o2s to pass side and see if code changes to a P219A.
 

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