Had previously posted that my 1986 300E miserably failed the Ontario, Canada, clean air test --a day later decided to just run it through a second time and it passed. What gives?

My guess is that the cat was cold for the first test, which caused the no pass. For the second test the cat was likely warmed up and doing its job.

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Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

First of all sorry in original posting meant 300E and not 900E - was thinking of my Saab 900T. Anyways is there a way to adjust the air fuel mixture to make the car run a bit leaner? The tech that ran my successful clean air test told me that my car seems to run very rich and joked by saying that I must drag a fuel tank behind because I must get awful gas mileage - I have checked my fuel consumption and on the highway cruising at between 120 km/h and 140 km/h it seems to get aprox 22 mpg - is this OK for a 300E

hey... I also have a 300E and Saab 900T convertible... Great cars, am only driving my benz now..22mpg is great for a 300E

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1993 Lexus SC300
1987 Mercedes 300E ..totaled out..
1991 Saab 900Convertible ..gave away..

Darn! I was hoping you'd post some pics of that 9.0L engine you got in that thing!

BTW, does your smog pump work in your car or is it disabled? It's sole purpose is to inject air into the mixture during warmup (while the cat is still cold) to keep the mixture smog-legal until the cat can do its job.

In Europe, their smog inspections require exhaust sniffing within 60 seconds of startup...so the smog pump is essential for this. Here in the states, it's not necessary.

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Hello,
Would the car run better and get better fuel economy without the smog pump? To disable and test without removing and pluging hoses--- can the elect. connection just under the washer fluid reservoir be disconected?

Once the engine is warmed up and goes into closed loop operation the Lambda system maintains stoiciometry. Their is an initial adjustment on the fuel meter that can be checked and adjusted as necessary to get the base mixture in the middle of the range by checking the "duty cycle", which has been extensively discussed on this forum.

To gain more insight into the emission controls and how to manage your test to ensure the highest chance of passing and how to get a marginal failure to pass look at the following thread and also the link in this thread to a second thread.

http://www.peachparts.com/shopforum/showthread.php?p=833484#post833484

Duke