This is topic FAILED SMOG in forum Tech Talk at Northern California Ford Owners .
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Posted by 87_ssp (Member # 11152) on
:
I took my 90 fox to get sniffed today and it failed . I did a tune up changed
Spark plugs, wires, oil ,oil filter , cap n rotor. I didn’t not change the o2s and the catted h pipe is the original. Numbers I failed are
15mph
HC max 85 meas 87
25mph max 67 meas 72
15mph
NO(ppm) max 613 meas 669
25mph max 664 meas 452
I failed those three smog guy said to get new cats. Any ideas ? No codes come up and no CEL .
Posted by Martinna (Member # 12493) on
:
What is your timing at? Always set it to 7 degrees for smog. Lower timing lowers HC and NO. How long did you drive the car for before testing it? The O2 % numbers can indicate how your cats are performing.
Posted by 87_ssp (Member # 11152) on
:
My timing was at 10 , I did not know I can go lower . And O2 numbers were at 5.4.
Posted by Martinna (Member # 12493) on
:
Plus or minus 3 degrees timing from 10 is allowed. Lower timing lowers NOx and HC. You always want lower NOx and HC for smog. Pouring a bottle of G2P in your tank with 7 degrees timing and testing your car after a long drive on a warmer day will probably get you to barely pass. Your cats are tired. Post up what happens.
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