Posted by MikeK on April 10, 01 at 10:05:00:
I need help with this one.
I appreciate evryones previous advise - after four months I finally passed my smog test - but just barely.
In 10/00 my truck failed The NO portion of the test - badly. the results were 2630(15mph)/2523(25mph) measured vs 975/835 allowed. CO2,02,HC and CO were well within limits.
I compression check showed an average of 160 psig across all 8 cylinders. None were out of range.
I replaced the following:
spark plugs, wires, cap and rotor, 02 sensor and catalytic converter ( this was purchased through Summit for my 3" exhaust.). I replaced my 180F t'stat with a 210F. I also changed my oil and ran that Cheveron cleaner through my system twice (two cans per tankfull each time).
Making these changes brought the NO numbers down to 1517/1299. At least now I wasn't a gross polluter which helped my conscience. I did not expect this, but the CO2,HC and CO values went up, the 02 went down - but they were all well within range.
Next I replaced the EGR valve. This got my numbers to 962/647 measured with 975/835 allowed - finally I passed but just barely. With these numbers I'm sure I won't pass next year.
Does anyone have any ideas as to why my NO is so high?
Can it be my computer? I read DSB's post on integrator/block learn - could my truck be running rich because of this?
I would appreciate any help. By the way, the muffler guy said my cat would only last about one year.
Thnak you,
MikeK