Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Page 2 of 2 FirstFirst 12
Results 16 to 23 of 23

Thread: 94 Jimmy Help Spark

  1. #16
    Fuel Injected! ralmo94's Avatar
    Join Date
    Feb 2020
    Posts
    51
    Got a chance to do a data log. Still getting negative timing. seems to come on at about 55 kpa, but when throttle is lifted enough to take load off SA goes back to positive even at higher map than 55. looking at the bin, I now am going to change a low octane value.

    07/09/2020 20:21:32 Scalar: Minimum Temperature for Low Octane Retard changed from 80.0 C (0xA0) to 151.3 C (0xFF).

    Does anyone think its low octane settings?

    I realized I had broken a rule of tuning. Changed a bunch of stuff and didn't know did what. So I will take this one setting at a time.

  2. #17
    Fuel Injected! ralmo94's Avatar
    Join Date
    Feb 2020
    Posts
    51
    Alright, with the low octane settings disabled, I was still seeing negative timing.
    Attached Files Attached Files

  3. #18
    Fuel Injected! ralmo94's Avatar
    Join Date
    Feb 2020
    Posts
    51
    So what I tried next was to limit the minimum spark advance. There was not a scalar named that, so what I did find was one named maximum retard. so I changed that.

    07/10/2020 17:44:33 Scalar: Maximum Spark Retard changed from -9.8 deg (0xFFE4) to 2.1 deg (0x0006). Now I longer have negative timing.

    Now the timing never goes below 4 deg. seems wierd to me since the minimum I set was 2.1, but at least it's a positive value now.

    So, moving on, I am now trying to figure out what is keeping it from running the amount of advance that if in the main table. It should be commanding about 14 deg, and its only 4.

  4. #19
    Fuel Injected! ralmo94's Avatar
    Join Date
    Feb 2020
    Posts
    51
    Looking through all I can find, I see, Cat overheat protection. Doesn't say anything about spark, but I am still surprised its enabled on a 94. I dissabled that and we will see if that makes any difference with timing.

    07/10/2020 19:46:42 Scalar: CAT Minimum RPM for Overheat Protection changed from 0 RPM (0x00) to 6375 RPM (0xFF).

    I kinda feel like I'm trying to re invent the wheel here. Has anyone ever set up an $OD tune to run only the main spark map? Seems like that would be how you could figure out what timing your engine likes. How do you know if there are variables it's adjusting for, but you don't know which ones.

    at least I have gotten rid of negative timing. That's progress. seemed pretty straight forward with h p tuners. Maybe I can get back to tuning ve now that I don't have negative timing, but I really want it to run what I set. Does no good if I don't understand why its not I have looked at Coolant Temp Adjusters, Altitude Adjusters, Everything I can think of, and at the cells I'm looking at they should not have any effect as the stock tables read 0's. Running out of ideas. I've tried to tune spark before with newer stuff, and seemed to get knock retard with stock tables, and ended up running stock timing. This however does not run the table.

    Any way If anyone has any Ideas to try you are more than welcome to suggest. I still don't understand what I changed exactly to produce a steady 12 degrees.

    I'll keep updating this thread with things I try. Seems like it shouldn't be to difficult to get a computer to do what springs and weights can do.

    Thanks for reading. I'd like to think with the high view count maybe I'm being helpful.

  5. #20
    Fuel Injected! ralmo94's Avatar
    Join Date
    Feb 2020
    Posts
    51
    figuered it out!!!
    Attached Files Attached Files

  6. #21
    Fuel Injected! ralmo94's Avatar
    Join Date
    Feb 2020
    Posts
    51
    I read an old post of someone else having about ten degrees less than the main table. What it was in that case was the altitude bias. They changed thiers to 0. I previously had zeroed all the bias values out, and skewed up. So I went ahead zeroed out just the elevation one, even though in the table it was mostly zeros. Ran the bin. Checked the data log and it seems to be running what the main table has now. Runs better. Now I can put a starter spark curve in and tune VE.



    The thread I found.


    http://www.gearhead-efi.com/Fuel-Inj...uld-command-0D


    Can't believe it was so hard to find that, but hopefully it will help others. If so please let me know. Had a lot of views, so if I haven't been helpful, I hope I was entertaining.

  7. #22
    Carb and Points!
    Join Date
    Jul 2020
    Posts
    1
    Did you end up using the BJLF bin with the $OD XDF and ADX?

  8. #23
    Fuel Injected! ralmo94's Avatar
    Join Date
    Feb 2020
    Posts
    51
    Quote Originally Posted by Mark Still View Post
    Did you end up using the BJLF bin with the $OD XDF and ADX?
    I had started out with jf, as it was the stock bin with the truck. As a diagnosis, I tried starting from another stock bin, bjlh. Didn't make any difference, and I didn't think it would. Basically same bin with different vss is what I seen. I have used both bins with the same adx and xdf I posted in the thread. Both bins are $OD

    I hope that answers your question. Main culprit seemed to be altitude, but I left low octane blank as well. seems to run what is in the main sa map now.

Similar Threads

  1. Spark help
    By Stokes1114 in forum GM EFI Systems
    Replies: 8
    Last Post: 08-17-2017, 02:37 AM
  2. new member, 1990 GMC Jimmy full-size
    By Tumble511 in forum Introductions
    Replies: 3
    Last Post: 03-02-2017, 04:33 AM
  3. 1994 GMC Jimmy 4.3l CPI
    By KC5UEA in forum Introductions
    Replies: 3
    Last Post: 12-10-2015, 01:41 AM
  4. 90 GMC Jimmy V1500, Conversion from TBI to MPFI
    By JimmyRon in forum GM EFI Systems
    Replies: 0
    Last Post: 10-17-2015, 08:27 PM
  5. Done with VE now onto spark
    By majacoby in forum GM EFI Systems
    Replies: 4
    Last Post: 11-14-2013, 02:14 PM

Bookmarks

Posting Permissions

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