People I need your help in trying to get my 92 400E (170K Mi) to pass NJ emmision inspectoins. I just came back from the inspection station the only reason it failed was HC (hydrocarbon)too high of 102 maximum is 100. Other readings:

NOx not tested or no result indicated.
HC 102 max 100 FAIL
CO% 0.28 max 0.50 PASS
CO2% 13.9 no mximum indicated on report

test was at 2520 RPM wheels were not turning (not dynomometer).

I will tell the recent repair history of the car:
O2 sensor 2 years or ~ 30K mi ago
fuel filters 1 year ago.
Distributer cap, rotor, spark plugs, spark plug wires, and fuel pressure regulator, and injector cleaning 6 months ago. The current gas milage is on the poor side. any clues of how to address or reduce the hydrocarbon level? I hope you tell me to change the cat.

High HC is bad combustion.
Try cleaning the sparkplugs, give the car an oil change and then run it for 50 miles @ 70MPH (get that catalytic REAL hot before the test).
If that doesn't work, test the O2 sensor.

__________________
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

Cat seems to be causing low gas mileage....search for the post from Cap'n about his cat gutting and increased gas mileage. That also could account for your above maximum HC level.....but in order to pass the inspection right away, I also would get it really hot like pesuazo suggests. A bottle of 104 octane booster with a full tank of premium would also help.

I bought a car at the auction one year where the top speed on the highway was 60mph. My brother rode with me, and said I had just bought a lemon . I took it back to the shop, disconnected the exhaust from the engine, tied it up and went for a test drive.....with no one with me, I reached 120 mph on that Plymouth 400 Big block ex-highway patrol car. The difference in power even taking off slow was incredible!

Hope you pass the test next time! Good luck

__________________
'87 300E | 2.6 engine
Artic White - Navy blue interior, chrome rims, very clean and sharp!
91 300E
89 300E


The rest of my collection are just cars and trucks...no more "automobiles"...

You have a marginal failure and there is probably nothing wrong with the car.

Have the car retested. Make sure it is thoroughly warmed up with a half hour of driving including a freeway run.

Take the car to a place that will test it while you wait. DO NOT SHUT OFF THE ENGINE, BUT KEEP THE REVS AT 2000-2500 until they are ready to drive the car into the bay and hook up the test equipment.

Many Merc models will suffer marginal failures unless the converters are very hot, and extended idling before the car is tested can allow the converters to cool down and lose oxidation efficiency.

Did the printout list percent O2?

Duke

Rafi,
I'm not sure where in NJ you're located, but there's a fairly good shop independent specializing in mercedes in edison, nj. It's called "German car shoppe". Last year my 260E failed emissions for the same reason. I took it to the shop, they had changed the o2 sensor, changed the spark plugs and adjusted the other related components and the guy at the shop personally took it for inspection as well. They charge you 70 for inspection since the inspection is done at a private shop but it saved me the hassle of standing in lines and dealing with the attitude problem that I've had to deal with at some state inspection centers.
at the end my car was fixed and inspected as well.
good luck.

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

I went through the exact same problem you did, I was living the NJ , and when I took it for inspection on Aug of 2003 I failed emission marginally, a friend of mine told me to go to Pepboys and get a gas additive by the name. ( Guaranteed to Pass emissions). He said his BMW failed NJ inspection twice before he added that stuff. I was really skeptical, but I went ahead and did it , I also changed the spark plugs. ( there was nothing wrong with the other ones.maybe 5000 miles old) but I had to show the Inspection people that some work had been done. The car passed the emissions test with flying colors. I am a believer now!!!! My advice to you is go to an auto parts store and buy (Guaranteed to pass inspection Formula) It is available at Pepboy's , there are a few in NJ. I think you are going to have to fill out that form, to show what adjustments were made. I don't think it would be a good idea to show that all you did was add some additive.
Just follow the instructions on the bottle. I don't what it does but it works.

__________________
**A few Hondas etc... etc... Not Worth Mentioning**
83 Euro W126 380 sel Money Pit (Sold)
91 W124 300e 2.6. (Sold) 3.0 Motor is Much better!!
93 BMW E34 Touring Wagon (Sold) Sweet Car!!
91 300e (Just 200k with Ease.)Best car ever ???(Sold)
90 420sel (Black with Tan Interior) Best car ever!!!!!!!

Thanks for your help.

Duke2.6 There is a O2 section on the report but no reading or max or min.

Benz300 Edison is to far north for me. I agree with your assesment of the inspectors (they are supposed to be our civil servants, yeah right). I go out to the farm country where they inspect by appointment, there are no lines and the attitude is slightly better.

Theurig Yes I remember reading about it on this forum but I forgot all about it I should have added it before I went there, but next time, I will.

Since I have to show that I did something to repair the car, I will buy some air filters, plugs, etc. and try it again.

On the form that I have to fill out there are repaire catagories such as charcoal canister, I do not know if my car has a charcoal canister, I have not changed it in 8 years since I have owned it. Does that have anything to do with HC?

Another thing poped in my head, if the inspection is supposed to simulate driving conditions, If I did 2520 RPM on the road I will be traveling at 80 MPH, that is beyond the legal speed limit (65). Are they encouraging us to do 80 MPH or they suspect that we already do that and they are more realistic in their testing. Who came up with that number?

If you need work done and if Lakewood is closer to you (even if it's not I still highly recommend them) then go to Exclusive Auto. They're on Faraday Avenue in Lakewood, (732) 367-9090. Bob, the owner, and his guys know Mercedes (I think they're MB exclusive), are honest and do excellent work. They were highly recommended to me by a few people and now I won't take my car anywhere else. I'm not affiliated with them at all, but I am a happy customer.

I went through the same thing you did last month...my HC levels in my 300E were just a tiny bit high. What Duke recommended is correct but there are several things you can do.
1. Manage the test. Make sure you can keep the revs up in the 2500 range until the technician gets into the car to commence the test.
2. Clean your spark plugs.
3. I used the stuff you can buy at the auto parts store that you put into the gas tank before the test. It's a fuel cleaner and they guarantee that you will pass the test or they will refund your money.
4. An oil change would help too.

Good luck.

__________________
1987 300E
1967 Jaguar E-type Series I, 2+2

May I offer some friendly advice on using fuel additives to pass an emissions test.. I would only resort to using them as a last resort. Do all of the basic maintenance items listed above, check for pending fault codes, ensure all sensors have reliable connections, and test the emissions system if you have access to the appropriate scan tool. That marginal failure may also be a sign of an aging cat converter on its way out. Check the pre- and post-converter exhaust gas temperatures to rule that scenario out.

Only when all of that fails choose an additive from a reputable manufacturer.

Most of the so-called "octane boosters" and engine cleaners are nothing more than ethylene glycol (antifreeze), kerosene, and good old H20. If you understand their formulation and effects, you may be less likely to use them on a regular basis. Kerosene has a greater heat energy than petrol, causing the mixture to burn hotter during combustion. The irony is that octane "boosters" actually have the opposite effect, and may eat away at gaskets / fuel lines over time. Anyhow, enough about chemistry :-)

If you want a safer proactive approach to maintaining a clean engine, I would recommend Techron or a BG product (BG44k) between oil changes. And in my experience, raw aviation fuel in small quantities or Torco race fuel makes for a better track-only octane "booster"..

Hope that helps!

When they test at 2500 rpm & a dynamometer is involved, the transmission is held in 2 nd gear ( not top gear ).

__________________
2007 C 230 Sport.

OK manny how much time do we spend engaged in 2nd gear, do cars noramlly travel in second gear? no, they should adapt testing condtions to each car in terms of engine size. Yes 2500 RPM would make sense for a 4 cyl ~ 2 liter engine but not for a V8.

On top of that in the inspection pamphlet they go in detail of how important the NOx measurement for emmision testing is when they did not even do it on my car or at least they did not list the reading.

On top of that if your car fails they only accept work done by NJ mechanics, if the work is done by a mechanic from another state they do not accept it and they refuse to retest. What only NJ mechanics know whow to work on cars? It is good that there is a provision of doing the work yourself, I have not tested this yet. They may come up with some other excuse.

Gee, maybe you should move to Ontario, Canada.
As far as emissions testing goes, we wrote the book on how to do it ass-backward !
If you own a 4 wheel drive vehicle ( the worlds biggest gas-sucker ), your test ( due to the lack of any 4-wheel dynamometers ) is also only a " static " test. I.e. idle & 2500 rpm, no load.
In this test, NOx is also omitted.
As far as required repairs goes, you have to have them done at an " authorized " repair facility, to receive any credit.
From what I have seen of these " authorized " repair facilities, they all welcome customers at their door with the same slogan " Welcome sir....now bend over "! ).

__________________
2007 C 230 Sport.

I found previouse result os emission testing I thought it might be for interest to others as well.

year____2000___2002____2004____limit
NOx
HC______95_____98______102____100
CO%___0.23____0.19_____0.28____0.50
CO2%__14.4____14.9_____13.9____??
O2%
RPM___2382____2497_____2520___??

I do not know what RPM they are supposed to hold the engine at and what effect the RPM has on the readings. Failed for 2 lousy PPM over the limit.