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If a failure of one of the DOD lifters - you'll hear it.

My 2013 Z71 developed a missfire on one of the DOD cyls at 65,000 miles and turned out to be a cracked plug. What happens is the cyls pumps a little oil when they get deactivated... coating the plug with oil then when the air and spark get turned back on, it overheats the plug cracking the insulator around the electrode.

BTW your gonna love changing the rear passenger side plug.

Will
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Beyond the typical suggestion of plugs and wires, I might want to spray around the intake at idle and see if there is a vaccum leak before you start tearing stuff apart.

Might want to check the coil harness also for breaks/splits/visible metal, theh can get brittle and sometimes folks are too rough with the wire and the connectors.

A cracked plug in my experience can cause problems, but I think they also made a ticking noise?

Can unplug MAF and it should run in speed density.

I think the fact the guy had the motor in and out makes me want to check over all the wiring.
 

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Discussion Starter · #23 ·
If a failure of one of the DOD lifters - you'll hear it.

My 2013 Z71 developed a missfire on one of the DOD cyls at 65,000 miles and turned out to be a cracked plug. What happens is the cyls pumps a little oil when they get deactivated... coating the plug with oil then when the air and spark get turned back on, it overheats the plug cracking the insulator around the electrode.

BTW your gonna love changing the rear passenger side plug.

Will View attachment 289271
This reminds me of what happened to my other work truck, 2010 F-150 4.6 two valve. Had it a few yrs and it had always run fine, then it started loosing power under load and shifting late and erratic and the mileage dropped from 15 to 12 mpg.

It acted just like a bad cat but the problem would occasionally clear up and run fine. No check engine light and the MAP readings looked normal, two different mechanics said to bite the bullet and throw cats at it but I am waay to cheap/smart to do this without all the symptoms matching.

About two months ago I was about a mile from the house and it blew out a plug......disconnected the coil wire connector and drove it home....still no check engine light LOL. Ran a tap through the hole and got a new plug in it and the truck now runs perfect again and the mileage is back to 15.4 average.
 

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Discussion Starter · #24 ·
PS John,

Just had a chance to look at the engine with the sun out and the poor guy who owned the truck got fucked by the "mechanic" who "rebuilt" the engine.....no sign of the heads being off the block or any other major repairs.

I have seen so many cases of this with guys from other countries, they take a car/truck to someone from their own country so they don't get fucked and wind up getting gang raped by their own people.
 
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