High Idle in neutral

[krs09]

This seems a little weird. After a lot of tweaking with the idle and finally thinking I was close to moving on other issues a little something new popped up. I took the D went out for its first real drive in 20yrs and considering, it went very well. What was weird is the idle was great when the engine was cold (hunted for 10sec and was fine) but after about 25min of driving the idle sounded very high at stops (tach is broken so not sure how high) but when putting the car in gear the idle dropped big time and sounded beautiful but as soon as you held in the clutch the idle would scream! What gives??

Fun Fact : I do have the Idle speed thermistor jumped behind the driver seat. When we first put the engine in the idle was very high and was told to jump the switch to bring the idle down on start up and so far so good but now I think when the temp gets hot that jumping of the switch may be interfering with the idle speed. Would that have anything to do with it?

[DMCMW Dave]

When you get the high idle like that, turn the engine off. Wait a few seconds and restart it WITHOUT touching the gas pedal. What happens?

Second test - with your finger, or a screwdriver, manually press the throttle arm closed (on top of the engine). Does this do anything?

[krs09]

When you get the high idle like that, turn the engine off. Wait a few seconds and restart it WITHOUT touching the gas pedal. What happens?

Second test - with your finger, or a screwdriver, manually press the throttle arm closed (on top of the engine). Does this do anything?

I'm on it. Thanks Dave

[krs09]

So this high idle thing has been killing me. When slowly letting off the gas the engine would run loud but if I tapped the gas and let off quickly it would come down a bit. It turns out (as of now) the throttle arm was not returning to fully closed position, when running loud I would press the arm closed and ta-da back to normal. After further inspection the arm that connects the throttle spool to the butterfly plate was too long so when fully returned the arm would keep the butterfly plate open, simply adjusting the arm (making it a little shorter) fixed the issue. Now the veh idles lower and runs cleaner then it has so far. I think this has been a issue for quite a while now. Thanks Dave for the tip!

[Elvis]

For sure you have the shaft/bearing problem when vacuum is applied.

It's been described here around 10 times or more.

[DeLorean03]

It's been described here around 10 times or more.

I'd love to see all 10 times if you're keeping track.

[krs09]

For sure you have the shaft/bearing problem when vacuum is applied.

It's been described here around 10 times or more.

???:hmm:???

[Jonathan]

It's been described here around 10 times or more.

Thanks for letting us know, Bill.

[David T]

Thanks for letting us know, Bill.

Since you say the car has not been used in many years I would clean and relubricate the throttle linkage starting with lubricating the throttle cable as per the recall. Also take the throttle spool apart and do that too. The grease gets old and sticky and makes it hard to return all the way to idle. Make sure the carpet or a floor mat is not interfering with the cable.

[Jonathan]

David... on a side note... you do realize there is a "Reply to thread" button as well as a "Reply with quote" one, right?

[David T]

Now you are asking me to get fancy with all of this modern technology? Sometimes I hit reply and sometimes I hit reply with quote. Is it that important? I must admit I am not using a smart phone, I like to type on a keyboard.

[Jonathan]

Nah, no need to get fancy :) I just thought you might not have realized the function of each of those. And only because sometimes the last comment in a thread you quote isn't relevant to the comments you've made in your post (which often is back to the OP and not whoever last chimed in before you).