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Old 10-28-2011, 02:12 PM
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Join Date: Oct 2001
Posts: 226
Oxygen Sensor Voltage

Using a Snapon Mt2500 Scanner, I activate the secondary air pump in closed loop. Is the voltage supposed to drop to 40mV and stay there? My results are not consistent. Voltage before the activation can be anywhere from 150 to 4-500 mv. The first activation seems to drop the voltage the most but may hit the 40 mV only momentarily before bouncing back up to 150 -200 and stays there. Is the ecu compensating for the lean condition. When attempted again (maybe a minute later) the drop is never that much and does not approach the 40mv. Any ideas what is going on? The pre-cat O2 sensor is OEM and was replaced not long ago.
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Old 10-31-2011, 09:35 AM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
Air volume to the O2 sensor is the key to code P0 410.

How much air does the pump out?
Does the diverter valve hold vacuum & open completely?
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Old 10-31-2011, 11:52 AM
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Join Date: Oct 2001
Posts: 226

To test, I've disconnected the rubber tube connecting the divertor valve and the pump is blowing a lot of air when activated (like a hair dryer). Vacuum is being supplied by the actuator to open the divertor valve when the fan is on. And the divertor valve opens fine when applying vacuum and allows air through. Yesterday, poured in some Seafoam through the divertor and actuated the fan to blow into the air passages. Ran car, lots of smoke from the Seafoam through the exhaust. Actuating the air now, the O2 registers a low voltage (30-40) and rises to only 100-120 mv w/o the air. Not sure if that is due to residual Seafoam causing the low voltage and causing a false reading. However, after driving the car approx 10 miles in 20 minutes, got an ABS light and limp mode. Restarted car, still in limp mode. Checked with scanner and got the following codes:

022 cc/ea actuator reports limp-home mode
071 tn speed signal output short to pos.

Do you know what these mean. Will clearing the codes remove the limp mode, at least until it sees another limp mode worthy condition.
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Old 10-31-2011, 02:29 PM
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Join Date: Oct 2001
Posts: 226
By the way, you mention the P0410 code. I've never had this code.

I know this is jumbling everything together, but one thing since the ea/isc is indicated somehow with the limp mode, in other posts I've mentioned that at a stop with the a/c on, when the compressor kicks in, the engines drops rpms and stumbles for a second before recovering. Never has stalled. Looking at JimF's site, I see that the EA/CC/ISC is reponsibile for the following:

"When the A/C compressor is turned on, the throttle valve opening is increased just before the A/C compressor engages. This compensates for the A/C compressor load and keeps the engine idle speed at a nearly constant RPM."

Is my car's throttle valve opening NOT being increased just before the A/C compressor engages? Pointing to an issue with the EA/CC/ISC?

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