Getting an old Audi to pass emissions inspection

My trusty 89 Audi 100 failed the Texas annual emissions inspection, with
excessive HC at idle ( 373 vs. the 220 limit ). All other parameters were
under the limit, including HC at speed. The inspection station said to get
an additive from O'Reilly Auto Parts called "Guaranteed To Pass", and run it
through a tank full of premium gas with Techron. Then run the car for about
15 miles to get it good and warm before inspecting it again.

I have 15 days to get the car re-inspected without having to pay another $40
fee.

What do you think of their advice? Do you have any other suggestions?

FYI, the car has been maintained by the book by a very competent Audi
mechanic, and it is current on oil changes and tune-ups; all the basics are
correct. I also add Techron at every oil change. He says it may need a new
catalytic converter. The odometer stopped working several years ago, but I
estimate the mileage at around 300K miles. I only put about 4000 miles a
year on the car now, so it is driven mostly in town two or three times a
week for short trips.

Thanks for your opinions!


--
Stephen Clark
89 Audi 100
Houston, Texas USA

Stephen Clark wrote:
> My trusty 89 Audi 100 failed the Texas annual emissions inspection, with
> excessive HC at idle ( 373 vs. the 220 limit ). All other parameters were
> under the limit, including HC at speed. The inspection station said to get
> an additive from O'Reilly Auto Parts called "Guaranteed To Pass", and run it
> through a tank full of premium gas with Techron. Then run the car for about
> 15 miles to get it good and warm before inspecting it again.
>
> I have 15 days to get the car re-inspected without having to pay another $40
> fee.
>
> What do you think of their advice? Do you have any other suggestions?
>
> FYI, the car has been maintained by the book by a very competent Audi
> mechanic, and it is current on oil changes and tune-ups; all the basics are
> correct. I also add Techron at every oil change. He says it may need a new
> catalytic converter. The odometer stopped working several years ago, but I
> estimate the mileage at around 300K miles. I only put about 4000 miles a
> year on the car now, so it is driven mostly in town two or three times a
> week for short trips.
>
> Thanks for your opinions!
>
>
>
The four T44s that I used to have never had a problem with inspections.

Try to replace you air filter.

Your mechanic probably is familiar with the ISV Idle stabilization valve
and the throttle body switch that activates its controller. You might
want to have its function checked.

If yours has an O2 sensor, that might need replacing.

There is also an adjustment for injector frequency (I don't remember
what it is called) that can adjust rich / lean conditions. Your mechanic
could look at adjusting that with a dwell meter.

The first thing I would do is to try the suggestion of the inspectors
with the "Guaranteed To Pass" and the Techron. It might just be dirty
injectors.

Let us know how it tests.