I am using Direct Scan for the first time, I had warmed up the engine and recorded what happened while revving the engine at ~2500RPM. The O2 sensor stopped bouncing around for about 5 seconds and hovered at 100 mV. During this time the INTegrator stopped moving and stayed at 128 while the BLM stayed constant at 111. It was in closed loop the whole time and the LEARN flag was lit. It seemed to be running as if in open loop. Right after this everything started working fine again.
Odd behaviour recorded by Direct Scan
- Thread starter BJM
- Start date
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You may have triggered the ECM into either PE(power enrichment) or AE(acceleration enrichment) for that brief few seconds. Anytime PE or AE is engaged, the the INT and BLM are locked, even though the learn flag is active, it wasn't being used under those conditions.
When I blip the throttle I saw the AE light go on, I checked my file and the PE light was never on. I was holding the revs steady at a really high idle. Also the O2 sensor was really low, it was perfectly stable for the few seconds as if in open loop. Are there conditions where its actually in open loop but the closed loop flag stays on?
The code is written for the normal or about normal operation of a car. You can generate odd circumstances from time to time, and beat the normal parameters.
PE is a *special* case. It can use some of the info learned in closed loop but since it's not actively using the O2, it's truely in open loop.
Having the closed loop flag lit does not mean that the ecm is in closed loop. It means that the tests for minimum run time, coolant temp, and O2 sensor activity have been passed and so it's okay to go into closed loop if it's not in PE or other transient modes. My guess is that you revved it up then lifted off the gas and went into DE or DFCO mode (decel eleanment or decel fuel cutoff), which would drive the O2's down to the levels you saw but should have also lit the appropriate flags. I don't remember if the learn flag stays on in those or not (it's still BDC - before diet coke; too early in the morning 
).
).Then the only other thing I can think of is that the O2 sensor might not be quite hot enough (or some other oddity) because of the "no load" condition you're subjecting it to.
2500 rpm with no load is a very unusual circumstance anyway, and you may very well see some wierd things.
