Re: [DML] Re: high hydrocarbon in exhaust

[Robert Brandys <BobB@xxxx>]

Rendy,

What state are you in? I have been involved with emission testing of 
cars since the 1970s. Overall your car emssions are quite low. I am 
suprised that the idle HC limit is lower than the High rpm HC limit. 
This is ususally not the case because the converter runs a little 
cooler at idle. 

I also find it a little unusual that these standards are so tight for a 
1981 vehicle. Again, with age, the standards usually become less 
restrictive. Higher mileage vehicles will have less restrictive test 
standards.

Lowering HC less at idle to below 120 ppm is tough. Since you have 
alreadly dealt with the likely ignition causes, this does not leave much 
other choice than replacing the converter. However, it is not typical 
for a converter to be worn out after so few miles.

Your low idle CO indicates the A/F ratio is good. Usually, a bad 
converter goes a much higher CO level.

How, often is your car driven. ? Your converter may just need a good 
2-3 ride on the highway to burn off a lot of low temperature 
contamination. 

I would try this first and then retest the car before changing the 
converter.

BOB

rendy_cheng wrote:

><This is from original question poster>
>After following the advise on this forum, I have replace the O2 
>sensor, spark plugs, spark plug wires, Dis cap, dis rotor.
>Earlier today, I had my car smog check again.. Guess what? It 
>failed the test again. Result from the test are following :
>
>HC (ppm) Max allow:150 My car: 111,
>CO (%) Max allow:1.50 My car: 0.54
>CO2 (%) Max allow:NA My car: 13.8
>O2 (%) Max allow:NA My car: 1.1
>RPM 2466
>
>So... for high RPM, it is okay. The following values are from idle 
>case.
>
>HC (ppm) Max allow:120 My car: 241 (too high)
>CO (%) Max allow:1.50 My car: 0.67
>CO2 (%) Max allow:NA My car: 13.4
>O2 (%) Max allow:NA My car: 1.5
>RPM 734
>
>Other than catalytic converter, what else can be the cause of 
>this..
>

>



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