Lambda Check

Benzmac: I found your Lambda article in the tech archive most interesting. I watched a tech do this at a club technical session a few years ago and he set the lambda by using only the voltage reading. For those of us with a simple digital voltmeter, is there a way to do this properly. My foggy memory seems to indicate that he used something around 3.5 volts. Part 2 of the question is that if it is possible to do this, is the reading altitude sensitive? ie: is the setting the same at sea level as, say, 8000'?

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'88 300CE, 52,000 mi

[Benzmac]

I don't know if you set it differntly for altitude, I am at 1000 feet above.

I use the outline as stated for measuring purposes. I have never heard of checking it with voltage??

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Benzmac:
Donnie Drummonds
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ASE CERTIFIED MASTER AUTO TECHNICIAN
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[barrie]

Yes, a simple voltage test (Bosch recommended) is used to check the O2 sensor element. This test will identify the most common cause of sensor failure. However, there are two other system functions that should also be tested: a current-draw measurement on the heater, and a duty-cycle measurement to test active operation. Alternatively, you could use an oscilloscope-based procedure (with propane) to test all functions.

If you're interested in DIY, I've outlined these tests in an earlier post (Search 'O2 Sensor' and 'Barrie'.

With respect to your second question, I wouldn't worry about altitude as this is a relatively crude device. In other words, if it passes these tests you're fine, otherwise 'replace'.

Hope this helps!