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Misfire cyl 7 but not collapsed lifter-Bad gas?


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Posted (edited)

Truck is 2014 1500 6.2 with 55,000miles had afm turned off with tuner since 6000miles

 

So did a full throttle acceleration and had a CEL misfire cyl 7 and traction control light on couple weeks ago and lost power and truck was chugging.  Next day swapped coil packs with another and cleared code.  It ran fine for a couple days than CEL for cyl 7 and tract control light again when accelerated hard.  I was at half tank so filled up with BP 93 and added octane booster and changed plugs/wires and drove fine for 4 days and even with hard full throttle acceleration no issues.  Then after 4 days accelerated hard and CEL came on but only flashing but it didn't drive any different and no loss of power.  CEL flashed for about 20-30 sec and went off.  It was Cyl 7 misfire again.  I brought it in to shop 5 days later and he tested Fuel injectors with scan tool and drove it reading data for misfires and fuel pressure.  He floored it a bunch of times and had no CEL and injectors were all ok.  He said he has had failed lifters before with Cyl 7 but he said mine is not driving or sounding like any of the ones he has seen.

 

He said there is a bulletin for upper fuel system cleaning with cyl misfires but the dealer would have to do it as he didn't have the machine.  He thinks it is bad gas or a gummed up intake valve and it is coaked up with carbon.  All of my issues started a day or 2 after I put in Sams club 87 octane for the first time.  I have always ran 93 from top tier then about 3 months ago started getting sams 93 gas and then for first time filled up with Sams 87.  

 

Would a bad tank of gas cause these issues I am having.  Anymore suggestions?  

 

 

Edited by Payton34
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1 hour ago, Payton34 said:

He said he has had failed lifters before with Cyl 7 but he said mine is not driving or sounding like any of the ones he has seen

Lol get a new mechanic. You can literally pull the valve covers off and see if a rocker arm has stopped moving. Just because it doesn't drive or sound like any of the ones he has seen doesn't mean it doesn't have it

 

I am unsure though, seems super duper weird

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If I pull off my valve cover to check rockers do I need a new gasket to put cover back on and anyone no torque spec on valve cover?

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2 minutes ago, Payton34 said:

If I pull off my valve cover to check rockers do I need a new gasket to put cover back on and anyone no torque spec on valve cover?

 

 

You "should" put a new gasket.  If its not deformed/flatten too bad, you can probably get away with pulling it off and putting it back on just to see what's going on.

 

89 in.lbs is the torque spec.  

 

If you pull the cover, check for tightness/contact of the rocker arms to the push rods.  If its loose there, you've probably got a bad lifter or a bent pushrod.  

 

If nothing is bad, could be an injector or the 87 octane you probably shouldn't have put in the tank.  

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