i spoke with an x smog tech a couple days ago and he said i failed only because it was running rich at low the test level 763 rpm but fine at the high 2418 rpm
READINGS in brief
The offending reading was HC at 142 and it shoulld have been 120>
that was all. Too much fuel or too little air(oxygen)

Anyone knowledgable enough on these readings to suggest a fix?
Possibilities through techs I spoke with and googling
#1 Replace plugs and wires as it was running rough ,like a small miss before the test( unburned fuel)
#2.PASSED O2 sensor replace ( passed)
#3 idle air control valve (not listed on inspection report, at least not as it is here)
#3 oil change,clean throttle body
#4 PASSED?.(NO VISUAL LEAKS) fuel pressure regulator,leak ? (no visual leaks)
#5 PASSED ...Pump Air injection (passed)
#6 PASSED catalytic converter but its $300+,so I may want to do that last if if other replacement dont pass me
(its already got 120K on it so.it'll be time in another couple years anyhow
#7 evaporative systems with a whole list...forget it
#8 PASSED vacuum lines sensor/switches
all 17 listed emission control systems passed,visual and function
OK enough the more I google and dig the more sub items that are still likely causes of increased HC. Well
beyond my interest level or ability to tackle. Ill just try and do a couple easy for me to do swaps and leave the rest to the smog man. Imregrouping for the launch in a day or two..depends on what I hear in the meantime .

 

You have 3 threads going on this....you only need one.

Is this your '90 E150?

Your idle HC is 142 against a 120 max, right?

And you have a slight miss at idle?

Check for vacuum leaks. Check for plug and wire and related issues.

If you can get to a smooth idle, you will probably pass.

You passed NOX and CO? If so, your cat is fine. Do not replace a cat that produces passing CO numbers. That's what it's there for, not HC or NOX.

Back to your list:

Plugs and wires: Replace if questionable or something obvious.

O2 sensor: Not in play. (No CEL, right?) Do not replace.

Idle air control valve: Clean it.

Oil change, clean throttle body: Yes, yes.

Fuel pressure regulator: Doubt that is in play. You would be rich at high speed too methinks.

Air pump and Mass Air Flow sensor are different. Do you have an air pump? If you do, it must be working or you would have failed on it as well. MAF can be cleaned and checked, google it for thousands of videos etc, some model specific so put your entire model info in and you may find an exact hit.

Cat, see above, leave the cat alone if you passed CO.

Evap: Did you fail on evap? No? Leave it alone.

I see your last comment is you give up. Good luck with that.

 

ha! yeah your right,Im still at it! hrs later!

Thanks alot for the tips.....

Oh,I guess Ishould have left this back in the van section then?
i thought since I was switching to a more specific smog discussion i should move it to a more appropriate smog (exaust)section.

 

Is there an oil additive that helps smog test failures here in Ca?
What specific out of range numbers would additives help ?

This question applies for my 90 E250 5.8L where the HC failed at 145 when the max allowable was 120.

 

Clean oil is all you need and the only oil related mod you can make to improve HC.

Did you fix your slight miss at idle?

 

yes,it had a bad plug wire. All others incl plugs looked ok.
BTW,the mechanic got to the number 1 and 2 plug through the opening behind the shock tower frame. he made it look so easy,but i know better. Putting the plug in was even more of a task as you can imagine.
the $140 Labor to R&R my own wires and plugs ($50)was well spent.
I have a feww more things to do before taking it back in for a retest.