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Old 04-27-2012, 11:31 PM
Registered User
Join Date: Jan 2008
Location: Redondo Beach, CA
Posts: 188
1993 190E 2.6 CA smog failure again.... Help!

I took the car in for a CA smog test today with high hopes of an easy pass, due to a new cat and o2 sensor in 10/2010. What a disappointment... I failed and my numbers were worse than my pre-cat O2 sensor replacement. I have put 5098 miles on this car in a year and a half... I am about ready to take it to the junkyard, but probably won't because it drives great.

Below are my test scores from today and from when the Cat and O2 sensor were done...

4/27/12 test//

15 mph test..


%CO 14.01
%O2 0.1%
HC ppm 86/146
CO% 0.50/0.21%
NO ppm 697/636

25 mph test//

CO% 14.5
O2% 0.0
HC(PPM) 51/73
CO% 0.48/0.18
NO ppm 724/295

My test results after I had the CAT and O2 sensor replaced 17 months and 5098 miles ago are here..

15 mph test..
%CO2 MEAS 14.4, %O2 0.0, HC Max 86 test 8, CO% 0.50 max/ 0.00 test, NO(ppm) max 697 test 5

25 mph test..
%CO2 MEAS 14.9 %O2 0.0 HC Max 51 test 12, CO% 0.48 max/0.01 test, NO(ppm)max 724/test 5.

I should have taken the "baby benz" for a freeway blast before the smog.. I know... where did I screw up ?

1993 190E 2.6 135k
1989 Ford Thunderbird SC 5 Spd 79K

Last edited by riorust; 04-29-2012 at 05:38 PM.
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Old 04-28-2012, 04:51 AM
davidlee's Avatar
Join Date: Mar 2012
Location: Portland OR
Posts: 606
You could try running a Qt. of Xylol / Xylene from home depot (or almost any other hardware store) paint dept. in about a 1/4 tank of fuel and giving it another go.
my buddy lives in San Diego and he has a 85 380sel that he has to do that to, to get it to pass. its a cheap trial.

Just a thought
Good luck

David Lee Portland OR
87 300D
87 190E 2.3
84 230E Euro
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Old 04-28-2012, 12:00 PM
Registered User
Join Date: May 2008
Location: San Mateo, CA
Posts: 102
I used a bottle of Good to Pass (GTP) bought from a local auto store and a tune-up. Before getting the smog check, I drove for twenty minutes on the freeway and when I was waiting in line for my turn, I left the engine running.
200 75 W115 (Mom's)
190e 90 2.6 W201
E320 95 Wagon W124
72 BMW 3.0 CSI
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Old 04-28-2012, 01:06 PM
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Join Date: Dec 2003
Location: Palm Springs, CA
Posts: 782
I take our cars to my indie. He does a pre-check and then takes it to the smog guys. Always passes and only charges $50 for his service.
Can't b eat that!
'93 320CE 205K
'95 E420 125K
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Old 04-29-2012, 04:09 PM
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Join Date: Mar 2008
Posts: 33

The car is running very rich. Make sure that the OVP relay has not failed and subsequently put the car in "limp-in mode." Usually the check engine and abs lights flicker on the dash when this happens.

Check the air filter of course and look for vacuum leaks as vacuum leaks on fuel-injected engines cause the system to go rich to compensate.
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Old 04-29-2012, 05:32 PM
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Join Date: Jan 2008
Location: Redondo Beach, CA
Posts: 188
I will have some time tomorrow. I plan on checking out all the vacuum lines, plugs, air filter (plugs and air filter only have 5k miles on them), testing the o2 sensor. I did notice a crack in the distributor cap... so I will pull that and check it and the rotor out. I also plan on testing the plug wires.. I seem to remember reading that the plug wires should show around 3k ohms.. not sure on the coil wire.

The car seems to be running very smooth and the mileage has not changed , that I can tell. This smog stuff really ticks me off every two years.

I almost forgot... I will also test the OVP..
1993 190E 2.6 135k
1989 Ford Thunderbird SC 5 Spd 79K
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Old 04-30-2012, 10:56 PM
Registered User
Join Date: Jan 2008
Location: Redondo Beach, CA
Posts: 188
Today I checked the air filter, the OVP and found a blown fuse, replaced it and noticed an immediate improvement in a cold start (one or two cranks vs 10-15), ordered a new cap and rotor as the cap had a crack on it and the rotor did not look too good. The plug wires tested around 3k ohms across the board, so I'm assuming they are okay. Found a couple suspect bits of vacuum line and replaced them.

I did not have a chance to pull the plugs, or test the O2 sensor.. was called into work.. the nerve. After I test the O2 sensor I will test the duty cycle and make any required adjustments. Is there anything I am overlooking? How critical is fresh oil, I am at around 1700 miles since my last change, albeit with mostly stop and go?

1993 190E 2.6 135k
1989 Ford Thunderbird SC 5 Spd 79K
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Old 05-01-2012, 02:24 AM
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Join Date: Mar 2001
Location: SF
Posts: 220
Idle Air Control?

Are the hoses OK? They caused me fits before I replaced them on another M103. Leaky Fuel Distributor Plunger O ring leaking into the manifold? Oil Change? It helps....

1987 190D 2.5 NA 1986 300E 5speed. ⬅️Stolen!
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