I submit the oxygen sensor had nothing whatever to do with the high revs.

But I must ask how the throttle got stuck open. And to guess how much it was open I'd want to know if this was an automatic in drive, or a stick in neutral, or what -- meaning what sort of load did the motor have when the rpms where high.

Same sort of questions arose when the Toyota Syndrome was popular.


--
Art Benstein near Baltimore

How many times is it appropriate to say "What?" before you just nod and smile because you still didn't hear what they said?

A) What you described should not happen but it did.

B) The O2 sensor is the third or fourth most important component in a semi-modern fuel injection loop like we have in Bosch LH2.4 systems. It works like this:

To start the car, the only important component outside the ECU is temperature sensor...this determines which start-up map is to be used.

Started, idling, but not up to operating temp (engine or O2 sensor) the MAF/AMM/MAP sensor and the whatever is used as a tach signal (crank position sensor) are primary with the TPS having the minor roll of signally the idle map.

Started, driving, but not warmed up is basically the same but a preset map for "normal" driving.

Started, driving, warmed up...this is where it gets fun. AMM helps the ECU guess the amount of fuel needed and O2 sensor gives feedback of how accurate the guess was...these two sensors continuously adjust the mixture.

So if the O2 sensor is massively out of range for what the AMM guessed should be happening, a code should have popped and limp home mode initiated. As the lack of exhaust flow across the O2 sensor, and exposure to fresh air, should have maxed out the lean reading (too much unburned oxygen) it would have dumped a lot of fuel for couple seconds (or less) but then the fault should have popped a code and put you in limp home.

the o2 sensor is integral and crucial for proper engine management. i saw a sedan a few years back which ran like crap for at least 2 years before i saw it and diagnosed a broken o2 sensor wire connection under the fireproof sheath. after simply splicing the 3 sensor wires ( not even changing the sensor mind you) the car idled and ran perfectly as if by magic.