kilikopela

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

Red1

You have a vacuum leak. That's what's throwing the NOx so high. BTDT

genikz

That is probably true, but keep in mind high HC #'s usually mean there is unburnt fuel (ie running rich). High NOx #'s are a sign that your combustion chamber temps are high. How hot was the engine when you have the test done?

Have you done the usual stuff? plugs, new air filter, oil change?


Chris

kilikopela

Thanks for the help guys! The car always had a tendency to run rich in the past, I recall a lot of buildup of carbon on the tail end from unburnt fuel...but it never seemed to affect the smog checks before. Before taking it in to the smog station, I would take the car for at least an hour of spirited driving so it was already quite warm. We've already done the basic tune up/maintenance stuff... Besides vacuum issues, what about the health of the cat? We're using a "newer" cat we picked up on eBay...I just want to get the small things outta the way before dropping big $$$ into a new cat!

genikz

I was told my cat was dead, by the folks I bought my car from. They even labeled it a "gross polluter" based on their prelim tests. After a call to the Calif. Air Resouce Board or whatever they are called, a technician there said a cat can "come back to life" after it has been "killed" by running poorly/rich, if the car is returned to a "healthy" running condition.

I had a vacuum leak (high NOx, low HC's) which I fixed and I passed the re-test with numbers well within limits.

Please see this thread from a friend of mine at work regarding smog readings:
http://www.honda-tech.com/zerothread?id=701236