This morning, I started down my street (after about a 2 minute warm up) and got to the stop sign. It was about 70 degrees and very humid. I felt a little shake and when I went to step on the gas, only a little more shake - and the RPM's were almost under 500rpm. I hit the gas again and it "woke up" and has been normal since. I am due for a transmission service (ordered all the part this week) but other than that, all has been well. I do notice that my curb idle seems to be around 800 rpm regardless of the AC on/off.
Air filter was done about 5k ago.
MAF has not been touched.
No codes or error lights when this happened.
Oil change last weekend.
My E430 had the same behaviour a while back. It was the 2 front O2 sensors. I didn't have a CEL but I did have 'O2 sensor aging' codes. Replaced the sensors and the car has been fine since.
Did you plug in a scanner to read any codes (pending or actual)?
I have not thrown a reader on it yet. Going to have to make a run to harbor freight later... I do have access to a CAN EOBD II reader - will this work?
Our ML320 has done this a couple times... haven't had it diagnosed yet...
If you make a habit of "warming up" the car, I would change that habit... Mercedes designed the cars to be driven moderately within 30 seconds of starting... there is an air pump that is activated for approx 1 minute after start that aids with emissions... the car also holds gears longer (which feels wrong, but it's completely correct) to heat up the cats quicker.
You are also wasting fuel as well as not allowing oil to circulate through the engine as it would at full pressure while driving.
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2000 C230K -- Travertine Beige Metallic
2002 ML320 -- Alabaster White
2002 ML320 -- Brilliant Silver - Dad's
1991 300CE -- Blue Black Metallic -- 129,000 miles -- Sold
1981 300SD -- Classic White -- 190,000 miles -- Sold
1977 240D -- Over 300k miles (Wrecked) -- My 1st car
I do generally get in and go - except when it's minus 10 degrees (F) here, then I let it warm a few - more for me than the car. I threw that 2 min warm up in as it was the exception to my routine this morning.
My E430 had the same behaviour a while back. It was the 2 front O2 sensors. I didn't have a CEL but I did have 'O2 sensor aging' codes. Replaced the sensors and the car has been fine since.
Did you plug in a scanner to read any codes (pending or actual)?
My car has done this a few times and I am wondering what it could be?
I have changed the plugs and the MAF. I was planning on changing the front o2 sensors in the near future.I don't have any codes but I'm wondering if the o2 sensors can be less efficient but still not have any codes. When should they be changed(o2 sensors)? Did you see better MPG after you changed your 2 front o2 sensors? Thanks.
My car has done this a few times and I am wondering what it could be?
I have changed the plugs and the MAF. I was planning on changing the front o2 sensors in the near future.I don't have any codes but I'm wondering if the o2 sensors can be less efficient but still not have any codes. When should they be changed(o2 sensors)? Did you see better MPG after you changed your 2 front o2 sensors? Thanks.
As O2 sensors age, they slowly lose the ability to respond rapidly. When this happens, at some point you get the 'aging O2 sensor' code, and you will generally notice some stumbling/stalling as the sensor fails to provide the engine with the required signal. As ohlord stated, they are a replacement item at a certain mileage - you don't necessarily have to wait for them to throw a code.
I didn't notice a significant increase in my mileage, though the car runs very smoothly now and the engine hasn't even hiccuped since they were replaced.
I am close to 100K KM presently on my car. I am the second owner of this car.The previous owner did much of his milage in the city,and I am wondering if the o2 sensors being driven in the city need to be changed earlier than with highway milage?Did you buy your o2 sensors at the dealer? Where is the best place to get them? Thank-You.
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