just replaced the o2 sensor on my 86 300e with a bosch #13953, soldered the wires shrink tube a nice clean job, now its ruffer than before and surges when I accelerate, whats up

tried disconnecting battery for a little bit runs smooth now no surge or ruff idle

Can someone explain what happened there? Seriously. Is there an actual reason this would happen?

Wondering, because I just replaced mine with the exact same thing. Mine runs fine. Just wondering why it would happen with one but not the other.

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1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
105k miles

1989 Mustang GT Cobra Convertible
43k miles

this usually works on american cars to clear a check engine light so I tried it just as a starting point

I can understand that for clearing the CE light. I don't understand why it would run differently.

How did it run previously? How does it run now if you unplug the single connector?

Unless I am mistaken, it shouldn't affect anything anyway until the engine is warm/hot.

__________________
1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
105k miles

1989 Mustang GT Cobra Convertible
43k miles

that was the first thing I triedafter the first trip around the block, let it cool off disconnected for about 15 min. reconnected drove around, the idle before was around 700 now about 600 a little smoother and accels about the same, changed the o2 to see if milage would get better

pLEASE, hOW To know that the 02 sensor doesnt work right?

or How to test the O2 sensor? Have the O2 sensor some caracterists value as electrical ressitance etc.?

Thanks.


MARIO FARIAS
laprefar@cantv.net

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MB LOVER

bad milage and a ruff idle was my indicator

Mario,

What kind of test equipment do you have?

There are two types of O2 sensors commonly used: Zirconia and Titania. Zirconia can be identified as having flutes on the end. Titania has an exposed flat element on its end. Both types can be bench-tested using a propane torch and multimeter.

ZIRCONIA

1. Set voltmeter on two-volt scale.
2. Connect positive to sensor lead; negative to sensor housing.
3. Hold sensor with pliers, heat with propane torch and record voltage. A good sensor must be able to produce 0.8 volt or higher within 60 seconds.
4. Next, remove sensor from heat source while observing voltmeter. Voltage should drop within 3 seconds.
A sensor contaminated with silicon, lead, burnt oil, or antifreeze will not pass this part of the test.
To test the sensor's heater, connect the leads to an ohmmeter. Any ohm reading is okay as long as it's not an open circuit.

TITANIA

1. Connect black and gray sensor leads to an ohmmeter set to roughly midscale (200K).
2. Hold sensor with pliers, heat with propane torch and observe ohmmeter indicator. After a few seconds, the ohmmeter should indicate an ohmic value. This reading will vary with flame temperature.
3. After observing reading, remove sensor from heat. The ohmmeter should register infinity.

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95 E320 Cabriolet, 159K

hey Kestas,

I am curious as to what you are testing for by heating an O2 sensor?

What are your references/documentation to validate this test as being applicable to O2 sensors?Are they manufacturer? ASE?

Just wondering.

O2 sensors are mini power generators. They develop voltage at high heat depending on the amount of oxygen present.

The information I posted is transcribed nearly verbatim from a Wells book on testing sensors in a computer controlled vehicle. The book was written at least ten years ago and has a lot practical information for the DIYer.

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95 E320 Cabriolet, 159K

Thank you Kestas

Hi Kestas,

Great information on the testing of O2 sensors. I believe that is my challenge with my car at this moment.

I was wondering if you know where I might be able to find the information on how to find the suitable replacement O2 sensors. I read some threads about using NGK/NTK sensors that are for other cars like Ford. Any thoughts. I have a '97 S420 M119 engine. I could not find anything in the search that would help me.

Thanks,

Tom

Further research has determined that this ( Ketsas) method will check for voltage only, but a vehicle O2 sensor must not only generate voltage, it must generate voltage swings from neg to pos. in a specific time frame measured in milliseconds.

One might consider manufacturers methods to check O2 sensor in the vehicle for a more accurate diagnosis.