emissions gurus (1 Viewer)

[rightlane]

hc-1.81 standard-4.00 pass
co-28.33 standard-40.00 pass
nox-7.33 standard-5.50 fail

any knowledge would be greatly appreciated here. i've read some threads talking about an egr failure, engine running too hot, bad cat, and the heater control valve. my truck does overheat on the freeway, cools off within 2 miles after the off ramp. i've replaced the entire cooling system except for the water pump ( due to it not weeping ). i did advance the timing, i couldn't see any numbers so i adjusted the ball to the bottom of the window, it was 1/2 way between the needle and the bottom of the window. i'm wondering if the nox failure could be related to the advanced timing? it was normal temp when tested. and how do i check the heat control valve? i'm hoping for an adjustment fix and not a new egr fix. thank you

 

[mpetersrx7]

Read this... sounds like you want to back off on the timing.

http://www.nichols.nu/tip766.htm

 

[NocalFJ60]

From what I have learned if you have a high NOX most likely it is a EGR problem. Have you check out the EGR system with the FSM? You can pull a vacuum on the top of the EGR valve while idling and the motor should die. Then that means your EGR valve probably is working but not getting vacuum to open it?

Was this smog test done at idle?

 

[rightlane]

the test was done while at idle and higher rpm's. i'm minus an fsm, is it an easy explanation for the egr test?

 

[NocalFJ60]

This might help if you don't have a FSM.

http://www.autozone.com/servlet/UiB..._us/0900823d/80/18/91/36/0900823d80189136.jsp

Down the page there is a picture of 2F EGR hoses.Seems like if it is failing at idle it would be the CAT. I don't think the EGR valve open if any while ideling so the CAT is suppose to reduce the NOX. Anyone know if this is right?