Cyrus951

I failed Smog a couple days ago, what causes these numbers:

15mph:
RPM: 2597
%CO2: 14.1
%O2: 0.5
HC(PPM): 98 (Max 116)
CO%: 0.84 (Max 0.74) <--FAIL
NO (PPM): 2701 (Max 791) <--FAIL

25mph:
RPM: 2438
%CO2: 14.1
%O2: 0.5
HC(PPM): 103 (Max 91) <--FAIL
CO%: 0.80 (Max 0.62) <--FAIL
NO (PPM): 2769 (Max 730) <--FAIL

So I failed CO, and NO @ 15mph,
And HC, CO, AND, NO (All three ) @ 25mph

Why is my NO soooo high??
I bought a brand new cat last year.

Porsche-O-Phile

I thought you were running a test pipe (?)

Test and if necessary, change the O2 sensor; I'd start with that.

Cyrus951

I'm leading towards the O2 sensor as well, is it really testable with a multimeter? I thought the O2 sensor gives out a 0-1V signal..

DelMar951

My money would be on the cat, even though it's fairly new. I just went through hell with my Jeep GC that was a GP with numbers similar to yours. There was a leak in the exhaust manifold that I was told was the problem, replaced it, new plugs, wires cap, rotor and O2 senor as well, still came in a GP. Finally, I took it to the dealer and they quickly said it was the cat. It was an aftermarket unit that was just two years old with just 20k miles. Had it changed and all is well, nearly $1,000 later! Good luck.

Red1

You have a vacuum leak. Quite possibly more than one. This is getting common as the rubber dries out. Andrew Spence had a hell of a time getting his to pass, as I did last year. Your NOx is too high for a cat to clean up, no matter how new it is.

Do a search on emissions, there's a lot of stuff to filter through. Start looking at everything connected to your vacuum system. Hoses, DV, fuel breather valve, etc. Anything with a diaphram in it is a potential leak. I bought a vacuum tester at Sears, and everything I just listed was leaking on my car. My initial test results were similar to yours. It'll clean up, but it's likely to take some time to get it right.

deep_purple

Did they put a fan in front of the hood? the PO told me that the car I now have passed smog only after they put a fan in fron tof the car.

I may be way off, of course...

Danno

15mph:
RPM: 2597
%CO2: 14.1
%O2: 0.5
HC(PPM): 98 (Max 116)
CO%: 0.84 (Max 0.74) <--FAIL
NO (PPM): 2701 (Max 791) <--FAIL

The first fail at low-speed could be due to high combustion-temps, which cause high NOx production. This high-temp is usually caused by lean mixturs, but your HC is fairly high just under the limit here, so it's definitely not lean. The high CO confirms this as well (not enough oxygen to make CO2).

25mph:
RPM: 2438
%CO2: 14.1
%O2: 0.5
HC(PPM): 103 (Max 91) <--FAIL
CO%: 0.80 (Max 0.62) <--FAIL
NO (PPM): 2769 (Max 730) <--FAIL"

This last part shows that your cat is definitely out. That's because there's typically a criss-cross inverse function between HC and and NOx. Typically the higher the HC, the lower the NOx and conversely, the lower the HC, the higher the NOx. The fact that they are both over the limit shows your cat is not working properly.

Cyrus951

Dan,

I'm glad it's the cat.

KrazyK

I would get this sorted out before the next smog check.

lart951

that was 10 years ago, lol