Hey board,
My 1990 240 failed ca smog test. High nox. Here are the readings; (NON TURBO)

15MPH
Hc meas(ppm) 13 allowed(max) 116 PASS
CO " " .01 " " .74 PASS
nox " " 2002 " " 791 (GROSS POLLUTER,OVER 1992)!

25mph

Hc " " 7 " " 91 PASS
CO " " .01 " " .62 PASS
NOX " " 1267 " " 730 FAILED

Ive got one free retest.

I have found that the vacuum solenoid for the egr valve is not working.
Will the restoration of the egr system be enough, alone, to reduce the nox down to acceptable levels? Is a properly functioning egr that effective in controlling nox formation?

OR should I be looking for vacuum leak, fuel pressure etc.
Timing is good(12degrees)
hot air is shut off from breather
engine temp, according to guage, is right on.
ego recently changed. and fuel filter.
I have been running 87oct fuel. I probably need to change that, at least for the test.

what else? Or should I rely on the egr restoration,

I guess you'll know Im trying to avoid the cat issue. I hope the cat is not the problem$$$.

tHANKS

Lawrence