Only failed the NO, no engine light and she seems to run OK.

Here are pictures of my test results

FIRST TEST


SECOND TEST AFTER HIGHER RPM DRIVING




The scans are not very good, the NO reads 874 @ 15MPH on the first test and 903 @ 15MPH on the second, max is 424


A little info, V6 5spd 1997 144k miles, CAT replaced 2 years ago and passed then no problem.

 

Check your EGR valve as it controls NO emissions.

 

The low HC and low CO indicates it may be on the lean side. "Lean" causes NOx to increase.

 

Thanks for the info.

I'm going to look at my EGR valve and lines and also fill up with mid-grade octane this weekend.

 

Anyone think this could be due to low quality gas?

I made an EGR thread:
http://web.camaross.com/forums/showt...71#post4206871

 

NOx is formed from high combustion chamber temperatures, and high O2 concentrations in the A/F mix (lean). Could be running lean, coolant temp could be too high, possibly the use of oxygenated fuel. Using low octane fuel may cause detonation, which may increase combustion chamber temps, but only if the knock retard system was not responding correctly.

 

I'm thinking it may be the EGR valve or the gas I was using.

The Mobil 1 station I get my gas from causes my dad's Ford to ping and it seems to make my motorcycle vibrate more at higher RPM. (SEEMS).

The plugs seem OK... The fuel system should be OK since I've been using Lucas every fill up for last 6 months.

 

my 94 failed cause the ****er driving wouldn't shift into 3rd... I filed a complaint with management but they don't care.

 

I'm confident that my smog tech is competent.

 

Is there a more technical-based forum for Chevrolet vehicles?

 

I just passed and the tech did both the 15 and 25 MPH tests in first.