1987 Suburban R10 emissions problem due to modified intake

[thatgermanguy]

I got this sweet Suburban last year and needed to register it in Colorado. It failed emissions on HC and CO. When I bought it I noticed some tubes that seemed like something had been removed and the owner in Idaho (where they don't have the same emissions test requirements) said it was an air filter "some crap for California emissions you don't need" that he had removed. So... what did he remove? Could it be a reason for the poor emissions test results? Are there any tips people can give me on how to get the car to burn more cleanly? Plugs? Filters? Tune up? Additives? She starts and runs well but it smells like she doesn't burn all the petrol... Love this car and really want it to pass. Thanks! Here are some pictures that might help...

I saw this schematic that seems relevant but little explanation. It seems that the removed parts were the Air Cleaner unit... here is a link. Does that seem right in explaining the poor emissions performance?
https://www.gmpartsnow.com/oem-part...5PTE5ODcmdD1zaWx2ZXJhZG8mZT01LTBsLXY4LWdhcw==

 

[dd1990]

Sounds like your missing the stock air filter housing and preheat tube. This would not affect emissions out the pipe but it would not pass the visual in California, don't know about CO. In terms of emissions, a tune up will help, BUT do you still have stock intake manifold, tbi, with egr and all vacuum hoses attached? Do you still have a catalytic converter that would be the biggest problem if missing.

 

[Ricko1966]

Without pics we are guessing about a lot here. Please post pics of the engine so we can see the mods and try to help you.

 

[fast 99]

Is an under hood visual part of the emissions inspection? If all the vehicle needs is being lower than the limits an air pump and cat do wonders on emissions. Here they only did under hood if the vehicle needed a waiver. If everything installed by OEM is required some of it may be difficult to locate.