TRNW-2: MISCELLANEOUS, 2018 Silverado 5.3 with a misfire

[Fred Whitaker]

  If you do get anywhere around the oil pump,I would not cut any corners there. I have heard stories of  guys chasing random misfires at idle (when pressure is lowest) because of  oil pressure towards bottom of specs.
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From: trnw2-bounces at trnw.net <trnw2-bounces at trnw.net> on behalf of Jim Bockus via trnw2 <trnw2 at trnw.net>
Sent: Sunday, June 8, 2025 9:40 AM
To: Tod Chretien <tod at trnw.net>; Technical Discussion Forum <trnw2 at trnw.net>
Subject: Re: TRNW-2: MISCELLANEOUS, 2018 Silverado 5.3 with a misfire

Pretty common for the AFM lifters to fail and ruining the camshaft. If you have to tear down the top end it's best to convert it to traditional camshaft and lifters and disable AFM. Not sure if you can do this legally in California but it's common in Alabama. You do have to remove the heads to access the lifters.

I watched a video the other day about what a PITA it is to remove the oil pump which runs off the front of the crankshaft, the problem is accessing the oil pump pickup bolt, you're supposed to remove the oil pan to get to it but this guy modified a wrench to get to it. Then the next problem is reinstalling the bolt, I guess there's actually 2 bolt holes in the pump but it only uses one, he ground off the spot weld on the flange so he could rotate it and used the bolt hole in the pump that is accessible. I'm sure you can find plenty of information on YouTube.

On Jun 7, 2025 8:52 PM, Tod Chretien via trnw2 <trnw2 at trnw.net> wrote:

Post ID: 21395<https://www.trnw.net/trnw/forum_thread.php?post_id=21395&forum=2>
Date: Sat Jun 7 18:52:40 PDT 2025
Subject: MISCELLANEOUS, 2018 Silverado 5.3 with a misfire
This isn’t a transmission problem so please forgive me for that. I just bought a 2018 Silverado with 110K. It started making a light tapping noise on moderate to heavy acceleration. About 3 days later I had to punch it to beat some oncoming traffic and it started misfiring severely. The #1 cylinder is counting misfires so I pulled the spark plug and they definitely haven’t been replaced yet. Hoping for the best I replaced the spark plug but it’s still counting up on #1. I swapped the coil with #3 but it didn’t change. I hear the lifters on these AFM engines have issues. Does anyone know what goes wrong with the lifters and how to diagnose it? Would it have no compression? Sorry for the dumb question but book time is over 20 hours and I don’t want to do the wrong thing. Any help or insight would be greatly appreciated.

Tod Chretien
Ralph's Transmission
Modesto, California USA
tod at trnw.net



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