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Random misfire

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Old Dec 26, 2019 | 12:32 PM
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Default Random misfire

2005 ram 5.7, 144,000 miles, all stock

About a week ago I started up my truck (cold start) and got a loud tick tick. I confirmed it was at idle and increased with light tap of throttle. Lasted for about 10 seconds and went away.


Today I started up my truck (cold start) and got the loud tick again. Same as above, light tap of throttle confirmed tick increased with rpm. After about 10 seconds it went away.

Between the two above occurrences I used my truck plenty with no issues.

Again today I stopped at a store for about 15 minutes, came out to start my truck (completely warmed up engine) and it did the tick again for about 10 seconds. The engine light came on this time. Got home and checked the code, p0306, cylinder 6 misfire.

No matter if it’s ticking or not it idles smooth and drives fine.

I pulled cylinder 6 plugs, replaced them and swapped the coil with cylinder 2 coil, reset the codes and I started twice with no ticking.

Being random and it goes away after 10 seconds could this still be an internal issue? If this is an internal issue can more damage be done by continuing to drive it, could be a week or two before a mechanic can look at it.


 
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Old Dec 26, 2019 | 04:32 PM
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What oil are you using?

Probably a lifter issue. These engines are rather notorious for that.
 
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Old Dec 26, 2019 | 04:34 PM
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Valvoline high mileage
 
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Old Dec 26, 2019 | 04:35 PM
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What weight?
 
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Old Dec 26, 2019 | 04:36 PM
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5w - 20
 
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Old Dec 26, 2019 | 04:40 PM
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Well, that's the right stuff at least. (these engines are rather sensitive about their oil......) Problem becomes, if it IS a lifter problem, only way to know for sure is to pull the intake and have a look. And since your problem is intermittent, you may not see anything out of place. You could be proactive, and simply replace the lifters, but, that is not an inexpensive proposition.
 
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Old Dec 26, 2019 | 04:43 PM
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Can a “bad” lifter trigger a misfire code? If i have s bad lifter does that mean the cam is probably trashed?
 
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Old Dec 26, 2019 | 04:46 PM
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Yep, if the valve doesn't open enough, the cylinder won't get a good mixture, and it may fire, but weakly. PCM will see that as a misfire.

Cam may not be trashed yet, but, eventually, the lifter will destroy it. Assuming it IS a lifter problem...... Hemi tick is a lot of fun to diagnose...... Given your symptoms though, it does point in that direction.
 
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Old Dec 26, 2019 | 05:58 PM
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Originally Posted by mopar4u
2005 ram 5.7, 144,000 miles, all stock

About a week ago I started up my truck (cold start) and got a loud tick tick. I confirmed it was at idle and increased with light tap of throttle. Lasted for about 10 seconds and went away.


Today I started up my truck (cold start) and got the loud tick again. Same as above, light tap of throttle confirmed tick increased with rpm. After about 10 seconds it went away.

Between the two above occurrences I used my truck plenty with no issues.

Again today I stopped at a store for about 15 minutes, came out to start my truck (completely warmed up engine) and it did the tick again for about 10 seconds. The engine light came on this time. Got home and checked the code, p0306, cylinder 6 misfire.

No matter if it’s ticking or not it idles smooth and drives fine.

I pulled cylinder 6 plugs, replaced them and swapped the coil with cylinder 2 coil, reset the codes and I started twice with no ticking.

Being random and it goes away after 10 seconds could this still be an internal issue? If this is an internal issue can more damage be done by continuing to drive it, could be a week or two before a mechanic can look at it.
If its still running ok after the swap it may be good , but if its high mileage i would change all plugs, wires an coils , even a bad fuel injector can set a misfire code
 
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