99 Tahoe 5.7 vortex P0300 code HELP

[Mackb23]

Just replaced my 5.7 vortex with a brand new crate engine, everything went good but now it’s throwing the infamous p0300 code and just wondering if anyone else ever had this issue or knows what I can do to fix it thank you

 

[Fless]

It's running lean based on your short-term fuel trims (fuel is being added -- a lot!). One possibility is a vacuum leak, or something else could be causing that. Check the intake from the MAF to the throttle body to be sure there aren't any leaks in that plumbing. It could be a hose left unplugged, or damaged.

 

[Mackb23]

It's running lean based on your short-term fuel trims (fuel is being added -- a lot!). One possibility is a vacuum leak, or something else could be causing that. Check the intake from the MAF to the throttle body to be sure there aren't any leaks in that plumbing. It could be a hose left unplugged, or damaged.

I’ll definitely take a look at that in the morning! I appreciate it.

 

[Hoesgottaeat2]

Did the new motor come with new ignition components?
My '99 Hoe had a P0300 and it wound up being a bad distributor cap, that was replaced just months before the issue arose.
The new cap resolved the issue immediately.

 

[Mackb23]

Did the new motor come with new ignition components?
My '99 Hoe had a P0300 and it wound up being a bad distributor cap, that was replaced just months before the issue arose.
The new cap resolved the issue immediately.

It did not come with anything but I did replace the distributor cap and rotor, along with new plug wires and plugs
I’m also having multiple misfires on 1 and 5

 

[exp500]

It did not come with anything but I did replace the distributor cap and rotor, along with new plug wires and plugs
I’m also having multiple misfires on 1 and 5

Multiple parts on this series of trucks-most aftermarket parts don't work or not very long.
The first on my list- Dist cap/rotor. Use only Delco, Delphi, or United DCR820x only. Packard Wires a help also.

 

[exp500]

It did not come with anything but I did replace the distributor cap and rotor, along with new plug wires and plugs
I’m also having multiple misfires on 1 and 5

Gmt 400 trucks do not like certain aftermarket parts.
First on my list is Dist cap/Rotor- Use only Delco/Delphi, or United DCR820x. Packard wires a help too.
Looking at fuel trims- 1st do an idle leak check using carb cleaner around intake. 2nd- fuel pressure check, Best is a 6 foot fuel hose and stick Gauge under wiper. Report findings here. We're here to help.

 

[Mackb23]

What is this called, and could it have been a problem, I heard air coming out of it and when I took it off it just kinda crumbled in my hand

 

[Fless]

Looks like a vacuum line, but I wouldn't mind seeing a pic of where it is on the engine.

 

[Mackb23]

It the pcv valve hose, but I’m not sure if it could be part of the problem