99 Tahoe 5.7 vortex P0300 code HELP

[Eman85]

Might not be the total problem but it sure needs replacing. That's a pure vacum leak.

 

[Mackb23]

So, a quick update, replaced the pcv valve along with the hose connections, and it’s not bogging down when I take it out of park, still throwing the code and running a little rough, gonna dig some more into it this weekend, would any one suggest getting new grommets for the intake?

 

[Fless]

Might be helpful to post new short- and long-term fuel trims after your initial repair.

 

[Mackb23]

Might be helpful to post new short- and long-term fuel trims after your initial repair.

Unfortunately I don’t have the OBD scanner anymore so now I’m at a loss

 

[exp500]

Unfortunately I don’t have the OBD scanner anymore so now I’m at a loss

Amazon.com

 

[Mackb23]

Amazon.com

Will be here Monday, thank you!!

 

[east302]

would any one suggest getting new grommets for the intake?

They can seep oil over time, wouldn’t hurt to swap them if they’re original. They’re the same part for both valve covers.



As others mentioned, aftermarket distributor caps are a weak point.

Follow the hard vacuum line from the PCV fitting over to the solenoid on the passenger firewall. Make sure it isn’t broken somewhere. From the solenoid is another vacuum line to the heater valve.

 

[Mackb23]

They can seep oil over time, wouldn’t hurt to swap them if they’re original. They’re the same part for both valve covers.

View attachment 442250

As others mentioned, aftermarket distributor caps are a weak point.

Follow the hard vacuum line from the PCV fitting over to the solenoid on the passenger firewall. Make sure it isn’t broken somewhere. From the solenoid is another vacuum line to the heater valve.

Okay yeah they’re original. Came with the new motor, I’ll get some, I also just changed the MAP sensor, what’s the best way to check the hose from the solenoid to the heater core ?

 

[east302]

It’s just a rubber hose from the solenoid to the valve (#14 in diagram) so it can crack over time. The only way it could cause a vacuum leak is if the solenoid is energized - when the a/c temp dial is in the Max detent.

#20 is the hard line to the PCV fitting.

 

[Mackb23]

So this is what I’m currently looking at in park.