I getting really frustrated with my pickup right now. I have to continuously take my truck into the dealership with check engine lights. The first 2 times they replaced the spark plugs. The third time they replaced a spark plug wire. The forth time they replaced another spark plug. The fifth time, they replaced two spark plugs and the valve cover on the drivers side. Now for the sixth time, they think putting in new pistons will fix the issue. Between the 5th and 6th time we are talking about 3 days.

Last Thursday was the fifth time I was there and after I left the dealership, it was running great. Then on Sunday, I went to the store and when I left, I started up my truck and it started miss firing again. The dealership told me this morning that it was a random miss fire code.

On the 5th time it happened, I drove the interstate for a good 45 miles and the miss fire cleared up on the way.

On my way home from the dealership today, ran it pretty hard hitting 4k RPM between shifting, by the time I got home, it stopped miss firing.

I am sitting here wondering if anyone else has had this issue. I am also wondering if the new pistons will fix the issue or if it is something else like a coil pack or something.

What evidence do they have to believe the issue is mechanical?

Also, what did they do to rule out outside factors, such as ingesting coolant or oil?

Admittedly, I have never heard of anything like this, and hope that tearing an engine apart like this is happening on GM'* dime.

They think the plugs are getting fouled out from the AFM. Right now they are thinking the piston rings are fouled out from the plugs continuously getting fouled out.

They changed the valve cover because they said in these years the oil port was very small and it tends to seep down into piston 7 causing the fouling.

Luckily yes, it is still under warranty so it does not cost me anything. At the same time though it is extremely frustrating to have to keep taking it in.

I guess there are many TSB'* for 2011 on down for this issue but nothing on 2012.

All of the Chevy/Gmc forums I have visited recommend tuning the AFM out immediately after purchasing trucks and reinstalling when warranty visits are necessary. Problems usually appear around the 30- 40,000 mile mark. They speak of a oil catch can for the LS engine as well and definitely for the DGI ecotex engines. I am holding onto my 1997 Silverado because of the horror stories with AFM failures. Typically not all 5.3L trucks are affected, but trust issues will not let me pull the trigger.

How do I go about tuning out the AFM? Do you have any reference sites for this?

Visit www.silverado/sierra.com, Daiblo tune and Range are a couple of tunes for AFM. Not cheap but if it will save your engine it'* well worth it.