My 1986 4x4 does not like to idle at a constant RPM. It will run at 1,200, then drop to 1,000 and speed back up to 1,200 about once/second. I need to get it through DEQ within the next two weeks. I know that's a high idle speed, but it was set that way so that the A/C would come on. Any lower and the compressor would not engage. I'm in Tucson!
Any idea where to look for a surging idle problem like this?
Thanks,
Glen snipped-for-privacy@ccim.net
Turn down the A/C amplifier cutoff RPM, look behond the glove box for a small black box with a knob labelled "RPM". That's what determines whether the A/C compressor should cut out or not.
Turn the idle speed down, 1100 is where the ECU starts cutting fuel when it sees the throttle closed and the RPMs too high.
Or adjust the A/C idle up valve to kick the idle speed up while the A/C is on. Its the white knob atop the intake with the vacuum hoses connected to it. Its job is to boost the engine idle RPM while the compressor is running to keep from bogging down the engine and to ensure adequate RPM at the compressor to allow it to work properly.
You could also just turn down the idle for the DEQ test then turn it back up when the need for A/C arrises again.
small black box with a knob labelled "RPM". That's what determines whether the A/C compressor should cut out or not.
sees the throttle closed and the RPMs too high.
Roger's first answer solved the problem. It now idles at 750 rpm and the A/C compressor comes on as needed! Thanks a bunch, Roger!!
Glen
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