1994 Toyota Pickup fail smog

Tiny
WMEJIA
  • MEMBER
  • 1994 TOYOTA PICKUP
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 268,000 MILES
My pick up failed smog for high nox. Egr is working fine. Cat was replaced two years ago. Compression is around 150 to 155. I am thinking maybe timing chain is to loose. Burns no oil or no oil leaks. At 25 mph it passed but not at 15 mph. I dont know what else to check.
Monday, October 4th, 2010 AT 2:21 PM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
The EGR valve is normally responsible for high Nox if its not opening and will raise the combustion temperature over 2500 F deg, also the catalytic converter and a control system that stays in the open loop mode
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Monday, October 4th, 2010 AT 3:47 PM

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