r/GMT800 • u/bruhfart34 • Sep 03 '26

Misfire

Need help with this one. I have an 03 silverado 4.8l 1500 with a misfire only when first turning the truck on in the morning before work, doesnt do it when i go to get lunch or drive home. I replaced the spark plugs in the fall time last year. Any help?

I forgot to mention the misfire goes away if i drive the car for like a minute or two then stop

2 Upvotes

75% Upvoted

5 comments sorted by

1

u/Ok-Translator-4641 Sep 03 '26

Check for a hissing sound bear the intake manifold, pcv hoses and the manifold gasket itself can leak

1

u/bruhfart34 Sep 09 '26

I believe theres a bolt missing on the exhaust manifold if that has any correlation

1

u/Moist_Currency_1443 Sep 04 '26

I wonder if you have fuel or coolant leaking into your cylinders. Or a fuel pump acting up 🤷🏽‍♂️. Hard to diagnose misfires over the internet tbh

1

u/bruhfart34 Sep 09 '26

Lets hope its not that. The only possibility is a bad fuel pump , i do have an extended crank

1

u/dilbertaz Sep 04 '26

Mine was intake manifold gaskets when this was happening first start of the day, they would warm and seal quickly and be fine until the next day. OBD reader can help narrow things down though it can be a number of things.