Failing smog test in CA - PeachParts Mercedes-Benz Forum

dunga · #1 03-09-2006, 02:46 AM

Fellows,

I have an 87 260E and I am having a nightmare getting it to pass a smog test in California. The problem is that it spews smoke out of the tailpipe and though it passes at 25mph, it fails at 15mph and I am wondering if my engine is no good. I tuned it up, put synthetic oil in it, and changed the Catalytic converter and I still fail. The HC is off just a bit at 15mph.

If anyone can help me out with tips or advice, I would really appreciate it.

dieseldiehard · #2 03-10-2006, 02:32 PM

Quote:

Originally Posted by dunga

Fellows,

I have an 87 260E and I am having a nightmare getting to pass a smog test in California. The problem is that it spews smoke out of the tailpipe and though it passes at 25mph, it fails at 15mph and I am wondering if my engine is no good. I tuned it up, put synthetic oil in it, and changed the Catalytic converter and I still fail. The HC is off just a bit at 15mph.

If anyone can help me out with tips or advice, I would really appreciate it.

What part of the State are you in BTW?
Automatic transmission I presume?
Your experience is why I drive diesels, ha! Is the thermostat working? Changing to a hotter thermostat will reduce emissions, as will adjusting the timing.

A gasoline engine is a complex one that takes some skill to understand what affects emissions.
Please don't ask me as I am not an expert but I know from experience that normally, if there isn't a serious engine problem a shop should be able to make minor adjustments to get it to pass. Visible smoke out the tailpipe indicates something is wrong and you may need to do diagnostics at another level (compression measurements or a leakdown test, etc) to diagnose the source of the smoking.

dunga · #3 03-11-2006, 03:27 AM

Thanks man. I am in Northern CA, the Bay area. The car is indeed automatic and I will try a hotter thermostat and I will post the result. The compression starts at 120 and climbs to 150-160 which I think is not bad for a relic.

iwrock · #4 03-11-2006, 11:44 PM

I think that there is a way to tune the amount of fuel you get into the engine. I would do a search, and see if others have sucessfully been able to lean out the mixture a bit.

Also, I know of a good shop in the Bay, but I cant remeber the name of it. I will think and let you know ASAP.

dunga · #5 03-12-2006, 02:22 AM

Looking forward to hearing from you. Thanks!

dieseldiehard · #6 03-13-2006, 04:23 PM

Try the MB Garage in San Mateo if you can't find something closer to you. Tel 650-349-2744. They have a gas analyzer and the know how to troubleshoot that engine. There's also a smog check outfit right next door.

EDIT:
Larry and Janet at
MB garage
2165 Palm Ave
San Mateo, CA 94403
phone: (650) 349-2744

dunga · #7 03-15-2006, 02:09 AM

Thanks a lot. I will try the number you posted, hopefully something will give. I will keep you posted.

dunga · #8 04-07-2006, 02:15 AM

Fellows,

I still have not managed to figure out what the problem is, I am afraid I am stuck unless some good samaritan out there could throw me a lifeline. I am deseperate. I need to do a change of ownership smog test and the State has no assistance programs for my case.The HC are off just a bit at 15mph, everything else is OK. I am thinking about disconnecting the fan and running the car real hot just before testing.

dunga · #9 04-10-2006, 02:53 AM

Actually, I recently bought the car and the seller normally smogs it before selling, unfortunately, he did not. The State has programs for biennial smog check only. I could sue the guy I bought it from but I really prefer to exhaust all avenues first.

Ashman · #10 05-05-2006, 02:52 AM

I would try doing a few things.

1. check the spark plugs and replace with original bosch standard copper core plugs if needed.
2. Run the tank until almost empy, then run some fuel injector cleaner through it with a 1/4 tank of premium and run that until it is gone and then fill up again with premium.
- you can also try to find some stuff called bg44k which supposedly will give the engine a very good cleaning. I myself have not used it, but do some searching on the forums.
3. Drive the car for at least 20 - 30 minutes at high rpm's (also known as an italian tuneup) hopefully on a freeway in like 3rd gear to get the cat nice and hot. then take it in for the test, and don't let the car sit and cool down for too long before it is tested.
4. Make sure you have changed the oil and filter and that it is nice and clean. also check your air filter and make sure it is not dirty or somewhat clogged up.

My car always fails if it has sat too long before they get to testing it. but the place I go too will always run it again right afterwards and it always passes then. the guy even told me these cars need to be really warmed up and hot. When it is in that state, it always passes with flying colors well below the max levels.

If all else fails, try some of the guaranteed to pass stuff they sell at auto parts places.

Definately search the forums, because this topic has also been covered quite a bit.

dieseldiehard · #11 05-05-2006, 08:36 PM

Another thing I thought of! Try another smog place, tell them you want a Pre-check only and then see what the percentages are. If OK then you pay them (again) to get the smog permit. If you don't clarify which you want they usually assume you want a full smog chec and go for a permit and its too late once they have the data print ou its already been reported to the smog police automatically (on line).
I've known Volvos with a hot wire MAF that will not pass if there is a fan directed on the front of the car during the measurement, but OTOH I know of a Mercedes that failed pre-check unless the fan was on, exactly opposite to the Volvo. Figure that one out!
A hot engine will burn cleaner and additives help so try everything then move on and good luck.
If I had one I would install A Crane optical points or a Pertronix AND a CD ignition like the one I have on my 115 gasser on it. Then I bet it would pass (and run a whole lot better too!) Just don't show me the car because I have some vulturistic thoughts (something to go with a five speed)
DDH

dunga · #12 08-19-2006, 04:02 AM

Thanks diesel, I am still failing man and I am going to keep at it until I pass. I will let you know when and if I do.

cdplayer · #13 08-19-2006, 04:14 AM

I appreciate your determination. I found my 500 SEC in Seattle. Flew up and drove it home. Sweet. But it too failed at smog. Had all the California smog equipment on it as it entered the country at San Francisco in 1984. I am here in Sacramento. I went to a smog only and it failed. Took it to a smog repair and they put in a new oxygen sensor. Problem solved this time. They told me the cat was tired so all my change is collecting in a big jar for a new cat down the road.

Hope this helps. Good luck.

iwrock · #14 08-19-2006, 06:32 AM

CDplayer, where are you at in Sacramento?

Anyways, I know how it feels about the Ca. emissions. I just had to smog the wagon, and it failed terribly. I had a new cat put on, and it passed with flying colors!!!

blue · #15 08-24-2006, 08:44 PM

I have a 1986 190E that failed smog a couple years ago. My former shop de-carbonized the engine and it passed. The car is not a burner to begin with so I was surprised it failed. Depending on where you're located you could check with Barooni Imports and ask for George in Mountain View. Or, you could call Marshall at Silver Star in Oakland (510.834.1090). He's a dismantler and service shop who's been at these cars for 30 years. Another place in Oakland is AllMercedes at allmercedes.com. But, Marshall could tell you whether or not you got forked and probably what to do about it.

EDIT:
Barooni Imports Auto Sales
1905 Old Middlefield Way
Mountain View, CA 94043
(650) 969-4400
http://www.barooni.com

Marshall at
Silver Star Motors
1727 17th Street
Oakland, CA 94607
phone: (510) 834-1090

All Mercedes
1225 7th Street
Oakland, CA 94607
Monday-Friday: 8:00 am - 5:30 pm
Saturday & Sunday: CLOSED
Tel: 510.763.8602
Fax: 510.444.2345
http://www.allmercedes.com