Failed SMOG

[humalag]

apologies for asking this question here...
i just bought '95 S420 and it failed California SMOG,
just trying to see if there is any way to tell by SMOG results what is more likely causing it to fail

 

[7delta]

I see it has some miles on it. Can you share any maintenance history? Can you share the previous smog report?
Last tune up?
original catalyst, 02 sensor?
How does it run...any misfire?
Has a compression check been performed?
What oil do you use?
Any information will help your cause.

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[Glen]

Looks like it's had some trouble passing emissions the last few years. Plug in the license plate here: https://www.bar.ca.gov/pubwebquery/Vehicle/PubTstQry.aspx

 

[gsxr]

The emissions limits where you live are crazy low. HC limits of 77 and 42? Are you kidding me? In other places with limits of 220, your HC numbers would have passed (and they don't always measure N.O.). There are several threads discussing smog failures, for example:

http://www.500eboard.com/forums/showthread.php?t=10492

http://www.500eboard.com/forums/showthread.php?t=10926 <-- start at post #23

Your spark plugs look good (tan/normal) but they are the wrong plugs, they are resistor plugs... should be F8DC4 non-resistor. The plugs are probably NOT the cause of the emissions failure though. As discussed in the threads above, the easiest thing is to try superheating the catalysts prior to test. If the O2 sensor is not recent, replace that next along with resetting LH adaptation. Check for vacuum/plumbing and intake/PCV leaks. The MAF could also be an issue but based on your numbers, I'd start with heating the cats first and go from there.

 

[humalag]

Thank for replies, I went to a different smog station today, just to lower human error factor, gave it a 20 min warm up at 4000+rpm prior, but still didn't pass, so I guess next step would be the O2 sensor replacement...
How big is the chance that cats are the problem? Can I drop em and tell if they good or not by visually inspecting em?

 

[Glen]

The high NOx readings indicate a lean condition. Look for a vacuum leak. Does it idle smoothly? How recent are the air filters?

 

[gsxr]

The cats are usually the last item to consider replacing (which is good, as they are not cheap). I don't know how to pinpoint the cats as the root cause without first ruling out some of the other items first (O2 sensor age, intake / vac leaks, etc).

I do find it interesting that heating the cats made a pretty substantial improvement in a couple of the numbers between the two tests, btw! Your car would have passed my local emissions test no problem... unfortunately where you live the limits are excessively strict.

 

[humalag]

Update: so I've stopped by another SMOG shop today, third one so far, and from what they told me the previous two shops were testing it wrong, on dyno vs on the ground stand still position, which makes huge difference in emission numbers, it would of pass if only an EGR valve was operational and wouldn't fail simple vacuum test, they advised me to just clean it and come back forretest, which I'm planning on doing tomorrow, I'll let you know of an outcome

 

[humalag]

E500, 500E also shouldn't be tested on a dyno in California, as it is not required

 

[captruff]

E500, 500E also shouldn't be tested on a dyno in California, as it is not required

That is correct since the 500E500 have non defeatable ASR. If your S420 does not have non defeat able ASR they may be inclined to test on a dyno in which case they will measure for NOx. That said I believe that post 1993 cars can be tested at the 2 speed idle test vs on the dump at the discretion of the smog technician.

Jeff

 

[nocfn]

In my local testing place, he wont test a MB or similar priced car on a dyno unless they don't pass the 2 speed test. (he had to pay several thousands for new rear end for a RWD MB when his Roller for the back (seldom used) malfunctioned.

 

[gerryvz]

My local testing place does the two-speed "sniffer" test for both my 4WD G-wagen and the E500. He has known me and my cars almost since I moved here 9 years ago.

Before it became exempt from testing a few years ago, the 560SEC was used on dyno with no problem. Never had a car not pass.

All of my cars will be exempt within the next 2-3 years, so it will all be a moot point anyway.


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[nocfn]

as a good customer with cat delete tri-y, he "thought" my coupe' was a diesel when he gave me a 24 year old safety inspection.

 

[gsxr]

... it would of pass if only an EGR valve was operational and wouldn't fail simple vacuum test, they advised me to just clean it and come back forretest, which I'm planning on doing tomorrow, I'll let you know of an outcome

Have you confirmed that the EGR vacuum plumbing is all intact and working correctly? If any of the vacuum tubes or fittings are cracked, the EGR valve may not open (but, this should trigger a CEL). Even if the EGR valve itself doesn't hold vacuum, if the diaphragm rupture is small, the engine vacuum may be adequate to still allow the valve to function normally. The valve itself isn't likely to need cleaning but you can remove it and inspect. If anything is plugged, I'd say it's more likely to be the metal pipe that goes to the middle of the intake manifold below the ETA.

 

[gerryvz]

If anything is plugged, I'd say it's more likely to be the metal pipe that goes to the middle of the intake manifold below the ETA.

+1. This is the more common issue, but I don't think that a non-working EGR is going to cause the car to outright fail an emissions test -- these engines burn pretty clean from the get-go.

Although I'd replace the O2 sensor as a matter of course (if you don't know that it's been done in the past 100K miles), unfortunately at 260K miles on the odometer, I think your issue is catalytic converters.

 

[Stevester 500E]

Bench test the EGR Valve. If it's good, then your EGR tube's end is clogged with carbon.

 

[humalag]

While I still didn't get it passed SMOG inspection, that EGR turned out to be working, it was a worker that runs that shop that didn't want it to pass after 3 back to back failed attempts and no evidence of repairs, so he was made it failed, he addmited that to me after
I still have till November to fix that or get rid of the car

 

[gsxr]

Can you take it to a different location to get smogged again? And make sure the cats are plenty hot by driving around at ~4000rpm for at least 5 minutes before arriving at the test station?

 

[humalag]

Finally it passed, the very same morning it died on me... It's rain season in Cali, and it was parked outside for a few days, started and took off no problem but then started having huge power loss and spurting and stalling. Couldn't start it right up but after it warmed up outside and wasn't that humid it started no problem, I decided to warm the engine up a little, so I loaded it with like 500lbs worth of heavy tools and drove on a highway on a 3rd gear at 80 for a good 45 minutes. And took it straight to the shop.
The only other thing that worth mentioning is the car had full synthetic change done.
Thank for all replies, I just thought this might help somebody in the future

It the one in the back of c class that I just sold to my buddy

 

[gsxr]

Interesting that the previous failures were both completely different tests compared to your most recent one. The first two measured NO, were at 15mph and 25mph (I assume on a dyno), and had crazy tight HC limits of 77 and 42 (which you still did not meet with the test dated Dec-2).

The recent test did not measure NO, was at idle and 2500rpm (no load), and had reasonable HC limits of 130 and 100.

Your HC numbers were abnormally high on the first fail (230 / 141), moderately high on the second (198 /91), and average-ish (80 / 80) for the most recent. I'd guess the 45 minutes in 3rd gear cleaning out the cats was likely what helped the most, but the more reasonable limits were a big part as well. Did you move to a new address with less stringent requirements, between February and now?

Regardless, thanks for the update and congrats on the pass!

 

[humalag]

I think mainly it is dyno vs no load test requirements. This whole SMOG thing is relatively new to me, so for the first 2 times I took it to cheapest shops, and Im pretty sure they just didn't know what they were doing, so this last time it was in the shop owned by an s500 owner
I guess he did his magic

 

[Oldcar]

Can you fail with nox 158... HC /CO around 80 in so cal? @ 2500 after passing low rpm test?

 

[Glen]

On my recent smog test, it doesn’t look like NOx was measured…


You can see the limits for HC at both speeds. This was here in the San Diego area on my ‘94 E500

 

[TerryA]

@Oldcar,
I don’t know where your at in SoCal but I have a Smog Guy in Orange/ElModena that knows Mercedes and has passed my 93 500E every two years since 2004. The test is I believe $83.00

 

[Oldcar]

On my recent smog test, it doesn’t look like NOx was measured…
View attachment 219131

You can see the limits for HC at both speeds. This was here in the San Diego area on my ‘94 E500

@Oldcar,
I don’t know where your at in SoCal but I have a Smog Guy in Orange/ElModena that knows Mercedes and has passed my 93 500E every two years since 2004. The test is I believe $83.00

How many miles on your 500e?

 

[Oldcar]

What's your .....mileage..
I've got over 200k 92 400e.....and you are correct they didn't test NO (ppm)

I can see from reading above that a very hot warmup is a key factor....remember Smog Guy sent me to frwy once after failed pre test and it passed....same guy charged me 38 for pre test on rollers ....that failed with no warm up recomend ..

 

[Oldcar]

@Oldcar,
I don’t know where your at in SoCal but I have a Smog Guy in Orange/ElModena that knows Mercedes and has passed my 93 500E every two years since 2004. The test is I believe $83.00

Does ho dyno it? Better if not correct,?

 

[TerryA]

@Oldcar,
In California the Smog Tech is not supposed to use the roller on the rear wheels on the Mercedes 500E and the test should be no different for your 400E.

If your Smog Tech is using the roller on the rear wheels he’s doing the test wrong. The car will fail.

 

[Glen]

@TerryA, Non-ASR cars are tested on the dyno.

 

[TerryA]

@Glen,
Thanks for the correction. I did not know that.

 

[TerryA]

@Oldcar,
I’ve read back thru your posts and could not confirm if your 400E has ASR. Can you confirm whether you do or don’t have ASR?

Anyway, Since I see your in Orange County if you need a good Smog Tech let me know.

 

[Oldcar]

@Oldcar,
In California the Smog Tech is not supposed to use the roller on the rear wheels on the Mercedes 500E and the test should be no different for your 400E.

If your Smog Tech is using the roller on the rear wheels he’s doing the test wrong. The car will fail.

Thanks for the information!
Don't think I have asr...

 

[Oldcar]

@Oldcar,
I’ve read back thru your posts and could not confirm if your 400E has ASR. Can you confirm whether you do or don’t have ASR?

Anyway, Since I see your in Orange County if you need a good Smog Tech let me know.

I have asr light on dash so I probably have ASR and no.more fake dyno rip offs..

Tech spent some time reading his manual and tested without dyno rollers that plus gentle fwy warm up showed almost completely in the green on the Smog computer screen at idle and 2500....so I think we may have this solved....with our shared info...!

Thanks to Terry and Glen