91 300E Failed Smog Test by 5000% - Page 2 - PeachParts Mercedes-Benz Forum

400Eric · #16 03-07-2010, 06:22 AM

Update please. Numbers from smog retest.
Regards, Eric

JohnM. · #17 03-09-2010, 06:36 PM

WOOHOO. Go team.

HC GPM: 3.49 (Limit 1.5)
CO GPM: 117.019 (Limit 20)

JohnM. · #18 03-09-2010, 09:00 PM

I'm going to check duty cycle and read the EHA mV tomorrow. Otherwise I have no idear. The new O2 sensor cleaned up all of the weird stumbles/issues the engine has had since I bought it. Not so quick to blame the CAT just yet. Again, it did not fail at idle or at cruising RPM. It fails massively on acceleration. There's obviously something VERY wrong with fuel enrichment.....

400Eric · #19 03-10-2010, 06:20 AM

I'm following this because both of the M103s in my sig just barely passed their most recent smog tests. Having 232,000 and 194,000 miles on them doesn't help any.

This is so out of left field but I have found that these CIS-E ECUs can kinda go south yet still seem kinda OK. I would never recommend anyone to just throw parts at a car but M103s are so plentiful out here in the U-Pull-Its these days that it's just too easy to get stuff cheaply and do a little experimenting. Any unused good parts are always good to keep as spares anyways. Most recently, I cured a high idle problem with an ECU change on the 89. Disbelieving, I put the original ECU back in for a week and the high idle problem immediately returned. Just remember to stay with 90 and later 3.0 M103 ECUs only as pre-90 ECUs aren't the same.
Regards, Eric