I just returned from a 2200 mile NM, CO trip. I had lots of windshield time to stare at my gauges, etc.
I noticed something interesting going on on the UltraGauge.

When I step down to accelerate and pass someone (at low altitude) the UltraGauge will show the engine going into Open Loop. I was monitoring the Temp and O2 sensors, and didn't see anything too out of the ordinary. Temp stays consistent. I'm not exactly sure what I am looking at when I see the O2 banks numbers though.

Another observation. When climbing through steep terrain in Low Range, 1st gear at high altitude. IE: greater then 5000 feet, upwards of 12,500ft (Engineer and Imogene Pass') the engine would go stay in Closed Loop, but temps would rise significantly. The second I would turn around and begin the decent back down the mountain, and let the engine do the braking. That would be Low Range, 1st gear, the engine would go to Open Loop and temps would fall by 20+ degrees. As soon as I would tap on the gas pedal, it would Close loop again.

Am I looking at bad O2s? Bad Temperature sensor? Normal operations?

I'm just trying to determine what would cause it to go from Open/Close loop so much and often.

Thanks.

 

Normal. Mine drops out of close loop when wide open throttle. As for mountain roads near me, a bag of kitty litter has more elevation....

 

Thanks Buzz.
Do you have an idea what "normal" readings should be on the UltraGauge for O2s?
What about MAF on the Gauge? I see numbers, but they don't mean anything to me.

 

The Fed considers full throttle a emergency situation, no emission control. Can run full rich if it needs to. That's why catalytic converters burn up on people who hot rod there cars a lot.

 

Normal operation. On engine braking the control unit goes open loop because the computer wants to regulate idle speed and cant get the engine down to the target RPM. If you were to roll down the hill until the engine idled it would have gone back to closed loop. Narrow band oxygen sensors cant react fast enough for the computer to do real time fuel adjustments, so when you mash the gas It uses the airflow/throttle position/engine speed + base map to calculate fueling and ignores the o2 sensors.

 

Awesome info! Thank you...
Any idea what the UltraGauge should read for "normal" O2 readings?

 

If I recall correctly from the RAVE, normal O2 ranges are +/- 5%, both short term and long term. Mine go outside that briefly and occasionally, but are mostly within that range. I'm no expert but I think an O2 reading outside that range for an extended period throws a code.

 

The Bosch ECU manual in downloads below give ranges of values that have to be exceeded for certain codes to be generated.

 

Engine temps always rise when you are working the engine, i.e. climbing a steep hill.
Going down the hill the engine is not working, its coasting.
Normal O2 readings will be anywhere from .05v to 1.0v and the numbers will vary rapidly.
Slow volt changes means a dying O2.

 

So what will be the normal reading while idle? Do they keep the same steady reading? Mines go from .20's to .80s constantly.