Mechanics

SMOG FAIL ON NO

1991 Isuzu Trooper • 90,467 miles

Would not pass smog I ended up replacing headgasket, valve job, valve lashcomplete tune up, all new vacuum lines and pcv, sensors ect. It still failed just barely, it failed NO
max is 704 @ 15 mph it measured 854
max is 606 @ 25 mph it measured 638
tech checked egr working fine
tech suggested changing timing from 13 degrees to 9 degrees
Any Ideas?
Avatar
Mkelee@cox.net
February 21, 2012.




Check the EGR valve, a problem with it will caused the Nox -oxides of nitrogen to go high due to excessive combustion temperature

Tiny
Rasmataz
Feb 21, 2012.
The tech checked it out using a vacuum pump/gauge said it was working

Tiny
Mkelee@cox.net
Feb 21, 2012.
Tell him check the catalytic converter, oxygen and coolant temperature sensors-
AD

Tiny
Rasmataz
Feb 21, 2012.

AD