1979-1993 & 94 Conv [Subscribe to Daily Digest] |
First, a reading of a disconnected O2 sensor is of little value. That the car passes 'running' HC and everything else, it has to be an idle setting. Make sure that the idle switch on the throttle is functional (see the Saabnet FI FAQ as there is a ton of good information here). If the car will idle properly at 900rpm +/-50 (steady speed), the vacuum leaks are at a minimum and are compensated for by the AIC. If it labors to hold 900rpm and fluctuates up and down, there is still a vacuum leak or you have a bad AMM.
I doubt that the problem is in the HVAC selector, but it is possible. Do you hear a hiss at idle and a menacing hiss at boost? If so, there is probably a bad check valve on the vacuum reservoir in the RH fender and you have blown off a HVAC hose. Does the deflector flap change position when under throttle (the recirc flap for example)? This is also indicative of a blown check valve. The 'built in' one can be replaced with a 'pcv' check valve in the line.
I am sure that you are tired of taking it in for inspection. Adjustment of the mixture adjustment screw may be of help in getting it in spec. The 380 ohm setting is a start point. Tom T has a page on setting this. I would set this with a careful look at the o2 reading while it is connected to the LH computer. It is hard to determine an 'average' but that is what needs to be done. Before this is done, make sure the idle is smooth and that the o2 sensor heater works. Just as a check, check with the dvm to see what the ground potential is at the o2 sensor body to the battery negative terminal. Also check this potential to the AMM ground at the AMM connector. (the pin number is on the LH FAQ). Check the O2 sensor IN CIRCUIT at startup. It should have 0.6V on the lead at start and then it should start to fluctuate as the O2 heater element heats up. If not, the o2 is dead or there is no voltage to the heater. If the heater does not function, the system will function in 'closed loop' mode when the exhaust gas is hot (2500rpm), but not when it is cool (idle). Make sure this is working.
hope this helps
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