My '89 EA82T started idleing about 1k rpm higher than it should have couple of weeks ago. About 2300 when cold and about 1700 when warm.

 

I bought new wires, plugs, accel coil.

When putting the wires on I noticed that the AC unit was especially hot. The only thing I have replaced so far are the wires. Started it up and still high. Unplugged the AC wires at the compressor and no change in idle. I put the fan speed to 1 and then hit the off button for the vents. Idle went to about 1100. Hit any of the buttons and up it goes to about 1700. I removed the fuse inside the engine compartment and it does the same thing.

 

Conclusion: A signal is getting sent to the ECU making it think that the AC is on generating a load so it ups the idle.

Any other thoughts as to the cause?

 

How do I fix it?

 

Thanks,

Jay

did you check the idleing screw is by the carb or injectors whitch ever you have. its usualy a philips screw driver.

Poss.a vacume signal problem? The heater controlls are all vacume:eh:

Just a thought there. I'm not sure where the computer takes it's signal from to up the idle.

Jay, I believe you are on the right track with the AC connection. One small item, I believe this portion dealing with the FICD (Fast Idle Control Devise) on a turbo car is independant of the ECU. It is under control of the AC system only.

I think the micro switch for AC control is either stuck closed or jamed in some way to keep it in the closed position.

To check this micro switch look above the throttle pedal and in toward the HIVAC housing. There will be a black sheathed set of two blue wires. This runs to the control microswitch under a cover.

The other end terminates in a plug, you could disconnect it there for testing purposes.

If you feel this information is some help but can not locate the switch please feel free to email me.

I have pictures of said location.

I rewire this micro switch switch to a control switch beside the blower control. Yielding AC in any vent position.

I disconnected the small plug that Skip mentions (great pic btw) and it is working the same. Meaning that the disconnect didn't help.

 

I have disconnected the small plug to the micro-switch, yanked the AC fuse, disconnected the two plugs by the compressor.

 

I still have high idle unless the dash vents are Off.

 

More thoughts??

 

Thanks,

Jay

Glad the pict help find the plug, sorry it didn't cure the problem. If you emailed back, it got "spammed"

There are two relays behind the pass strut under a cover.

The feed for the AAV is suppose to come off of the AC relay (beside it is the rad fad relay for turning on the rad fan when the AC is on.)

You could try unplugging the AC relay to see if it fixes the problem.

I disconnected the outboard plug near the AC fuse under the hood. The idle returned to normal. Now I just have to figure out what is wrong before the hot weather returns in 5 months.

 

Thanks for all of the info Skip.

 

Jay

check the throttle cable..

My car started doin that and it was the cable was sticking

wasnt returning to low idle