Failed CA Emissions Test

[treetop_73]

Passed all the visual and functional checks but failed at 25mph at the Test Only

15mph
HC(PPM) max 122 -- tested at 114 Passed
CO(%) max 1.37 -- tested at .84 Passed
NO(PPM) max 1591 -- tested at 1578 Passed

25 mph
HC(PPM) max 77 -- tested at 121 Failed
CO(%) max 1.59 -- tested at 1.69 Failed
NO(PPM) max 1537 -- tested at 1116 Passed

So, whats needed?

Thanks.

[Malo83]

What type of maint did you do to the engine prior to the test ?

[Trick76]

I'm pretty sure H/C is due to the Catalytic. how old is it and the O2 sensor?? did you get it good and hot before taking it to the smog place??

[Alias137]

I disagree. I remember having to replace my catalytic converter on a 95 Tahoe we had when it failed the nox test. As for the failed hydrocarbon, I would replace cap, rotor, plugs, wires, and your air filter. Do not replace your air filter with a Fram filter though. The fram air filters have a tighter filtration, allowing a slightly lower ammount of air through- thus slightly increasing your hydrocarbons (runs slightly richer). I had the same problem last year. Also, you may want to replace your pcv valve. D before you go to get it tested.Drive it pretty good before you go to do your test- be sure it is running good and hot. Good luck!

[treetop_73]

No maint prior to test. Got a gas cap for the other tank that I never used as the PO didn't have a cap on it. I bought this thing 3 months ago and haven't driven it much or thought too much about it but found out from the wifey that the registration is due on Tuesday so I went to test it pretty much to see what it would fail on as I have never had a vehicle pass on the first try.

I drove it for about 30 min prior to the test and the temp gauge never got passed the first line. Even after the test on the drive home it never got passed it, just kind of hung around the first line. First I noticed that.

And it doesn't have a CAT on it. True dual with no cat but the tech entered it as single exhaust.

I will get a complete tune up; cap, rotor, plugs, wires, and air filter. It is a Fram though from the PO so I guess that will be changed to something else.

[Alias137]

When I tested my 86 last year, I went in without doing anything either. After I failed the pre test (I never want to fail a test since you don't get too many chances before you are a gross polluter) I went home and tuned her up. I wish I would have takedn a picture of my rotor. Destroyed beyond belief. I was amazed that the pickup even ran when I pulled the cap. So I replaced it all, went down and easily passed. I wouldn't worry about no cat though, your truck gvw is too much to require one for that year/weight combo. Be sure too that all of your vacuum lines are right. Having one off or in the wrong olace will (or can rather) cause your truck to miss and run on 7 cylinders only. This will fail you for sure, as you're putting all unburnt fuel right out of the tail. You'll know if your missing though- it will idle and run horribly.

[scottsdaleowner75]

My 86 scottsdale does have an o2 sensor, Neither should yours. The cats will make a huge difference. Also make sure its getting up to temp. That might mean a thermostat change.

[73chevyman]

a tune up will fix your problem and try those E3 spark plugs

[Malo83]

A tune up is a must(cap,rotor,plugs and wires if necessary) also change the oil and put in new filters (air/oil) and the deal with FRAM is BS i run nothing but FRAM air filters and haven't failed yet, and run the sheeet out of it on the highway before taking it in

[osaltyone]

Had the same problem failed @ 25. Kinda odd, but mine was the vacuum lines were all crossed. I had to tear all them out and route them according to the diagram.

http://67-72chevytrucks.com/vboard/s...d.php?t=367593

[68 TT]

Originally Posted by Alias137

When I tested my 86 last year, I went in without doing anything either. After I failed the pre test (I never want to fail a test since you don't get too many chances before you are a gross polluter) I went home and tuned her up. I wish I would have takedn a picture of my rotor. Destroyed beyond belief. I was amazed that the pickup even ran when I pulled the cap. So I replaced it all, went down and easily passed. I wouldn't worry about no cat though, your truck gvw is too much to require one for that year/weight combo. Be sure too that all of your vacuum lines are right. Having one off or in the wrong olace will (or can rather) cause your truck to miss and run on 7 cylinders only. This will fail you for sure, as you're putting all unburnt fuel right out of the tail. You'll know if your missing though- it will idle and run horribly.

A tune up is always a good place to start. I had a terrible looking cap & rotor on mine and it seemed to run fine. I bet the emissions were way off though.

http://67-72chevytrucks.com/vboard/s...51&postcount=2

[treetop_73]

I wanted to try the E3 plugs. I knew the cat was no issue due to the GVW from a previous thread I started when I noticed it was missing.

I will get it all done and post my results after I test again in a couple weeks. Thanks for the help.

osaltyone, where is the diagram? That thread links to itself.

[tucsonjwt]

My 83 454 passed emissions in Tucson every year for the past 8 years but almost did not pass this year. I took it through emissions on a humid, rainy day and did not change the air filter/pvc element, and oil/filter before taking it to emissions. Also, I make sure that the carb is leaned out as much as possible and still idles. I did the total tune up when I bought it, but did not touch it for the past 8 years - except for a new set of plugs. Replacing the cap, rotor, plugs and plug wires is always a good idea on an old vehicle, and cheap repairs. Get only Belden brand wires - NAPA has them under their brand name or buy them online. Good Luck