I have an `89 951 that unfortunately due to circumstances hasn't been
driven regularly over the past two years. While trying to get the car
registered again and we've come to a roadblock with the emissions check.
It has been failing the Nitric Oxide (NO) and Hydrocarbons (HC) checks.
Here are the test results below:

@ 15mph/1500rpm:
NO: 2092/791 (PPM measured/max)
HC: 200/116 (PPM measured/max)

@ 25mph/2500rpm:
HC: 730/755 (PPM measured/max)
NO: 42/91 (PPM measured/max)

Just wondering if anybody might be able to share any ideas about what
might be the issue. The car is equipped with a Speedforce Racing Turbo
and Lindsey Boost Enhancer...otherwise stock. We've never had any other
problems with emissions until now. Other than this, car seems to run fine and drive smooth. Any ideas where to start looking before I take it into the shop?

Thanks!
Chris

 

If you get them to test you in 1st for the 15mph test and 2nd for the 25mph test, you'll almost definitely pass.

My other thought is that you might have a low RPM misfire, since that can cause high HC and NO.

I don't think I've ever seen a good emissions result at 15mph/1500rpm on these cars. I've seen cars pass, but usually not by much.

 

I got my 86 944turbo pass the CA smog check, and my HC CO, and NO # was very very bad, the only way that I can get it pass is to install a new cat that I bought from www.summitracing.com , 2.5'' MagnaFlow Universal Catalytic Converters part #mpe 53006, only $55, go to a muffler shop and they will install it for about $30~60. then you will pass the smog....

 

My frineds car had the same issues. We did everything on the car. Plugs, Plug wires, 02 sensor, cap, rotor, oil change, high octane gas etc. We retested 2 times and still failed. Finally replaced the cat. Drove it around for 50 miles to heat up the cat. Retested and easily passed.