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Pierburg vacuum valve in PAIR system 900 1997

posted by larry139 on Fri Jul 30 07:13 CST 2004
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Many thanks to earlier responders to my PAIR questions

However, my problem is with the PAIR system, not evap system. Valve in question is on driver side and below cannister Purge valve. It has small plastic hose connection that runs over top front of engine to the air injection pump solenoid valve located on passenger side, with hose (approx. 1" diameter) to air injection pump. My Volvo parts buddy tells me this is the EGR (exhaust gas recirculating) valve. There is a small vacuum hose with a small check valve that connects to this "EGR" valve. Valve apparently is normally closed and is apparently actuated by signal voltage from ECU (?). When valve is bypassed by connecting inlet hose to outlet hose (to the air pump solenoid valve), the air pump runs OK. Question: Is it OK to connect 12 volts to valve connection as someone suggested? Voltage on input connector varies from about 200 MV to 700 MV with high sensitivity digital meter (Beckman).
I assume the exhaust O2 sensor signals the ECU when secondary air injection is needed. Maybe a 1.5 V test signal should be used. Any suggestions and/or comments greatly appreciated. Larry
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L R Hicks

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Pierburg vacuum valve in PAIR system 900 1997

posted by sped on Fri Jul 30 14:22 CST 2004
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Hi Larry, I had a similar problem, I kept on getting a code PO401 secondary air injection system. My valve on the exhaust side was bad causing exhaust gasses going through the little hose and messing up the solonoid valve and the check valve( this is on a 97, 960 ). I had a hard time believing how much the solonoid valve was and used one from a Chevy Tahoe I had laying around. So far so good. I am not sure though if the air injection system air pump runs from the signal of the "O2" sensor, since the system is in open loop upon start-up, I think there is a built in timer and relies on the temp. sender(all in the ECM) for length intervals. I could be wrong. Pauli

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