"...my main concern is why there is no change in the reading when i pull the vaccum to the fpr and also when i cause a vaccum leake in the system.thanks"

• OK then. I did notice that your voltage readings match what's specified for the Titania sensor.

But I question that vacuum test. Sure it causes an air leak, but also lets the FPR "see" atmospheric pressure, as with Wide Open Throttle—so it raises the fuel pressure about 9 psi, which tends to richen the mixture.

I don't know if that rise in pressure is enough to offset the induced vacuum leak. But if that test is from the same source that thought you could test the 02 heater with the engine off, it's grain of salt time.

As long as your 02 is switching rapidly between thos voltage levels, I'd say it's doing the job.

It's possible to "force" stronger rich and lean signals to the ECU, and watch the (unplugged) sensor to see if it responds accordingly. Post back if you want my canned blurb on that.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.