Reducing Emissions Through Increased Cat Heating Technique

[gsxr]

The bulletin cure? A nice along highway drive in second or third gear.

<threadjack>

The same procedure (10 minutes at 4000rpm) works absolute wonders prior to your smog test. Since I started doing that as of last fall, I've seen the CO and NOx numbers near or at (!) zero on a three different M119 cars. Never had results that good previously.

500E: 16 HC, 0.04% CO
E500: 00 HC, 0.02% CO
S500: 13 HC, 0.00% CO

The M104 Gerrywagen is due for the sniffer this month, I'll repeat the process and see what happens.

</threadjack>

 

[gerryvz]

Re: external oil cooler opinions

I always drive my cars for at least 15 miles (usually that entails a run up Interstate-45 up to Conroe, Texas and back) before heading to the sniffer. My sniffer results are in my PWNER thread, but they are similar to that quoted above. Dave, you should have the TX and OR results for the Stigwagen in the paperwork that I sent you.

I have to take the SEC in for its annual test this month, too. It's now exempt from smog, so it's merely a $13 "safety" test to make sure that the tires have tread, the blinkers blink and the brakes work....

 

[gsxr]

Re: external oil cooler opinions

I always did the 15-mile drive before testing, but never at 4000rpm until ~6 months ago. The results were dramatically improved by the RPM increase. I was amazed.

I've got all your data on the Stigwagen's previous sniff results, I'll compare 'em after I have the test done this month! The last 5 years of tests from your records shown a range of 94-132 ppm HC and 0.16-0.46% CO. I'm not worried about it passing, but it would be cool to get one number or t'other down to zero, eh?

 

[gerryvz]

Re: external oil cooler opinions

I always did the 15-mile drive before testing, but never at 4000rpm until ~6 months ago. The results were dramatically improved by the RPM increase. I was amazed.

I've got all your data on the Stigwagen's previous sniff results, I'll compare 'em after I have the test done this month! The last 5 years of tests from your records shown a range of 94-132 ppm HC and 0.16-0.46% CO. I'm not worried about it passing, but it would be cool to get one number or t'other down to zero, eh?

After that amateur top-end refirb (particularly with the reversed front flex disc bolts and the reversed ground wire position), it's probable that the numbers will go UP rather than DOWN. I will be interested to see if doing a 2-3 gear revver will help things, and if so, by how much.

 

[samiam44]

Re: external oil cooler opinions

Always do it on a warm day and no rain. I pass with ease when it's >70-80 F outside.

Good emission test station locally, runs them through twice. Once in the test pattern is just to heat it up. Never passed at a quickly-lube place and they are unwilling to run it back through.



Michael

 

[SG-Motorsports]

Instead of driving all around and wasting fuel, you can just use a jumper wire to activate your air pump clutch and you'll pass with no problems. That's assuming your air injection system is working properly.

 

[Klink]

Instead of driving all around and wasting fuel, you can just use a jumper wire to activate your air pump clutch and you'll pass with no problems. That's assuming your air injection system is working properly.

 

[gerryvz]

In my experience, it's pretty bloody rare to hear of a 119 that doesn't pass emissions tests with flying colors. Darn things burn excruciatingly clean from the get-go as long as they are warm.

There was one time, some years back when I lived in Portland, when I drove my former black 1995 M104 wagon the two miles from my house straight to the emissions testing station, and it failed (just barely). Later that day I warmed it up properly, took it to another test station, and it passed with usual numbers.

So it is definitely important to warm them up. (10+ miles driven, preferably freeway or high speeds).

Cheers,
Gerry

 

[Klink]

Absolutely! If a warmed up stock Benz doesn't pass an emission test with light years of margin, something needs attention.

 

[gsxr]

Instead of driving all around and wasting fuel, you can just use a jumper wire to activate your air pump clutch and you'll pass with no problems. That's assuming your air injection system is working properly.

Just curious... would this work even on a car where the catalysts, ahem, "fell off"?

 

[SG-Motorsports]

Just curious... would this work even on a car where the catalysts, ahem, "fell off"?

Absolutely, That's when you need it the most. Like Gerry said above, if the cats are working like they should, there would be no need to fake it....

Of course this is only helpful if your emissions testers are as untrained as here in Washington state (state-run minimum wage job), because the air pump is typically quite loud and would be easily noticeable to a trained technician. I don't think you'd ever get this to work in California.

 

[Klink]

Lol. Georgia inspectors can't tell a center resonator on a European car from a catalyst, so most Benzes with the euro exhaust system will pass the visual inspection. Even when adjusted to factory spec, the emission level is low enough that they will pass the sniffer test as well.

Similarly, none of them would know or care whether an air pump was "working" or not...

 

[gerryvz]

I never recall even having a visual inspection for emissions equipment in Washington, Oregon or Texas. Definitely in Texas they don't care, as long as your car passes when they hook it up to the computer / sniffer. And I agree, no inspector (they are mostly pimply-faced kids here in TX) would even know what a smog pump sounded like, let along if it was engaged or not !!

As part of the TX state-mandated annual safety inspection they definitely visually inspect things like your tire tread remaining, whether your blinkers and lights are working, etc.

My biggest complaint is that you have to do it every bloody year, whereas in Oregon and Washington [and Spudland] we only had to do the emissions tests every OTHER year, and there was no state-mandated safety inspection.

 

[truls221]

In europe we have that bloody lambda value as well that must be within 1+-0,03

so any leakage will be seen on the test

i had major problems on mine with original cats (choked) after a misfire problem that burned the cats
then I mounted new ones, but after 2 weeks of perfect HC emissions (30-40 PPM) they didnt work any more (cheap cats)

the trick you describe gsxr will only work with 92 ECU, if there is no enrichment its very hard to light off the cats.
the problem is when going from enrichment to fuel cut, you will poison the cat and produce hydrogen sulfide
and if your cat stinks of "rotten egg" it will for sure bring attention to it.

the best results obtained on my 93 without enrichment is when starting from cold engine and driving carefully to the inspection.
then driving the last 100 m with full throttle.
sometimes when I failed the test they allowed me to go for another heat-up run, and typically the fall is 10-20 PPM.

if I ever get problems again with the emissions I would install the CO potentiometer.
sadly at least in Sweden, it costs as much as a few cats if you buy it OEM.

 

[gsxr]

Re: external oil cooler opinions

I've got all your data on the Stigwagen's previous sniff results, I'll compare 'em after I have the test done this month! The last 5 years of tests from your records shown a range of 94-132 ppm HC and 0.16-0.46% CO. I'm not worried about it passing, but it would be cool to get one number or t'other down to zero, eh?

Update:

With the cat-heating procedure done prior to testing, Stiggy (124.092 / M104) dropped down to 8ppm HC and 0.00% CO... a HUGE reduction compared to the previous 5 years of testing.

 

[gerryvz]

Probably just the result of last year's top-end refresh...