4100 HT Idle speed setting
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 6 of 6
Like Tree4Likes
  • 2 Post By nizki1981
  • 4 Post By carnut
  • 2 Post By carnut
HT4100 4.1, 4.5, 4.9 Discussion, 4100 HT Idle speed setting in Cadillac Engine Technical Discussion; HI I have a 83 Eldorado 4100 HT. With your help ( guys from this forum) I've manage to tune ...
  1. #1
    nizki1981 is offline Cadillac Owners Member
    Automobile(s): 1983 Eldorado ht4100
    Join Date
    Sep 2011
    Location
    Mezica, Slovenia
    Age
    33
    Posts
    19

    4100 HT Idle speed setting

    HI
    I have a 83 Eldorado 4100 HT. With your help ( guys from this forum) I've manage to tune my car almost perfect. So thank for help so far.

    Now I have another problem. I'm trying to set the idle speed on my car. I have few problems with that. Now my ISC motor is fully extended and the setting screw is fully retracted. When engine is hot car idles at around 1000 rpm.. too much I know.
    I have tried to set the idle speed according to manual but I didn't mange it.
    I have warmed up the car, turned off all electrical users and AC, and checked the timing ( is set to 12 degrees, I,m running on 95 octane fuel (EUROPE)). Only thing I didn't do according to manual is ground the green test connector near alternator (I didn't find it). Then I have unplugged connector from ISC and retracted the motor completely connecting pins C and D to the battery. Then I've managed to set the Idle speed (with unscrewing screw at ISC) to approx 550 rpm (according to manual). I've turned off the engine (ignition to off) for 10 second. When I started the car it idles normal at 550 rpm, but when i reconnect the ISC motor to the connector it extends again completely.

    What am I doing wrong, why computer always extends motor completely, how can I convince car to idle at correct rpm....?????
    Please help.

    Thanks

    Best regards,

    Luka
    antboogie and antboogie like this.

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    66
    Posts
    5,733

    Re: 4100 HT Idle speed setting

    With the engine to normal temperature and climate controls off, open the throttle arm on the throttle body slightly with one hand and with the other press forcefully on the ISC shaft and hold that pressure till it fully retracts, then quickly disconnect the ISC wiring connector. Let the engine come back to idle. Now verify its idling at about 450 to 500 RPM WITHOUT the ISC shaft touching the throttle arm at all. The base idle is adjusted with the throttle stop screw on the base of the throttle body. Now adjust the gap from the ISC shaft to the throttle arm to approx. .060 inch. (60 thousands of an inch) Shut car off, reconnect the ISC connector. Count to 10 and restart the engine. Engage the climate controls in any mode after ECON. Assuming the A/C compressor engages, watch the ISC shaft. It should extend slightly just a milli second before the compressor engages. If it does not move, it needs replaced. And if replaced, it must be adjusted as mentioned above.

  4. #3
    drewsdeville's Avatar
    drewsdeville is offline Cadillac Owners Master
    Automobile(s): none
    Join Date
    Oct 2004
    Location
    WI
    Posts
    5,300

    Re: 4100 HT Idle speed setting

    Take it easy pressing on the plunger - "forcefully" can be misleading. All you need to do is close the throttle switch. It takes little/no effort.

    Remember, just about the entire ISC is plastic, inside and out...

  5. #4
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    66
    Posts
    5,733

    Re: 4100 HT Idle speed setting

    I guess a better word would be firmly. The main thing is to continue to press until it fully retracts and quickly remove the wiring connector. The manual says if the connector is left connected and the shaft is retracted, damage to the "driver" within the ECM can happen.

  6. #5
    nizki1981 is offline Cadillac Owners Member
    Automobile(s): 1983 Eldorado ht4100
    Join Date
    Sep 2011
    Location
    Mezica, Slovenia
    Age
    33
    Posts
    19

    Re: 4100 HT Idle speed setting

    Thanks guys for the advice. I've done everything correct and now I've found out that my TPS is playing funny. In closed throttle circuit it has value 13 on ECM and according to manuals it should have 0. Now I must first try to set or replace TPS and then I thing everything will be OK, because whenever system was in closed throttle circuit the ISC wouldn't retract, but when I've touched throttle just a little bit it retracted for a small fragment and so on.... So if I was pressing throttle continuously ISC retracted. Tomorrow I'll try to set TPS and see how it goes...

    Thanks for the advices.

  7. #6
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    66
    Posts
    5,733

    Re: 4100 HT Idle speed setting

    That's what I said, open the throttle then press until the ISC fully retracted. The 0 setting is done with the ISC fully retracted and a gap of .060 and the base idle speed must be at or below 500 RPM.
    antboogie and antboogie like this.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting