Failed Emissions HC + NOx....Any ideas?
 

I looked at the photos before I went and it was clear -- got there 10mins later and 4 huge commercial trucks and a camper van so sat in line for 20mins which really pissed me off and I am sure affected results a bit.

I have NOT done anything with the fuel or ignition system since last smog so not sure why everything was drastically different:

BEFORE: 6/7/2011
300TE // limit // result
HC: 0.18 // 1.60 // PASS
CO: 0.69 // 15.00 // PASS
NOx: 2.38 // 2.50 // PASS

TODAY:
http://www.w124-zone.com/downloads/p...ssions2013.JPG

Any ideas on where to start? All #'s went up a large amount...so I don't know where to even start.

List of recent fuel/ignition items:
Current Mileage: 132,000
O2 sensor 2008 @ 75k
Distributor Rotor + cap 2008 @ 70k
Injectors 2009 @ 94k
Fuel distributor + EHA rebuilt and flow tested in 3/2011
Spark Plugs 6/2012 @ 106k (will replace)
Air Filter 2011 (will replace)
Spark Wires 2009 @ 85k
Fuel Filter 2011 @ 106k
Oil Change @ 128k (will replace)

Throw in two 2.5 oz. bottles <below pics> of RXP fuel additive - and your car should pass with flying colors. RXP provides a more complete combustion, and should get your car passed. It works here in DFW getting cars to pass the annual emission state inspections. O'Reilly and perhaps other auto supply retail stores sell it. Each 2.5 ounce bottle treats 10 gallons.

Report back on results please?

.

I'm not a believer in the throw a bottle of X in and you'll be good... :-/

What kind of mileage are you getting?

https://www.fuelly.com/driver/ps2cho/300te

6k miles tracked about 21mpg average. About as best as I've ever had with this car. Mostly freeway however...

Well, you can always take it to your Mercedes-Benz dealer's service dept.... :-/

High HC - Bad cat?

The CO went up by the largest percentage. That tells me that its too rich. The h/c didn't increase by a whole lot so that extra fuel is burning in the catalyst. That is making the catalyst run really hot causing the rise in NOx

Figure out where and why there is extra fuel and you'll fix the problem. Fuel dist plunger, and EHA are where I'd start looking.

Your TE seems to have problems with every emission test. Did you ever follow my advice to alter the spark advance map temporarily by shorting the R16/1 connector and blocking the vacuum advance.

IIRC you have an aftermarket converter, which could be an issue. They don't seem to last very long, but if you recall my test results, the above temporary mods cut my HC by nearly 50 percent and NOx by 90 percent.

Duke

I agree with the others. You are burning too much fuel. My 300 gets that much in city driving. I've gotten as high as 25 on road trips.

Only reason I am not 100% sure about running rich is that I was getting this mileage before when I had 0.10ppm on HC.

I will do a little catchup on the ignition system -- Rotor + Cap, BP5ES (BP5EF) plugs, and splice in a new Bosch 13953 O2 sensor since all those items are at or very near recommended change intervals.

Duxthe1: I had the fuel distrib + eha rebuilt by larry @ CISFlowTech 2 years ago so I can guess everything with those 2 items should be OK. I guess I will run a fuel pump volume test to make sure everything pump-side is OK. Once all that is done, I will check mixture and make sure its not showing rich as you suggest.

Duke -- I thank you for the help at the prior emissions. I managed to get it to pass with the R16/1 shorting...but BARELY. Shorting it did not give me huge differences, so this time around I left it alone to see how she would do as-is.
I am also concerned about the Magnaflow cat. I had it installed in 2008...so its been 5 years and I do not have any precats so its fronting everything itself. Its a dang shame you can't "just" buy the OE cat and install it -- you have to cough up $2k for the entire pipe which I just simply cannot afford, nor is it cost effective.

Plan is to do the above, and then gauge results afterwards to see if I should get the Magnaflow replaced. Sucks emissions is a little bit of a crapshoot since everything is somewhat inversely proportional so nothing is ever 100%.

For my wife's Honda (1990 Accord LX), a number of items were replaced and it passed like a new car. Pre-test numbers; HC = 72ppm and NOx = 536. PCV was toast as was air-filter, original O2 sensor and, original cat @ 148k miles!

Direct link here. Unfortunately, replacement cats have a very short life so I'm told.

Make sure you plug the vacuum advance signal line to the EZL module, too.

Unfortunately a lot of owners replace the OE catalyst way too soon IMO. Catalyst aging increases the temperature required to achieve maximum oxidation/reduction reactions, but retarding the spark advance map really helps by reducing engine-out NOx dramatically and increasing EGT to get the cat really hot during the test. The hotter the cat, the more reactions it will enable.

In the California ASM test the 15 MPH segment is done is second gear (I have a five speed manual in my '88 190E 2.6), which is about 1500, and with the R16/1 connector shorted and the vacuum advance blocked, no advance is added to the 9 deg. initial.

I always ask them to do the 25 MPH test in third, which is also about 1500, but sometimes they do it in second, which is about 2600. The numbers in both cases are about the same even though there is more advance at 2600 - probably because the 15 MPH test gets the catalyst very hot.

I believe your test is I/M 240, which has more speed and load variation, but retarding the spark advance map should have similar results assuming the cat is in reasonable working order.

The problem with my car was high HC at 15 MPH. It never failed but was at 90+ percent of the cutpoint. What really surprised me is the dramatic reduction in NOx. NOx is produced in the flame front at over 4000 deg. F. If timing is optimum for maximum torque at a particular operating condition, peak combustion temperature is about 4500F, but reducing it a few hundred degrees can dramatically reduce NOx formation. This is what retarded spark advance and EGR do - reduce peak combustion temperature.

Lower peak combustion temperature also reduces torque output, so where does that energy go? The First Law of Themodynamics says that energy is conserved. We have to accout for it, and that energy which would otherwise produce torque ends up going out the exhaust in the form of higher EGT, which adds more heat to the coolant as it passes out the exhaust ports and heats up the catalyst.

Duke

Will plug it when I get the retest done...still gotta do a little catchup first.

Here's a start in the right direction...Along with a few other goodies. And no that box does NOT say URO!!! :D

http://www.w124-zone.com/downloads/p...mog/parts1.JPG

Here is probably 90% of the problem:

Plus why you don't buy ANYTHING but OE idle valve hoses. These are 4 years old and before I understood the reason why you get OE rubber parts. They crack out of sight. I didn't even see that slit until I uploaded these photos, I just saw the hairline cracks. Its split. This can leave you stranded on the freeway!

Plugs are older than I thought too and you can see the difference in plug gapping compared to the Denso next to it...must have got mixed up on my maintenance excel doc.

http://www.w124-zone.com/downloads/p...smog/smog1.jpg

http://www.w124-zone.com/downloads/p...smog/smog2.jpg
http://www.w124-zone.com/downloads/p...smog/smog3.jpg

Plus you can never seal this damn timing cover lmao. I used the OE paste and did it with perfection...yet 10k miles later it still weeps a little :-/
http://www.w124-zone.com/downloads/p...smog/smog4.jpg

Does that rotor mount thing just pop off? Or is there a release on the inside? I was at a junkyard a while back and couldn't get it off. I think it was just stuck but I couldn't remember how I got it off years ago.

There is one Allen bolt through the middle and you gotta work it out slowly. I think over time it expands and fights you upon removal. There is an updated part # for it that corrected some that sheared off.

Well...much better, but still back to the borderline NOx failure I had last emissions check 2 years ago. I did the r16/1 resistor short and plug ezl vacuum...

Any ideas if the mixture looks about right now? I set the x11 @ ~46%.

So the below shows with new plugs, rotor, cap, o2 sensor, air filter oil change and mixture reset.

http://www.w124-zone.com/downloads/p...smog/smog2.JPG

Any suggestions from here?

FWIW...I did notice they ran the test twice. I believe after they did the same thing last year, if one variable is within a certain margin, they re-run the driving test. The first failure they did NOT run it a second time, but this time they did. Last year on both borderline failures, they ran it twice. So I when I saw them run the test again, I thought to myself OK its gotta be CLOSE!!

On a happier note, I spilled about 3 gallons of oil all over the floor, and took the opportunity to hose down, simple green, scrub with a big broom and rinse off the garage floor. Looks beautiful now! :)
http://www.w124-zone.com/downloads/p...aragefloor.JPG

I just looked and I did take the screw out. That piece got completely stuck in my parts engine. Weird because I knew I was doing it right.

It looks like you got the main offenders. I would give it an Italian tune up and try again. Sometimes the m103 just needs a bit of time to adjust to the new parts.

Start keeping track of your mileage now. You will probably notice a significant improvement.

I ran it at 80-85mph for 15miles then held 4-5k rpm 2nd gear for the remaining few miles (luckily its off some back road in the desert so no cars around)...so it definitely got the italian tune up. Once again photos showed no cars and I pull up to 2 in line. I bet had I not sat for 10mins, I would have passed, albeit still borderline.

Something else is amiss here...

Was the 2011 test with the OE or replacement catalyst?

Is the replacement catalyst a proper three-way type, and is it approved for your car?

Do you have any test results dating back to when the car had the OE catalyst to compare with current test data?

Even in 2011 NOx was near the limit. Also, the NOx limit seems low for a 1988. I know of one case in California where the CARB screwed up and set too low a limit on one gas, which caused a lot of grief.

Shorting the R16/1 plug and blocking the vacuum advance reduced NOx on my '88 190E 2.6 by 90 percent, but my problem was HC close to the limit, which was reduced 50 percent. Given that both our engines have the same basic emission control setup, I don't understand how your NOx is so high, which is why I am questioning the standard.

California's test report lists averages for the year group. I suggest you contact your emission test authorities and discuss this issue with them. Is there a high incidence of NOx failure in your year group, and how was the NOx standard established?

Duke

2011 result with the same replacement cat.

Maybe its simply because I have no precats and that takes the NOx load?
I do notice though when temperatures rise, the car gets much slower...is that normal due to timing?

Here is the one I have:
MagnaFlow Catalytic Converters - 49-STATE & CANADA Catalytic Converters For Trucks, Suv's, American Muscle, Diesel, & Sport Compact Vehicles
http://images.magnaflow.com/02product/parts/93507.jpg

http://www.w124-zone.com/downloads/p...swap/swap2.jpg

Let me dig my paperwork and find some old California test #'s before I had the cat replaced...

Found them quicker than I expected:

My old 87 260E got these numbers in 2011 Arizona emissions it had OE cat and precats very similar maintenance history (did idle better than my wagon does though):
.......Mine // standard
HC: 0.31 // 1.60
CO: 5.42 // 15.00
NOx: 1.25 // 2.50

Here are the wagons: Note the high 02 -- that's why I got the cat replaced. It barely passed...This was my last California Emissions I did before I moved to Arizona in 2011:

http://www.w124-zone.com/downloads/p...g2009wagon.jpg

My understanding is that the precats just below the exhaust manifolds are oxidizing only and are supposed to reduce warm-up emissions, but without supplemental air injection I don't see how they can do much. Maybe that's why they disappeared from later M103s.

There's no useful technical data on the Magnoflow catalyst other than it is 49-state and Canada. I believe aftermarket cats have to be certified with the California BAR via a test program, so I expect this catalyst in not CA approved, and I have no idea if it is two or three-way, but most replacement cats nowadays are three way since they have been nearly universally used by OEs since the early to mid-eighties.

You last CA ASM test shows high HC and NOx at 15 MPH relative to 25 MPH. That's probably the result of catalyst aging. It was degraded and not hot enough to enable all reactions during the 15 MPH test, but heats up enough at 15 MPH to do much better on the following 25 MPH test. The high O2 content means that the catalyst is not operating at maximum efficiency; 0.0 percent O2 means that it is.

My recommendation back then would have been to keep the OE cat and tweak the spark advance map per my recommendations to give you more margin. The OE cat should only be replaced as an absolute last resort.

With the R16/1 plug shorted and the vacuum advance blocked, the engine will be extremely sluggish below about 2000 revs. EGT will go up which heats up the catalyst, but it also throws additional heat into the cooling system as exhaust gas passes through the exhaust ports, so hotter running in low speed driving is normal.

During my recent CA ASM test the auxiliary fans did not come on during the test and the temp gage was at about 100C when he drove it off the rollers and shut it down. Five minutes later when I stated the engine to drive off the temp was about 110C due to heat soak and the aux. fans came on immediately, but cooled it down to 100C and shut off after about 60 seconds. I drove the couple of miles back home and immediately returned to my normal spark advance map - no resistor in the R16/1 plug and normal vacuum advance function.

I'm out of ideas, but I still think you should talk to your state emission test administrators - equivalent to the CA BAR - and find out why the NOx limit is so low and the percentage failures in your year group.

Duke

I threw 5 bottles of ISOheet in 1/2 tank of gas and it did the trick.

http://www.w124-zone.com/downloads/p...smog/smog3.JPG

Until next test, I will chip away at more stuff and see if I can nail it first time then :)
If I ever get some time, I will contact the state and ask about failure rates for this model, particularly on NOx.

Was the ISOheet in the tank during the inspection, or did you run it through the engine, then fill up and redo the inspection?

Bump
 

?

What about the RXP fuel additive

In the tank. Its supposed to be burning in the combustion chamber during the test. The higher concentration the better.