Over the last couple of weeks I've been cleaning up and restoring my intake system including the throttle body, W pipe, and air meter unit. Basically went down to the valley and rebuilt from the bottom up. I have everything re-installed and now I have a high idle.
Symptoms include:
- No surging when cold anymore
- Idle is starting around 950 and creeping to 1200 by the time the fans come on
- If I unplug the idle speed motor plug, the engine doesn't die, in fact nothing happens. I thought the motor should die at idle if the plug is removed? This seems to suggest to me that the throttle isn't closed or there is a vacuum leak
- If I manually rev the engine by standing behind the car and turning either the throttle spool, or disconnecting the linkage and pulling back on the arm connected to the throttle, it doesn't always return to the idle speed it was previously at. Sometimes I have to press the arm into the throttle stop to get it to go that last millimeter. It seems like the butterfly plates are sort of hanging up? I have tried disconnecting the linkage to confirm it's not binding and it doesn't improve the situation.
One question I have is, should the butterfly plates close 100% so that they are perpendicular in the throttle? Mine are open a few degrees and if you try to turn them a bit further to perpendicular, it feels like it's binding somewhere (this is even if the arm and spring are removed from the throttle and I'm just turning the threaded end).
I have attempted three times to set the idle by backing out the stop screw and idle switch screw and just barely screwing it in until it hits the stop bracket but I'm not returning to that low 750 RPM like I used to. I'm just stuck at 1000 or greater, and sometimes when revving the engine it gets stuck even higher until I push on the throttle arm to get it to close that last millimeter because the spring on the throttle isn't quite strong enough.
I did a lot of cleaning with carb cleaner, etc in the throttle. The decel springs appear to be in good shape and I did confirm they are fully seated closed the last time I pulled the W-pipe off tonight. New o-rings on the W pipe and new white plastic spacers in front of them. New paper gaskets on the W-pipe and everything is confirmed tight. I have gone over all vacuum lines and vacuum leak areas and can't find anything however I haven't tried spraying starting fluid or anything around yet to see if it would get sucked in.
I guess first thing is to figure out why the Idle speed motor won't kill the engine when I unplug it, and if the butterfly plates are supposed to be truly perpendicular?