Hey all. I could use some insight about emissions readings.

I ran my trusty '87 daily driver Carrera through the infamous California emissions test today. Even at 135,000 miles the car passed with flying colors, but I did notice a curious change/jump in the NO reading.

I've owned the car for many years. I have posted the last four tests ('98-'04) for your review here.

Note the box in yellow -- the high NO reading. Any idea what this high reading may indicate?

FYI: The plugs have 10,000 miles on them. The engine was fully warmed up. It had also been idling for ten+ minutes before the test. The fuel tank and oil tank were both full. The oil needs changing soon.

Any thoughts are appreciated. Thanks.
Bob Prosser

 

It appears that the CAT is getting "tired" which affects the NOx levels most
versus the CO and HC. Hopefully, you haven't installed a performance chip
which can also significantly affect the NOx levels.

Check out this web site (www.systemsc.com) on the Graphs page and the
Problems page for some useful info about emissions.

Have Fun
Loren
'88 3.2

 

Thanks Loren. That sounds like a reasonable explanation. Now you mention it, I did add a chip since the last test date. One of my advertising clients, Powerchip, offered me their product as part of my early research. (You may have seen my ads in Excellence, Car and Driver, etc.)

Turns out, the chip that I pulled-out was not stock either (I had purchased my car way back when with a few miles on it). In other words, I have no way to go back to stock. I have no complaints with the Powerchip -- in fact it cured some ills manifested by the other chip.

Does the added NO have an effect on the catalytic converter? After reviewing the web site you mention, I cannot tell if this is the case.

One other idiosyncrasy: if I am stuck in traffic, loping along for a long spell, then hit open road and run it up WFO in, say, third gear to redline, the engine will start to ping in the upper rev range and puke out some light brown smoke. But once that happened, it will not do it again. It has cleared its throat, so to speak. The car has always done this -- less with the newer chip. I chalk it up to crappy, low octane California donkey pee (use Chevron and an occasional bottle of Techron).

Any thoughts are appreciated.

 

The more NOx the harder the CAT has to work and the shorter its life.
As you probably know, most/all performance chips advance the timing
to make their claimed improvements which results in more NOx and
pinging. Porsche has a jumper on the the '88 & '89 3.2s (Pin 10)
for California & Japan cars to reduce the NOx. The Pin when grounded
retards the timing.

Have Fun
Loren
'88 3.2

 

As an FYI, I've been told from the email side of RennList that since my Carrera's CO is at 0%, it is running lean.

Anyone know if I can richen my 3.2 up a little by making small, 1/8 turn adjustments to that set screw on the on the throttle body?

Do I need to have the air flow meter adjusted?

Must I use a scope to make these adustments?

Thanks in advance.
Bob

 

First, you really need to check the CO before the CAT. The AFM can be adjusted
by loosening the spring inside to richen the mixture. Don't do this until you're
really sure that it's too lean. The CO will always be very low the O2 sensor connected.

Good Luck
Loren
'88 3.2