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CIS warm-up RPM
Have an 81'SC that during warm-up, RPM seems too low. It takes a good 5 minutes for the RPM to stabilize at 1000. after full warm-up, everything is good. My question is: what should be the normal warm-up RPM? and for how long. Am in Sacramento and outside temp is hot during start up; 80 degrees+ any ideas? Aux air regulator or thermo-time switch?
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09-15-2000, 07:38 PM
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It's not the thermotime switch. That's only used to turn on the starter injector during engine starting. The two components that are "active" during warm up are the aux air regulator and the warm up regulator. The aux air regulator provides air that bypasses the throttle valve. This is to increase RPM during warm up. The warm up regulator acts to increase fuel richness during warmup. If your idle is low, but smooth, I would first test that the aux air regulator is working. There have been many threads posted about how to test its operation.
------------------ Bill Krause '79 911SC Euro |
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09-16-2000, 07:44 AM
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should the aux regulator disc be FULLY open when engine is cold? even when outside temp is relativly high? 85 degrees F? IF the disc is not fully open, will the fast idle RPM be lower? Any ideas?
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09-16-2000, 12:01 PM
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There have been some other threads on this topic. From what I've read here, the aux air valve won't start to open much until below 50 or 60 degrees F. I haven't been able to locate any more accurate numbers than that.
------------------ Bill Krause '79 911SC Euro |
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09-16-2000, 01:22 PM
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My '76 911S has almost the exact opposite symptoms. Instead of low RPM at cold startup (now this all the time, 85 degree weather included) I have high high idle, usually at around 1800-2000rpm. The WUR is a rebuilt unit changed about 500 miles ago. Which aux. air regulator would I have to check, the left one with tubes coming out of it or the right one with the electrical plug into it? Thanks!
------------------ Jeff 1976 911S |
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09-16-2000, 03:59 PM
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The one with the electrical plug would be the one I'd check first. Inside of it is a heater element that heats up a bimetal spring which causes the valve to close up. If the heater element is burnt out, the valve won't close. If you have an ohm meter, you can measure the resistance accross the contacts on the valve to see if it is open. Also you should check the voltage on the connector to see if the valve is getting any voltage. Voltage should only be present when the engine is running.
------------------ Bill Krause '79 911SC Euro |
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09-16-2000, 04:33 PM
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