Smog test Failed 91 300CE - Info

[MARINE_V]

Hi guys been a while since I been here, just wanted to know if any of you had a problem passing smog, I have a 1991 300CE that failed and was classified as Gross polluter. I Live in California. Have any of you had this issue. Just need to know where to start. The print out said just about every thing passed on the test but it fail at:

HC (PPM)
MEAS=908

CO (%)
MEAS=4.67

Result
GP Fail

Just looking at info as to where to start, thank you so much and any info will be appreciated.

[mespe]

Change the oil, make sure the car is good and hot (at temp) and try again. Lot's of times the HCs build up in the oil and are released.

[MARINE_V]

I did that before I even took the car to the smog shop.. I replaced oil filter and changed the oil. Sunday and Smogged it on Monday.

[mbdoc]

With the CO at the HIGH level...either the O2 sensor is inop OR the fuel mixture has been adjusted too rich & the O2 sensor CAN'T work.

[MARINE_V]

That brings me to another question I had. Are there two O2 on this car? Does anyone know. I went to a part store and I asked to price an O2 senor and they looked it up and they said there where two, a lower and upper O2, is this true?

[ohiomike]

I am pretty sure there is only one sensor and the parts catalogue says just one. I would bet you what you have is a bad O2 sensor but the light doesnt indicate it. That happened to me a few years ago. Spent a lot of money on parts but it turned out to be the O2 sensor. That engine eats them up.

[ps2cho]

There is only one O2 sensor on the M104. I wouldn't trust any local part stores.

[mbdoc]

Only 1 O2 sensor on that car & most cars thru 1995.

[Jim B.]

The smog test criteria in California vary by county.

The toughest are in the San Francisco bay area, and the so called LA smog basin, and the weakest, are in the cow counties.

Where do YOU live? Update your profile ( CP ) on here please.

You could take the car to a "test only" facility and I think for about $38, most of them will run your car, and see if it passes, and for the money you paid give you a second chance to try again after you tweak it a bit somewhere else.

If it passed the SECOND time, they will issue the smog certificate.

And NOT charge you for the re test, as you already paid your $38
under the 2 tests for the price of one, deal.
~~~~~

Unfortunately, once the smog test is performed, the tech, pushes a button and the results are INSTANTLY tramitted to Sacramento.

Incredibly, once a friend of mine who had a 1982 Mercedes 380SEC, had a car pass smog clean (these older Mercedes Benzes usually burn clean, they are notorious for that; my 1991 560 SEC has ALWAYS passed easily, to this very day from brand new,) but the Smog technician accidently pushed he WRONG button, and my friend's car was mis-labeled as a Gross Polluter even though it wasn't/

My friend was an attorney, and he was hopping mad; You would be, too, if this happened, but short of filing a lawsuit against the BAR and the state, he had no choice but to spend another $700 he told me, to get the mess sorted out...not too long after that he got rid of the car and has never owned another Mercedes Benz.

If it passed the SECOND time, they will issue the smog certificate.


I know someone who re registered his 1988 Mercedes in an "Address of convenience" after if failed, and he told me now he doesn't have to smog it at all. This is Lake County, one of the cow counties. The information from me is hearsay and I can't prove it though.

Even more desparate people could maybe register the car out of state with a residential address and HOPE the Highway Patrol won't harrass you, but usually the CHP DOES hassle and harrass people over this, unfortunately.

Oregon and Nevada plated cars the most.

Check the Bureau of Automotive Repair website too. The BAR handles the tests and they have a referee program you can go to, I believe.

Start here.

http://www.autorepair.ca.gov/

[MARINE_V]

Thanks for the O2 info guys, I did find it odd that they would 2 O2 censors. I think I might start there. I will order one and replace it, see if it helps.

@ Jim B. - I Live in Bakersfield California. Kern County some of the worst air in the country, we even have no burn days. So I suspect I live in a strickt smog area. But I been told that I could be so many things. I have a friend that has worked for Benz shops and she has a friend that I faxed my smog test results to and this it what I got back in an email from her.
I will share it with you guys.

"Hey you!! I feel so bad because I am running into walls to help you!!!! Mark received your fax today, He didn't have very good news =(. His words exactly were "this car is a mess". He said that you have a fuel mixture problem, your car is burning too much fuel. It is out of adjustment such as fuel mixture, co mix and timing...which you already knew.1st you have to start with that...then retest and see where you stand. He said you may have burned up your catalytic converter because too much raw fuel is passing through...as well as an O-2 sensor.

This is the problem....in order to do this it has to be done in steps...starting with the most obvious being all the adjustments and then reran on the smog machine to see how it affected your #'s on the smog test. If that takes care of it then you can resmog it...but if not then step two...rerun smog then so on and so on. So in order to do this Mark has to have access to a smog machine.....which he does during work hours. He may have been able to "slide it through" like on his lunch break....but because you already went in to inquire, boss may notice the car and could jeopardize Marks job. I have two other friends who know allot about MBZ and will do side jobs...but one said he wasn't interested because of year of your car. He said those are too hard to work on =(. My other friend Alex...he was interested but is moving this weekend so can't do it until MAYBE next weekend. I do have a few other friends I can ask but after some thinking I think this is what you should do.....

Call One Stop Smog on White Lane and Ashe. There is a tech there named Brandon who is really good on MBZ. You will have to pay a diagnostic fee...which does run 80-100 bucks BUT the good news is that they participate in a Government smog assistant program that you should qualify for that will (I believe) reimburse you your diag fee and pay for up to $500.00 to your repairs. You can call and talk to Michelle...and tell her I referred you if you want (she knows me cause I used to work next door at Euro) She can give you all the finer details about the program that I don't know.

I do think if you qualify for this this will be your best rought...IF NOT LET ME KNOW and we will one way or another get this worked out for you ok!

I*'m sorry that I couldn't be more help to you right now...but I hope this will get you on you way...without having to spend too much $$$$....ttyl, Love ya, Christy"

After reading all of this I am staring to think I should just cut my loses.

[glenmore]

My 1991 300CE failed smog last time around and it was the EGR valve. The repair was expensive but I qualified for the CA Smog assistance program. You qualify by simply having your testing done at a Test Only facility. IIRC the repair was ~$800, my share ~$300.

AFAIK, there is just the one o2 sensor. Acess to the connection is under the front passenger carpeting. I recently had to check mine, trying to run down a rough idle. Make sure your crimps are good and tight if you are splicing in a generic sensor. Generic sensor about $25 versus about $95 for one with the specified length wire.

[Merkey]

Next time put in a bottle of Iso-heet... we found it worked...

[Rahulio1989300E]

In case you need to replace the O2 sensor, here is a write-up I made for an M103ed W124.

http://www.peachparts.com/shopforum/showthread.php?t=271178

[MARINE_V]

Originally Posted by Rahulio1989300E

In case you need to replace the O2 sensor, here is a write-up I made for an M103ed W124.

http://www.peachparts.com/shopforum/showthread.php?t=271178

Thanks Rahulio1989300E, the car is going to the shop tomorrow. I hope the news is not too bad.

[MARINE_V]

Update on the car, just got call from shop. They stated that it was my catalytic converter. "Not getting hot enough" New unit $700 after market $350. They are replacing it and installing the new one hopefully it will pass smog this time.