: 94 Eldorado 4.6 High Idle



TN Torando
02-07-09, 12:30 PM
94 Eld Northstar, changed several parts including ISC, MAP, TPS, plugs, wires and so on heres also cleaned the TB, checked for air leaks also the problem at temperature or startup it idles around 750-850 and never drops down, heres the catch is i retract the ISC all the way and unhook it, let the car run for a while it will drop the idle down and stall but it sounds like there is something opening or closing when it does this any suggestions? No codes being given, would and EGR valve cause this?

Ranger
02-07-09, 02:24 PM
There should be no EGR at idle. If the EGR valve was stuck open or probably even partially open it would cause the engine to stall, not fast idle.

When you have the plunger retracted, did you set the gap to .060 before plugging it back in?

Can't imagine what would be opening and closing.

Necrosan
02-07-09, 03:17 PM
750 doesn't sound like a "high idle" at all.
I think the absolute LOWEST my Eldo has idled at was 600 RPM.

billytheshoe
02-08-09, 12:13 PM
TPS,The symtom is TPS. The ISC would cause surging. Up-down-up-down idle. The TPS will be steady high idle. Maybe returning to normal after cooling the motor. An intermittant problem occuring after the unit is at operating temp.

firstimecaddi
02-08-09, 01:09 PM
The ISC would cause surging. Up-down-up-down idle.

That is interesting, I am experiencing this surging idle and was wondering what might be thye cause.

What is ISC?

Krashed989
02-08-09, 01:17 PM
ISC = Idle Speed Control motor

It's located right beneath the big cruise control servo at the throttle body.

firstimecaddi
02-08-09, 03:32 PM
@krashed what can I do to confirm that the ISC is shot/on the way out?

Krashed989
02-08-09, 06:33 PM
If it makes a ticking noise or ratchets when you turn the engine off, that's a good sign that it's dead or on its way out. Otherwise, there is a method of overriding it from the dashboard, but I forget what PCM override code it is.

firstimecaddi
02-08-09, 10:39 PM
so how should I go here. Junkyard or brand new. How critical is this part to the whole set up. Is this the kinda part that you can gamble on and use a junkyard replacement...

STSj90
02-09-09, 12:42 PM
so how should I go here. Junkyard or brand new. How critical is this part to the whole set up. Is this the kinda part that you can gamble on and use a junkyard replacement...



Come on man, Just get a new one...No junkyard parts.

I mean, Look at how often you have to replace it...Its the kind of part that doesnt need replaceing that often. So go with a new one. Thats my opinion.

Just make sure you do everything right when replacing it and everything should do OK.:thumbsup:

Oh, and you dont know if this is whats causing your problem do you?

Check your codes first. See what codes come up...

firstimecaddi
02-09-09, 01:12 PM
that is exactly why i asked if to go new or junkyard. There are no codes at present. Only the surging at idle and ratcheting noise after shut off. The surging happens when the car is at operating temp.

TN Torando
02-11-09, 09:13 PM
I would say its the ISC you might want to check your coils for the surging also. If it is the ISC it has to be adjusted according to the manual.

Krashed989
02-12-09, 12:34 AM
Only the surging at idle and ratcheting noise after shut off. The surging happens when the car is at operating temp.

Definitely ISC motor.... I'm probably going to change mine on presidents day (it's doing the same thing). I'll post pics. :).... And to adjust the idle speed, there is a procedure in the manual BUT the idle will automatically adjust itself after a few drives even without doing the procedure.

Krashed989
02-17-09, 10:50 PM
Definitely ISC motor.... I'm probably going to change mine on presidents day (it's doing the same thing). I'll post pics. :).... And to adjust the idle speed, there is a procedure in the manual BUT the idle will automatically adjust itself after a few drives even without doing the procedure.

I apologize for not getting back to you on this. 2 hours and 30 minutes after I wrote that reply to you I was walking back to my car at the university campus. A group of 4 or 5 guys jumped me and robbed me. They took my backpack, which had my labtop, camera, and textbooks in it. They also stole my cell phone. Since then, the police have captured 2 of them and recovered my laptop, camera and phone but not my backpack or anything else that was in the backpack.... I am fine. The leader of the group blindsided me in the jaw. I was knocked out for a few seconds and nobody else hit me. All I have is a couple bruises.

I was surprised that I was knocked out by that punch though. I spar with my friends every now and then, and I've definitely been hit harder. I guess It's just a lot different when you're relaxed and really not expecting to get hit.

I still plan on doing the job on my car and I will probably do that next week sometime.

Tools you will need:
-flat-head screwdriver (for the hose clamps on the intake ducts)
-13mm (1/2inch) ratchet socket and ratchet (for the cross brace going over the air cleaner box)
-8mm combination wrench, gear wrench preferred (for the 3 nuts holding the ICM in place)

Krashed989
02-21-09, 08:22 PM
I finally got around to changing my ISC motor today. It was a lot harder than I was expecting.

Tools I used:
-flat-head screwdriver (for the hose clamps on the intake ducts)
-13mm (1/2inch) ratchet socket and ratchet (for the cross brace going over the air cleaner box)
-8mm combination wrench, gear wrench preferred (for the 3 nuts holding the ICM in place)
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1467.jpg

First you have to locate where it is:
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1454.jpg
It's in there underneath the cruise control servo
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1455.jpg

This is the new (used - from my donor car) one I installed:
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1456.jpg

Now to dig to it:
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1457.jpg
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1458.jpg
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1459.jpg

2 of the nuts are easily accessed with the gear wrench. The 3rd, not so much. I had to use the combination wrench on that one.
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1460.jpg

It didnt want to come out the easy way either:
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1461.jpg

Now that all of that is out of the way I could go and install the new one:
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1462.jpg

I had to prop the throttle open so I could get the nuts started easier:
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1464.jpg

But I got her tightened down and ready for action:
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1465.jpg

Then I put everything back together and started the engine:
http://i29.photobucket.com/albums/c296/Krashed989/ISC%20motor/100_1466.jpg

One of the toughest parts about this job is not dropping the nuts into the abyss in between the engine and tranny. I actually dropped my combination wrench into that abyss and it took me over an hour to recover it.

When I started the engine the idle was a little fast at 1k rpms, I revved the engine a couple times and it came down to about 800. I turned the key off and waited a few seconds before restarting the engine. It returned to about 800 rpms I revved the engine a couple more times and put the shifter through all the gears before turning it off again and restarting it. Then I took it for a drive around town and came back. The idle was about 650 rpms when I turned it off again.

Submariner409
02-21-09, 08:33 PM
Not good that you were mugged. Hope they hang the bastards. Glad you're (relatively) OK.

Very good work on the post for the IAC. Needs a reference bookmark.