DMM freq & O2 sensor cross counts?

No.

In message , Lance Morgan writes

Probably not, a lambda sensor switches (usually) a couple of times a second, you need a pulse counter.

It seems a minimum of 3-10 Hz is specified for Zr type sensors.

Does the freq feature only work if a OV baseline is involved?

As a possible alternative? to a bench o-scope, a DSO, a high-tech hand-held scope, or an A/F meter, it would be interesting to see what the O2 sensor(s) is reporting (Max/Min/Avg/Hz) while driving, when a fuel related driveability problem is actually occurring (running DMM test leads from sensor into cabin)

Thank you

It seems that you'd like to have a data logger instead of a meter. Time stamped data might be what you want. I'd suggest something from either James Electronics or JDR... those are two places that I think might have them... no guarantee that they are the best prices...

Harvey

Use a 'scope. On a hot O2S, the switching time ("rise time, fall time" if you're into EE) on a high speed idling engine for a zirconium dioxide oxygen sensor should be under 100 milliseconds. If the sensor's output lead's close to the ignition system, you may notice hash on it (e.g., on my 1995 Ciera with 3.1 liters engine, there's plenty of hash -- scan tool intermittently shows cross-counts of 255 -- this occurs only when O2S output voltage > 450 mV).

If switching time's greater than 100 mS, raise the engine rpm. If it's still greater than 100 mS, replace the oxygen sensor.

Oscilloscope type doesn't matter. I originally used a 25 MHz dual channel Heathkit analog scope; now it's a Tektronix THM465 "etch-a-sketch" DSO (both are obsolete). You don't need anything that's high bandwidth (this isn't Schottky TTL or ECL circuitry you're troubleshooting or designing).

Regards,

Bohdan Bodnar

Lance Morgan wrote: