car wont start when hot.....

Discussion in '1994 - 1995 Specific Tech' started by Green 94 5.0, Mar 26, 2007.


  1. Green 94 5.0

    Green 94 5.0 Founding Member

    Joined:
    Mar 25, 2002
    Messages:
    2,596
    Likes Received:
    7
    Trophy Points:
    49
    Location:
    Ft. Lauderdale, FL
    cold starts are perfect and immediate, but warm starts and i have to be on the gas to get her to turn over. the basics are a 331 stroker with a vortech s-trim and 42's with a pro-m 77mm to match. what should i be looking at in the tweecer to get this resolved? im using a j4j1 bin with all the basics changed, but no changes to anything regarding a/f.
     
    #1
  2. tjh566

    tjh566 New Member

    Joined:
    May 22, 2004
    Messages:
    611
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Northern Va
    I sorta have the same problem, cold start, one crank and its goin, hot start it takes awhile. Looking for a solution myself.
     
    #2
  3. BobCat

    BobCat New Member

    Joined:
    Feb 13, 2001
    Messages:
    20
    Likes Received:
    0
    Trophy Points:
    0
    ISC Crank Duty Cycle
    and
    crank_fuel_plusewidth



    Also make sure your inj comp for battery voltage is dialed in and the min pulse width has been adj. If you cant get it figured out post up a tune file and I'll make a few changes you can try.
     
    #3
  4. final5-0

    final5-0 Mustang Master

    Joined:
    Apr 7, 2003
    Messages:
    6,817
    Likes Received:
    3
    Trophy Points:
    79
    Location:
    DFW Texas
    I found some info from an older thread back in 11-05 that may help so
    I just pasted it here for you :D

    Three fixed parameters in the pcm fuel tables come into play when talking about startup.

    1) Time
    2) Load
    3) ECT

    We are dealing with two fuel tables.

    1) fuel_table_base_OL
    2) fuel_table_startup_OL

    The base table is where you see the commanded ratio and it is used during warm up conditions.

    The startup table is where you see values that are subtracted from the base table to give you a fatter ratio and time comes into play here.

    You asked about hot start conditions so lets use that as an example.

    btw, we're gonna use an unmodified j4j1 file for our little example.

    Say you've been driving around and go in the house for a while and decide to go somewhere else. When you start the car for the second time, the ECT is 180*

    Most NA h/c/i combos will idle at a load of say about .20 to .30 so we will use that load factor.

    Looking at the base table you see the pcm is commanding a ratio of 14.302 at that load value and ECT.

    Looking at the startup table in the 180* temp column at 0 to 6 seconds you see the value of 1.716. Notice as the time increases, the value decreases until finally at 40 seconds, the values in the table are no longer used.

    Here are the commanded, startup, and final ratio values

    00-06 secs cmd 14.302 startup 1.716 final ratio of 12.586
    07-10 secs cmd 14.302 startup 1.487 final ratio of 12.815
    11-20 secs cmd 14.302 startup 1.259 final ratio of 13.043
    21-40 secs cmd 14.302 startup 0.572 final ratio of 13.73

    At this point in time, you most likely go from Open Loop to Closed Loop conditions and the O2's are calling the shots to achieve the pcm's goal of 14.7 CL happiness.

    The Fix is to go to the 210 & 240 ECT columns in the startup table and zero out those entire columns. If need be, you could always play with the values in the 180* column as well.

    Grady
     
    #4
  5. Green 94 5.0

    Green 94 5.0 Founding Member

    Joined:
    Mar 25, 2002
    Messages:
    2,596
    Likes Received:
    7
    Trophy Points:
    49
    Location:
    Ft. Lauderdale, FL
    grady, i dont see those tables. i am using the cbaza strategy. the closest i can find a match to those tables are for the a9L.
     
    #5
  6. BobCat

    BobCat New Member

    Joined:
    Feb 13, 2001
    Messages:
    20
    Likes Received:
    0
    Trophy Points:
    0
    Decrease the crank-fuel plusewidth and increase the IAC on the functions that I posted and it will take care of your problem.
     
    #6
  7. final5-0

    final5-0 Mustang Master

    Joined:
    Apr 7, 2003
    Messages:
    6,817
    Likes Received:
    3
    Trophy Points:
    79
    Location:
    DFW Texas
    Gee Roger :scratch:

    Those tables have been around for as long as I can remember :D

    I have seen some say on the Tweecer site the newer software
    (which I don't use btw) has had some of the definition names
    changed but I could not say if those two tables are in that group :shrug:

    I would also say the method BobCat put up has a focus on the
    cranking time period where as the info I gave is for after the
    motor has fired :)

    I've seen some say they divided the old and new size inj for a
    starting place to tweec with the cranking stuff. You are just
    trying to cut down the fuel as the new inj is now much
    larger than the old ;)

    Grady
     
    #7
  8. Green 94 5.0

    Green 94 5.0 Founding Member

    Joined:
    Mar 25, 2002
    Messages:
    2,596
    Likes Received:
    7
    Trophy Points:
    49
    Location:
    Ft. Lauderdale, FL
    well that would explain it. i have the newest version of the software installed.
     
    #8
  9. final5-0

    final5-0 Mustang Master

    Joined:
    Apr 7, 2003
    Messages:
    6,817
    Likes Received:
    3
    Trophy Points:
    79
    Location:
    DFW Texas
    That Sucks :chair:

    You'd think the latest and greatest would add more options
    NOT
    Take them away

    Maybe they are just named something different :shrug:

    The Base OL table has load on the left and ect on the top

    The Startup OL table has time on the left and ect on the top

    I took a quick look at the functions BobCat talked about.

    It would seem to me you could find some help with the function
    fuel_crank_PW_multiply_ECT

    My reasoning would be since your current inj's are about twice
    the size and you are talking about hot issues.

    You could try half the value for temps 150 and up :shrug:

    Grady
     
    #9
  10. tjh566

    tjh566 New Member

    Joined:
    May 22, 2004
    Messages:
    611
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Northern Va
    yeah, ive installed the B3U or w/e it is (latest once) and alot changed, alot of table names are different, ect.
     
    #10
  11. final5-0

    final5-0 Mustang Master

    Joined:
    Apr 7, 2003
    Messages:
    6,817
    Likes Received:
    3
    Trophy Points:
    79
    Location:
    DFW Texas
    That seems counter productive :bang:

    A lot of those names were the same across the whole self tuning
    community with EEC Tuner and the various software revisions
    for Tweecer ..... up until this latest version :shrug:

    Its no wonder most of those "really smart peeps" on the Tweecer site
    have abandoned CalEdit and started to use editors that work
    with the bin file.

    Yet ... One more valid reason in my eyes ................

    I'll just stick to Good Ole V1.20 ;)

    It works and the bugs are fairly minimal :D

    Looks like I'm gonna be less and less of a help for others as time
    marches on :shrug:

    Grady
     
    #11
  12. Green 94 5.0

    Green 94 5.0 Founding Member

    Joined:
    Mar 25, 2002
    Messages:
    2,596
    Likes Received:
    7
    Trophy Points:
    49
    Location:
    Ft. Lauderdale, FL
    you wouldnt happen to have the 1.20 install files handy would you?
     
    #12
  13. final5-0

    final5-0 Mustang Master

    Joined:
    Apr 7, 2003
    Messages:
    6,817
    Likes Received:
    3
    Trophy Points:
    79
    Location:
    DFW Texas
    Yes Sir

    I don't know if I could call it handy as I don't remember where I got
    it stashed but ... I got it somewhere and I can dig it up if you wish.

    If you wanted to see those tables .......

    A easy way for you to see them unmodified and my tweecs to them
    would be for you to download the file of my complete j4j1 tune
    in screen shots from my site.

    Grady
     
    #13
  14. Green 94 5.0

    Green 94 5.0 Founding Member

    Joined:
    Mar 25, 2002
    Messages:
    2,596
    Likes Received:
    7
    Trophy Points:
    49
    Location:
    Ft. Lauderdale, FL
    if you could find them that would be great.....if not, i refer to the screens on your site. thanks for all the help grady.
     
    #14
  15. Green 94 5.0

    Green 94 5.0 Founding Member

    Joined:
    Mar 25, 2002
    Messages:
    2,596
    Likes Received:
    7
    Trophy Points:
    49
    Location:
    Ft. Lauderdale, FL
    well joe came over this morning and we got the surge down to a minimum. the tps voltage was way off reading 1.3 when we started. it is now sitting at 0.95 which brought it down form a 750rpm surge to maybe a 100rpm jump. once we get the timing set 100% im going to focus on the hot start issue a little more. the reason i mention what we did is the car seems to run a bit longer now on hot start than it did before.
     
    #15
  16. Green 94 5.0

    Green 94 5.0 Founding Member

    Joined:
    Mar 25, 2002
    Messages:
    2,596
    Likes Received:
    7
    Trophy Points:
    49
    Location:
    Ft. Lauderdale, FL
    UPDATE: the timing is at 10* and the tps is at 0.965. now she runs but we are back to the surging again. she is running so rich it burns your eyes to be next to the car after it has been on for a few seconds. any idea what tables to modify to lean it out at idle?
     
    #16
  17. final5-0

    final5-0 Mustang Master

    Joined:
    Apr 7, 2003
    Messages:
    6,817
    Likes Received:
    3
    Trophy Points:
    79
    Location:
    DFW Texas
    Do you have a wb and if so ... what is it showing currently at idle :shrug:

    What are your K's now doing :shrug:

    Here are a few things ... but ... you may have already done them

    Low slope at 42
    High slope at 50.4

    Load in breakpoints for 42's

    Cut your minimum pulse width in half

    Grady
     
    #17
  18. Green 94 5.0

    Green 94 5.0 Founding Member

    Joined:
    Mar 25, 2002
    Messages:
    2,596
    Likes Received:
    7
    Trophy Points:
    49
    Location:
    Ft. Lauderdale, FL
    i do have a wideband, but as of now it isnt in. i switched mid pipes and need to get another bung welded. im going to try a few of those things and see if any of them help.....thanks again for all the help grady.
     
    #18
  19. final5-0

    final5-0 Mustang Master

    Joined:
    Apr 7, 2003
    Messages:
    6,817
    Likes Received:
    3
    Trophy Points:
    79
    Location:
    DFW Texas
    No Prob :D

    Really ... for Closed Loop Tuning ... since you can datalog

    You can use the K values and obtain a very stable tune without a WB ;)

    Lots of good info about slopes, breakpoints, and other stuff which pertain
    to dialing in all the inj values can be found in EEC Analyzer.

    Let us know about your progress :nice:
    and
    A bunch of folks run 42's over on the Tweecer site :)
    and
    Their search engine is fairly decent :D

    Grady
     
    #19
  20. final5-0

    final5-0 Mustang Master

    Joined:
    Apr 7, 2003
    Messages:
    6,817
    Likes Received:
    3
    Trophy Points:
    79
    Location:
    DFW Texas
    Hey Roger :D

    I Hosed Up on the above posts :bang:

    I told you to load in the breakpoints for 42's

    I was just having a ... Senior Moment ... when I posted that stuff :rlaugh:

    I should'a used the word ..... offsets ;)

    Sorry about that :(

    Grady
     
    #20

Share This Page