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2011 GL 320 CDI, 2004 E320, 2000 C230, 2004 Toyota Sienna
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231 Posts
Discussion Starter #1
My 1990 300E failed emission.

Hc ppm Limit 52 Reading 17

CO ppm Limit 0.29 Reading 0

NO ppm Limit 578 Reading 615.

Failed on NO.

Replaced new EGR valve, tested manually. when vaccum applied at idle, runs rough.
REplaced cat.
Replaced O2 sensor.
Replaced OVP.
Replaced coolant thermostat ( antifreeze from radiator to thermostat)
Replaced antifreeze 50/50
Cleaned manifold and fuel system with 2 cans of sea foam via vaccum pods vaccum line.
Checked all vaccum lines.
Using 87 octane fuel (regular)

Car runs at 100 degrees to 110 degrees. Before replacing thermostat, it was running between 80-90 degrees.
Fans kick in.

Can I block (disable) vaccum to the ignition control module (on driver side passenger fender) to make it run little rich?

I am running out of options. I dont know how to use dwell meter method and dont have a dwell meter.
 

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89 300E; 00 E320
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2,515 Posts
They really are tough there, mine would have failed too. On the other hand yours would have passed here (GA, USA). Have you passed this test previously or is there any possibly way they selected the wrong vehicle in their system?

Allowed: 25/25 test....50/15 test
HC ppm..148..............152
CO%......0.94.............0.86
NO ppm..1047............1146

Some links that could be helpful:
Plugs?

Fuel mixture adjustment
Right/Clockwise to richen fuel mixture
And maybe O2 sensor and fuel adjustment process
07.3-1100 - Testing, adjusting engine

Why not premium gasoline?
 

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85 300 TDT
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2,260 Posts
First of all this is not a fix, just a way to pass your emissions when the NO2 is high.

Take it down to half a tank and add a liter of 70% rubbing alcohol. Run it for 10-15 minutes and end up at the testing station.

Worked for me on my W201 and was recommended by my old-school mechanic.
 

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Premium Member
About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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5,466 Posts
I had high NOx readings on one of my 88s and that year doesn't *have* an EGR valve. I replaced a bunch of parts that were half shot but that made virtually no difference in readings. Tweaking the duty cycle setting made a magical difference and the NOx numbers dropped.

I think you're going to have to mess with the duty cycle setting to solve the problem. You don't need a dwell meter. A digital VOM will do the job. Search the forum for details as I'm not up on it. I use a dwell meter.

And use better gas. 93 is probably overkill but 91 would be okay. At the very least use 89 octane. The engine's compression ratio is 9.2:1 and fuel delivery/ignition control are pretty primitive. 87 just isn't going to cut it.
 

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1992 300ce, 3.0, 207,00 mi.
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335 Posts
But is your EGR valve opening when it should? Get an inspection mirror, flashlight, and a helper. 1st ck yo make sure your getting vac to the valve, disconnect vac tubing have helper rev eng to 2000-2500 rpm and you should sense a vac. Reconnect vac tubing and with flashlight and mirror position it so you can see under diaph part of valve, have helper rev eng as before and you should definitely see the valve opening. It moves quite abit so you can't miss it. Just smogged my car, NO was really low, failed on the 25 mph HC, max is 57ppm and my result was 59ppm. CA is the worst!
 

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2008 E350 4M, 2016 Audi Allroad, 2019 Audi Q5
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5,445 Posts
Well the fact you are using 87 gas (why?) isn't helping. If you are using 87 gas to save money, the W124 series is probably not the car for you.

91 Premium, run the car at 4k rpm on the freeway in 3rd gear for about 15mins before you get the test done and put 2 bottles of ISOheet in the tank. That should tip you over the edge.

Also why is the car running at 100-110? Is that C or F? I really hope that is not C...

Is your oil fresh?
 

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2005 E320 4MATIC, 1994 E320, 2000 Ducati M750
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135 Posts
Have you checked to see if you can get a waiver for emmisions? Here in Massachusetts, they did away with emissions last year on anything 1995 and older, which saves me, but before that if you failed twice, and showed you spent ~$250 + trying to correct the problem but still failed then they waived the test. Our cars have never been good with emmissions, my 1986 never ever passed, even once. Every time I took it in to retest the station would usually chuckle and just say, "Its an old Benz, they never pass LOL"
 

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2011 GL 320 CDI, 2004 E320, 2000 C230, 2004 Toyota Sienna
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231 Posts
Discussion Starter #9
Thank you all. I took the car to a certified emmission garage and they found out that the 3 month old catalytic converter was defective. They repalced it and the car passed with good numbers. It was a Magnaflo cat and because it was welded, they would not honor the warranty. I bit the bullet. They told me that regular gas sometimes works batter than premium with 2 bottles of gas antifreeze (like heet). One headache is over. Regards.
 
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