1989 300e failed ca smog!!! Yikes! - PeachParts Mercedes-Benz Forum

socaleuro · #1 02-18-2009, 02:00 AM

Took the 300e to the test only today and wow...I have never seen suck high ratings. Then again, I have never owned anything this old.

@15mph RPM:1637

HC:183 -FAIL (max is 110)
CO:1.46 - FAIL (max is 0.71)
NO:411 - PASS (772)

@25mph RPM:1437

HC:193 - FAIL (max is 85)
CO:1.52 - FAIL (max is 0.59)
NO:541 - PASS (max is 711)

Has anyone had any experience with this or even know where and how to start taking a stab at it? Thank in advance to all!

Jim B. · #2 02-18-2009, 06:46 AM

I think the idle could be waaaaaaay too high, at 15 mph, for your 6 cylinder.

Because for a V8 560 for instance, 650-700 rpm at idle, is on the money.

Avoid at all costs, an actual test where the result gets reported as a "Gross Polluting vehicle", that is a horror.

Generally speaking, Mercedes Benz gassers of that time burn very clean, if in good tune, at 139k mine, a 1991 California spec Mercedes Benz has never ever failed to pass a California smog test, not even once, in its whole life.

mbdoc · #3 02-18-2009, 08:03 AM

Either the O2 sensor is not working OR the mixture is so far out of adjustment that the O2 sensor can't work.

Chadahar · #4 02-18-2009, 08:41 AM

Have you done your maintenance? New plugs wires dist. cap and rotor. Fresh oil change and NEW FILTERS. Did you warm the car up for 20-30 minutes before you took it in?
You just can't take these cas from a cold start into the test with NO preventive Maintenance. Just cuz it passed last time doesn't mean jack this time ...as you found out.

BTW I think your EGR is working well because of the low NO readings. Change out the O2 sensor. When was your cat last changed ?

anziani · #5 02-18-2009, 11:37 AM

Hi,
My '87 300E with 204K just passed with no problems.
Anziani

'87 300E 204K (just sold)
'95 E420 115K
'93 300CE 160K (just bought)

pawoSD · #6 02-18-2009, 02:39 PM

On that motor everything depends on whether or not the O2 sensor is working and if the CIS system is adjusted properly....if its not....you'll be wasting gas and polluting...

socaleuro · #7 02-19-2009, 04:00 AM

Yea, I was leaning toward the O2 censor... Anyone know the way to check voltage or tell if the censor is working? I really think its running rich, by a bunch.

As far as a high idle goes, in P/N/D idle is within spec. The car was run for way more than 30 minutes before hand. Everything is done but the cap + rotor, but I really think its too rich. Also, there is no EGR on this car.

Thanks everyone, keep 'em coming!

Chadahar · #8 02-19-2009, 02:18 PM

I would take it by my favorite Indy and have him set the CO, mixture and idle. A generic 02 Sensor is only about $40.00 USD here in So Cal. If you need a good Muffler guy I have one in Lancaster, CA. He uses Bosh Generic O2 sensors and they work and are inexpensive.