Rough Idle- want to bounce a few ideas off of everybody on what i have going on

[Sam71671]

i have a 2018 1500 with the 5.3. it has developed a rough idle up to around 700 or so RPM. it has a little over 78k on it, with nothing done to it until recently. i’ve changed plugs, wires, cleaned the throttle body, new air filter, and seafoamed the intake with top engine cleaner. also ran a tank full of seafoam motor treatment in the gas. it runs like a scalded cat once you hit the pedal, just idles like crap till about 700-800 RPM. also idles like crap at a stop light. it did have a random P0300 misfire code when i scanned it. my thoughts now are either dirty MAF sensor, fuel pump going out, or injectors going out. anybody else have any ideas? just wanting to bounce this off some of you guys.

 

oh and i have not checked any grounds yet either, but that was going to be a next step when i have time

[newdude]

Any metallic squeaking or ticking or knocking?

 

Any other codes besides the P0300?

[BigBadSierra]

https://www.crcindustries.com/gdi/

 

You have to keep these direct injection engines clear. 

 

I Used this on three trucks with a 5.3 DI engine regularly usually at the oil change and never had an idle issue.

[Sam71671]

no squeaking/ticking/ knocking that i can hear. soon as it hits 800 RPM all bobbling is gone and she’s ready to run

 

and yeah i have another can of seafoam top engine cleaner i thought about running thru it. I’m more of a yellow iron fella, i didnt do my research on these GDI engines until recently. i plan on installing a catch can soon too

[steelerdude15]

I'd start by cleaning your MAF and see if that helps before doing anything else.

Edited March 22, 2023 by steelerdude15