Bad AC Delco Spark Plugs?

[ForestryGuy]

Hi all,

 

Im experiencing some issues with misfiring following plug replacement done by my local dealership. My truck is a 2018 Sierra 1500 with the 5.3L. 101,000 miles, never gave me a problem until I had the plugs changed. I had the plugs changed as PM, no issues before replacement. 
 

Picked the truck up tonight after they went over it again following the initial misfire issue, started driving home and misfire. No CEL but you can feel it. Back to the dealership. We hooked it up to the computer and noticed the #1 cylinder is misfiring consistently. We pull the plug and see cracked porcelain and carbon. Replaced that plug. Hooked it back up and put things looked good. Driving home I feel like there is another random misfire, I feel it while driving but no CEL.
 

The service manager mentioned they had a few bad plugs recently. I thought I’d fire off a post here and see if anyone else has experienced problems recently. Dealership is taking care of me so far so not a problem but I’m perplexed why OEM plugs are giving me a fit. We didn’t do the wires with the replacement - mechanic felt they were in good shape and didn’t need to be replaced. 
 

Thanks!

[newdude]

8 minutes ago, ForestryGuy said:

Hi all,

 

Im experiencing some issues with misfiring following plug replacement done by my local dealership. My truck is a 2018 Sierra 1500 with the 5.3L. 101,000 miles, never gave me a problem until I had the plugs changed. I had the plugs changed as PM, no issues before replacement. 
 

Picked the truck up tonight after they went over it again following the initial misfire issue, started driving home and misfire. No CEL but you can feel it. Back to the dealership. We hooked it up to the computer and noticed the #1 cylinder is misfiring consistently. We pull the plug and see cracked porcelain and carbon. Replaced that plug. Hooked it back up and put things looked good. Driving home I feel like there is another random misfire, I feel it while driving but no CEL.
 

The service manager mentioned they had a few bad plugs recently. I thought I’d fire off a post here and see if anyone else has experienced problems recently. Dealership is taking care of me so far so not a problem but I’m perplexed why OEM plugs are giving me a fit. We didn’t do the wires with the replacement - mechanic felt they were in good shape and didn’t need to be replaced. 
 

Thanks!

 

 

Which plug did they use?  12622441 which was the original plug GM used in the 14-18?  Or 19459511 the current service plug for those?

 

I think we had one or two bad 19459511s, but the 12622441 we've never had issues with it.  

[ForestryGuy]

Looks like they used 19459511. Can they still get the 12622441 plugs?

[ForestryGuy]

Issue is resolved, I think. Turned out a plug wire gave up the ghost after our diagnostic test last night. My initial service request was plugs and wires. Service tech said wires were still good. I contend 2/3 of the issues would have been avoided if the wires were replaced with the plugs. 
 

Kudos to Town & Country GM in Alamosa CO. The service manager Frank and the advisor Joaquin are great guys who helped me out with diagnosing this issue. 
 

I’ll probably change out the wires to a new set of OEM if it happens again.