Just wanted to get some opinions from you guys, and yes I have read every single post referring to this issue in the search function. I have had both heads rebuilt 20k miles ago and engine serviced as well and a new catalytic converter was installed at the same time.

I failed three weeks ago in the 15mph NOX but passed in the 25 mph NOX. This was all I failed.

I was told to try cleaning the EGR and/or replace the Catalytic Converter. I look the cheaper route and ordered the gaskets and removed and cleaned the EGR and EGR intake tube myself. After some stuck/sheared bolt problems the EGR was put back on and I ran some fuel system clear through the gas tank. The tank was almost empty when it was tested the second time.

Retest results:
15 mph
NOX
from 1200 to 2400 ppm
Max 900

25 mph
NOX from 700 to 2900 ppm
Max 900

And all the other measurements went up slightly but not enough to worry about.

Other considerations at this time is replacing the Oxygen sensor as I have pinging at low rpms and have been told I am running lean. Also, the muffler shop has told me my EGT's are hot and I am slowly cooking off coolant, but the engine temps are low.

Thought?
<img src="/forums/images/graemlins/patriot.gif" alt="" />

How old is your cat? <img src="/forums/images/graemlins/rodent.gif" alt="" />

It was installed 20k miles ago and about 20 months ago

I recall hearing the replacement cats are not designed to last very long and in some cases need to be replaced prior to the next test. <img src="/forums/images/graemlins/confused.gif" alt="" />

I hope I heard that wrong as I'll probably be in the same boat come Nov.

Hope someone else has better insights for you. <img src="/forums/images/graemlins/kewl.gif" alt="" />

New cat or secret sauce is my thought.

Can you post the other emmisions numbers? I'm curious to see how lean they look. A bad o2 sensor could do it so could an intake vacuum leak.

A couple of basic tests might help. Do you have a vacuum gauge to get the idle vacuum with?

Kevin

I can post the numbers tonight or tomorrow as I'm at work right now and don't have it readily available.

I don't have a vacuum gauge, but I could purchase one pretty easily.

Use a Vacuum guage to check the the Vac at idle and buy the kit with the vac pump so you can check the EGR valve function per the FSM. Esure the EGR ports in the intake are clear of carbon deposits.

If thats all good to go, You might try running a "Sea Foam" treatment to clean carbon deposits from the combustion chambers. Deposits can raise temperatures in the CC causing high NOX levels.

Changing the O2 sensor is a good idea as well especially if you dont know when it was last replaced.

I went through this with my 89 when the NOX was off the charts and was flagged as a gross polluter. I changed the 02 sensor and retested and cut the numbers in half but still failed. Once I got the EGR system squared away and ran a sea foam treatment it passed easily. HTH

Thanks. I've been looking into the Seafoam from the posts of other members and think it is a good way to go. How long after the seafoam treatment should I wait to smog again?