Page 2 of 32 FirstFirst 123412 ... LastLast
Results 11 to 20 of 320

Thread: E38 idle tuning

  1. #11
    Lifetime Member hymey's Avatar
    Join Date
    Jan 2008
    Posts
    299

    Default

    Thanks Simon,

    I had to give you a call on this to get you logging as you always come up with good results.

    Since speaking to you I changed max idle area as I wrote in my post above. Lowering this prevents the idle "sticking" I will post a link soon of it idling with tables zeroed. It was sticking or hanging but no problems once tables were lowered. What is very interesting is the proportional and integral controls as reading the science behind these show proportional is a direct change and integral a sum of those changes but in this case it is ass about. Mine is idling at 7% and has no hunting at all with minimal timing correction, Now I have found correct airflow I will increase max idle area to standard setting and zero proportional control then using integral to correct minor changes.

    Ringram would be good to see how your car goes with some idle tuning testing(save ur good tune lol) . Initially I had a few troubles with idle airflow and reducing proportional control helps a lot. Min idle airflow is nothing more than a minimum commanded TP% with max idle area being the above ceiling everything else in between is learnt and correct via airflow correction tables and spark control. Zeroing the tables and changing the other tables is how I was able to find correct airflow,
    Last edited by hymey; December 30th, 2008 at 12:25 AM.

  2. #12
    Lifetime Member hymey's Avatar
    Join Date
    Jan 2008
    Posts
    299

    Default

    Quote Originally Posted by joecar View Post
    Ha Ha, LJ with a 308, a "beast"... cool...
    Its a 355ci now Joecar and lots of fun, pretty scary actually.

  3. #13
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    27,752

    Default

    How much does an LC/LJ weigh... (I'm guessing about 2400 lbs with the 202, so with a 308 only a little more)...?

  4. #14
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    27,752

    Default

    And I am sorry for the hijack...

  5. #15
    Lifetime Member hymey's Avatar
    Join Date
    Jan 2008
    Posts
    299

    Default

    That car weighs 1180kg/2596 pounds.

    cheers

  6. #16
    Senior Member alian's Avatar
    Join Date
    Jun 2008
    Posts
    140

    Default

    Quote Originally Posted by hymey View Post
    That car weighs 1180kg/2596 pounds.

    cheers
    Wow, That would be scary
    Ian

  7. #17
    Lifetime Member
    Join Date
    Dec 2007
    Posts
    1,142

    Default

    Quote Originally Posted by joecar View Post
    How much does an LC/LJ weigh... (I'm guessing about 2400 lbs with the 202, so with a 308 only a little more)...?
    My 308 XU-1 had 1220kg (2685lbs) on the rego papers, probably a full tank of gas made it a little heavier than Hymey's when it went over the weighbridge.

    Great work here on the the idle quality!

    Happy New Year all!

  8. #18
    Lifetime Member hymey's Avatar
    Join Date
    Jan 2008
    Posts
    299

    Default

    With the Top loader and 9 inch and full tank it was 1180kg with the turbo 400 it was over 1200kg from the extra weight and fluid and the car had weight reduced elsewhere. The new owner has put the stroker in it I went for a run a month ago and it hits very hard when the throttle is smashed runs 10s no bottle. I mini tubbed that car myself, done all the work and wish I still had it.

    As for the idle its running nicely. I have zero in all the correction tables. And I narrowed the gap between min. idle airflow and max idle area. It is a relatively simple procedure once you get the gist of the tables. There is no set desired airflow adjust, only a bottom and top airflow limit and correction in between, which is why it is possible to obtain a better and smoother idle with more control. Or like Simon has done...play with integral tables for minor correction. If you zero the correction tables it is a must to reduce max idle area down to control TP%.

    HAPPY NEW YEAR

    Cheers

  9. #19
    Lifetime Member swingtan's Avatar
    Join Date
    Jul 2007
    Posts
    1,590

    Default

    I just thought I should remind people that are trying these idle tuning tables, that you need to tell the PCM to skip the idle relearn process after a flash. Before starting the car after a flash, turn the ignition on, then press the throttle to the floor 6 or 7 times to skip the idle re-learn process. Then start the car as normal. If you don't do this, you risk tuning th idle relearn process its self and not the idle its self.

    Simon.

  10. #20
    Lifetime Member hymey's Avatar
    Join Date
    Jan 2008
    Posts
    299

    Default

    Here is some info on PID controllers, You plug in a commanded number into the calculus equation. It looks difficult but is relatively simple calculus.

    http://www.engin.umich.edu/group/ctm/PID/PID.html

    These type of controllers are a patented design.

    Earlier operating systems have tables for all 3 but my car (08 os) only has tables for 2- ie a PI controller.

    Plugging in 0 in both tables deactivates the system but to use them effectively numbers must be plugged in both otherwise the equation wont work in some instances. (ie you cant have 0 as a denominator)

    There is some examples in the website above which shows how Proportional on its own cannot find a steady state. Integral control will stabilize to steady state faster, and derivative prevents overshoot(but of course a derivative is the outcome of a function in calculus), Integrals are also know as antiderivatives.

    The e38 has a lot of mathematics in there and it is all engineering/university stuff above high school level.

    When seting up a P-I-D controller

    1. Obtain an open-loop response and determine what needs to be improved(ie zero tables)
    2. Add a proportional control to improve the rise time
    3. Add a derivative control to improve the overshoot(some os do not have this)
    4. Add an integral control to eliminate the steady-state error
    5. Adjust each of Kp, Ki, and Kd until you obtain a desired overall response. You can always refer to the table shown in this "PID Tutorial" page to find out which controller controls what characteristics.
    Last edited by hymey; January 1st, 2009 at 02:15 PM.

Page 2 of 32 FirstFirst 123412 ... LastLast

Similar Threads

  1. Idle/Idle Transition Tuning
    By Rhino79 in forum General (Petrol, Gas, Ethanol)
    Replies: 10
    Last Post: January 11th, 2007, 04:10 AM
  2. Idle Tuning
    By lplott in forum General (Petrol, Gas, Ethanol)
    Replies: 7
    Last Post: November 26th, 2006, 06:03 AM
  3. Stock maf = perfect idle. Big maf = unstable idle. Any tuning suggestions?
    By onfire in forum General (Petrol, Gas, Ethanol)
    Replies: 7
    Last Post: July 11th, 2006, 02:58 PM
  4. Idle Tuning
    By 98WhiteDevil in forum General (Petrol, Gas, Ethanol)
    Replies: 1
    Last Post: June 19th, 2006, 03:36 AM
  5. tuning idle
    By BACKinBLACK in forum General (Petrol, Gas, Ethanol)
    Replies: 51
    Last Post: April 12th, 2006, 08:07 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •