It needs to be very, very hot. A few minutes won't cut it.

Like I said, freeway 70mph in 3rd gear. Hold it at ~5500 rpm for a good 15mins or so. Its the only way to heat the cat up enough to fly by emissions. A few minutes won't do anything. A new engine may be enough with all the computer adjustments, but with our older engines -- they WANT you to fail.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Fair enough. Thanks for the insight.
Still curious as to whether holes in exhaust would have any bearing on emissions. Downdraft from the cat, but you never know.

15mins 5500rpm! can our cars handle that without overheating?

__________________
1992 300CE
BilsteinSport
Vogtland
Borla
EuroLampsAllAround
3pc18" Staggered BRABUS Monoblock IVs
http://i95.photobucket.com/albums/l1...MG00656Sig.jpg

FS/FT: 17" OEM 6-Spoke Wheels
FS/FT: 16" Lorinser RS-90s
FS: W211 Steering Wheel

Yes it can handle it it, no don't do that. It won't help you pass smog. Your engine is running rich. The most likely culprit is a failed or lazy O2 sensor. Relatively cheap and easy fix.

The emissions test looks at HC, NO, and CO as a % percent of the total emissions so the hole is irrelevant. If there is O2 leaking into the exhaust (possible between pulses) they will fail you. Thats why the last line in his emissions test is "CO+CO2% 13.1 6.0 min PASS 13.4 6.0 min PASS". This checks for exhaust dilution with outside air.

__________________
CENSORED due to not family friendly words

O.K. Next round. Passed on 25/25 HCs. 127 out of a possible 130, so barely. Now failed on NO ppm, 50/15 test. 1067 on a maximum of 990. Would this be the EGR? Why would it pass with flying colors on the last test (see above #s) and fail, just barely, on this test? I put in a new O2 sensor, so that helped.
Any ideas?

Here are the new numbers.
25/25 Test
Reading Allowed
127 130 HC ppm
.02 .83 CO%
792 905 NO ppm
13.0 6.0min CO+CO2%

50/15 Test
Reading Allowed
00073 00134 HC ppm
0.01 0.75 CO%
01067 00990 NO ppm
13.5 6.0 min CO+CO2%

Did you change the oil. I recommend changing the oil on all high mileage MB's the Day or THE MORNING before the test. The used oil blows by the rings and elevates the numbers. It worked for me. All my numbers were out of range early one cold morning in Texas. Car was therefore running a little rich. Changed the Oil and went back on a warmer day later in the after noon...brought 'er in HOT!....she passed with flying colors. You should have seen the techs face. He was literally like WTF! He asked what I had done and I told him.
1) 92-93 Octane (Always before the test... and add a can of that liquid Inspection Pass stuff (yeah I know its prolly just some "snake oil"
2) Fresh Oil change night before
3) Bring the car in HOT...Leave it running while you wait
Long as its not missing and you did a tune up in the last coupla years, I would worry too much about the rotors,wires or plugs.
Hope this helps and good luck!

__________________
Regards,

Albert
aldedmon@yahoo.com

Have not changed the oil. This would be a good time (and reason)to change it, though. Thanks for the advice.
I'm just wondering about how the NO ppm went from well within specs to way high (301 ppm to 1067 ppm).

I did bring in the car HOT! I drove around town about 45 before the test.
I'm glad the HC's went down, but why the hugely elevated NO?