High HC and especially CO #'s

[Sleeper]

This is not Buick related, but I'm looking to help a friend out.
She has a Volkswagen Vanagon that went in for a E test and passed the idle but failed the higher rpm test. (Passed last year and isn't driven much.) Did a oil change and tune up before the test as well as adding a bottle of methanol to about 1/4 tank of gas.
HC was 171 114 limit
CO was 2.38 .81 limit

Bad O2 sensor???
(BTW no cat)
Just curious... There was a small bung on the exhaust pipe just before the resonator that was leaking. Is this for some sort of probe with the cap missing, or is it a air bleed?

Any help is appreciated.

Thanks,
Paul

 

[gofstbuick]

If it is suppose to have a cat and it's missing, then there is part of the reason for high emissions. The O2 helps the cat work more efficiently (narrow band types). So if the O2 is not switching fast enough, high emissions will also result. That pipe is used to probe emission before the cat so a comparison can be made with readings at the tailpipe (to test the efficiency of the cat).

 

[Sleeper]

This is an early 80's model no cat.

Paul

 

[gofstbuick]

Since there is no cat, don't put one on (even though it would pass if you did; fire hazard). But to address the issue, the engine is most likely running rich. if you cure the rich problem, then the HC will fall along with the CO until the mixture is too lean, then HC will rise, but CO will fall or flatline.

 

[Sleeper]

Thanks
Paul