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

[Tod Chretien]

Thank you for the replies. After I posted, I found this bulletin.

#19-NA-219: Diagnostic Tip on Misfire, Chirp, Squeak, Squeal or Tick 
Noise, Malfunction Indicator Lamp (MIL) Illuminated - DTC P0300, P0301, 
P0302, P0303, P0304, P0305, P0306, P0307 and/or P0308.

After reading this TSB I am thinking it may be a flat cam because the 
tick noise had a little chirp to it. The TSB says that it's very 
difficult to see if the cam lobe is worn through the lifter hole. Often 
times the worn cam is missed.

If I remove the valve cover and watch the lift on the rocker arms, how 
do I distinguish between a worn cam lobe or a collapsed lifter?

I am going to do the relative compression test possibly today or maybe 
tomorrow.

-- 
Best Regards,
Tod Chretien
TRNW Inc.
http://www.trnw.net

On 6/7/2025 9:28 PM, Steve Everett wrote:
>    I believe I'd pull the valvecover for that side and watch the 
> rocker, if it is moving some but not full movement the spring on the 
> lifter is likely collapsed,  That is one of the cylinders that the DOD 
> affects,   since it happened after you punched it chances are its just 
> the lifter as opposed to the camshaft lobe being damaged.
>
>    Steve
>
> On Sat, Jun 7, 2025 at 9:53 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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-- 
Best Regards,
Tod Chretien
TRNW Inc.
http://www.trnw.net
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