fast and warm idle issue with new rebuilt carb

[lx 1986]

I posted a couple months back about my throttle cable. Thanks for responding. I did find one.

I had the carb changed and my mechanic said I needed another cable because the carb couldn't be adjusted correctly. I got all this done. He tried to adjust the carb because on a cold start the idle would go up to 2500rpms and then rise to 3000rpms and would go down to 2500rpms and then start to rise again to 3000rpms and never come down until you stepped on the gas and then it would drop to 700rpms.

Well I checked to see if he hooked up the hoses correctly. I found 2 were not. They were on the choke opener. I switched them and then adjusted the idle and ac screws. Now the problem is when I start the car in the morning it starts and the idle jumps up to 2500 rpms and then drops rapidly to zero and the car dies. If I step on the gas and make the car idle at 2500 rpms and wait until the car warms up then the fast idle holds at 2500 rpms and then starts to rise to 3000 rpms but never goes down until I step on the gas and then it drops to where it's suppose to idle in park or neutral because by then the car is real warm.

I'm also noticing a problem when the car is warmed up and I go somewhere. When I restart the car. The idle will sometimes hang above 1000 rpms and doesn't want to come down. Recently I found while adjusting the idle screw there is a sensor in the snorkle of the air cleaner housing with a electrical connector attached. When I disconnected the sensor the idle drops to normal. The dealers site calls it a air temperature sensor part# 37880-PH4-661. Could this be the problem with fast and warm idle issues?

I have 4 questions:

1. Is there a way to test the sensor?
2. Does the sensor turn it self off and on?
3. Is the sensor connector wire connected to any thing else other than the battery.
4. Would it ruin anything if I left it disconnected? (Idle doesn't hang above 1000rpms when car is warm and sensor is disconnected)

I would appreciate if someone could answer all of my questions.

86 Honda Accord LX, 2bbl Keihin carb, 4spd automatic with ac

Thanks

[g.frost]

Download the service manual available on this site. Get the '88 addendum and section 12 page 188 is a procedure to test the sensor. You will need a multi-meter. It is a thermistor sensor; it changes resistance with temperature. It is fed 5 volts from the control board. I'm not familiar with 'theory of operation' or how the computer uses this sensor reading.

If you want the computer to think the air temp is always warm, looks like a .5-1K resistor could be wired in it's place (air temp of 100-140F)

The 2500 idle issues are likely related to the vacuum lines on the choke opener and fast idle unloader: vac lines 18 and 19, and associated thermovalves.

[lx 1986]

I'll check out the sensor and vacuum lines. Thanks for the help. Much appreciated