trouble code po401 po302 and po452 on my silverado 5.3L 1500, 1999

[Raymond86]

Hello, my name is Raymond and i have a problem i can't solve.

 

my car keeps giving me trouble codes (po302, po401 and po452).

 

i replaced the egr valve and tubes and tested the connector.

i replaced the coils and sparkplugs and cables.

i replaced the tank pressure sensor.

 

the car doesn't go through the emission test ;(

 

i hope  someone here can help me out.

[Jsdirt]

I would concentrate on the #2 misfire.

 

EVAP is an emission-only thing and shouldn't affect operation, unless a purge valve is stuck open and making the vehicle run either pig rich, or very lean.

 

Bad EGR components can cause a rough idle.

 

Did you have any of these symptoms? If not, you just fired the parts cannon - you'd have been better served burning your money for heat.

 

Does the vehicle actually have a misfire? What's compression on #2 if it does? What are your fuel trims at idle, cruise, and full-throttle? What were the symptoms regardless of the codes?