Car was driving fine last week Friday. Idle wasn't perfect as I've just recently got the car running and didn't spend any time fine tuning it. It idled at about 1100 once warm but it was a smooth consistent idle.

On Monday morning the idle was hunting on me. In some instances it would hunt between 1800 and 2200 and others would be 1300-1500. Then I noticed that it did this mainly when the clutch pedal was pressed in. Idle would roam a little bit but eventually settle around 1300 without pressing the clutch. As soon as the press the clutch in with trans in any gear the idle jumps up and begins hunting until the clutch is released.

I searched for forums and found issues related to the clutch switch. I removed mine and cleaned the contacts (spring was intact) but it had no change on the issue. I even jumped the connector together to ensure that it was a solid connection and it was the same.

Any ideas or direction from here? It has something to do with whatever mode the ecu jumps into with the clutch in.

 

There are 2 clutch switches, you may not have done the one the ECU sees. As well as making sure the spring isn't broken, make sure the rubber button it presses against on the clutch pedal arm hasn't disintegrated. If so, you can get rubber stick-on chair leg pads from the hardware store, they work great and last a very long time.

Dale

 

I think I did the right on. I did the one on top (under the dash) vs the one that is against the firewall. Also I closed the switch by hand and it made the idle roam as if the clutch was being pressed in.

I just finished removing and cleaning the ICV with carb cleaner, it had no effect. Impedance measured on it was a little high at 12.7 (range is 10.6-12.3, I think?). It was actuating with 12v across the terminals though.

 

Make sure the idle is adjusted correctly. To properly set idle, you need to warm the car up fully, jumper something at the diagnostic box, and adjust using the air bleed screw below the throttle. I wouldn't be surprised if the adjustment screw on the forward side of the throttle body was messed with. There is a white paint mark on it to ensure it hasn't been screwed with. Just make sure that it doesn't hold the throttle plates open and adjust with the lower screw and you should be ok.

Matt

 

I've got the forward screw turned to the point that it's not even in contact with the throttle cam. The air adjustment screw (under TB) can actually be tightened all the way and the engine still revs too high. You would think this would stall the car, right?

 

It could be your isc valve. Unplug it and see what happens to your idle. Mine is acting up but it stops doing the crazy bouncing idle when I unplug it. I think I am going to block it off and see if that helps.

 

IAC sticking, throttle cable too tight, dashpot sticking, throttle body physically sticking, TPS off, or one of the other adjustments is way off. The reason it hunts is the ecu is trying to drop the idle but it cant. Get the factory service manual and go through all the throttle body adjustments. Could also be a vacuum leak holding the idle that high.

 

Pretty sure switch on top under dash is the one for starting the car. The one against firewall is the one the ECU sees.

 

Fixed - It was a vacuum leak. I was pretty sure it wasn't since I had just redone them in Silicone and have checked them over 3 times in the last two months for other issues. Turns out the PCV line from the Oil fill neck to the UIM had somehow split and came off. I must have nicked it or something because the end of the line was all torn up.

Luckily when I was shining my light around I caught a glimpse of the loose end without having to remove the UIM.