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Thread: Injector timing and transients

  1. #41
    Got a ways to go but getting there. Just to verify something Mr Huggins has said before.(thank you) Don't change transients in the map that you run like for me would be 60-70 kpa then you can log your lean and rich spots in the upper and lower areas then interpolate between. It's not like stock where its the same # from top to bottom. I ended up build a histogram and using throttle position as a filter

  2. #42
    hey guys with the new injection timing the truck doesn't feel as explosive. what I mean is it seems to take longer to build boost? I looked at the torque its making more I the upper rpms, but it don't feel like it. what? heres a copy of before and after boundary ect change. the first time I just added 30 degrees all the way across on boundary. that feels better than what I came up with using the worksheet.
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  3. #43
    Advanced Tuner ttz06vette's Avatar
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    This has been my experience. Two areas that impacted transients for me were impact and gain. Although stock is the same value In temp column, the ECU seemed to respond to the change in values from one cell to another vs. just increasing them all.
    With all of that said, I was using these tables for years as a patch for heat soak with my sheetmetal intakemanifold. Car ran fine until under hood temps got HOT. Then I would get a lean tip in only in the low airflow off idle areas. For years this worked for me by bumping up impact and gain, but it clearly was a patch as it fixed the problem, but my AFR?s would shoot from 16 to 13 then settle back at 14.7. I also tried short pulse. That worked as well but it had the undesirable effect of richening up areas I did not need it to like idle. The final and correct cure to my problem was by dialing in VVE and moving my MAF enable RPM to 2500 where I was pure MAF before. So in essence I dialed in VVE and work off Speed density in those low RPM transient problem areas. Matching the timing tables in the low airflow areas also helped along with increasing idle airflow in the higher gears where the tip in was happening. Lot of work but I no longer get the large AFR swings I did.
    Last edited by ttz06vette; 05-28-2020 at 07:43 AM.

  4. #44
    Yeah I couldn't totally rely on MAF either due to cam, I think I had crossover at like 3500-4000 I'm running SD only right now and like it seems more responsive

  5. #45
    hey take a quick look, is the short pulse adder keeping from me from going lower than 0.7ms IPW?
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  6. #46
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    short pulse adder just helps the pulse when they are small, it dosnt actually add to the pulse its like a prime time it needs so when it does pulse it is correct, its a part of the injectors characterisation, the min PW will be a minimum for any PW i believe

  7. #47
    I understand, but is the adder keeping me from going less than 0.7 ms

  8. #48
    I was hoping it would help with decel.

  9. #49
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    if the adder was doing anything to stop it its only a 0.09 ms short pulse at the .7ms commanded so its barely there, must be something alse going on is it in decel fuel cut or just deceleration ?

  10. #50
    DFCO is disabled, in the low kpa areas like 30-40 it's rich 10-15percent. I'm running SD and can't seem to remove enough fuel thru the VE table. Injectors are FICs 52# came with good data. Logging I see no less than 0.7-0.8 and noticed the pulse adder. Reason I ask if you add the pulse adder @ the advertised min inj pulse it comes out to 0.7. today I'll remove the adder and see what happens.

  11. #51
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    it may lower a smidge as u will be giving it less time to actually pulse, enable the DFCO again and see what it reads it should sit lower, there can be left over fuel in ports during decel that will slowly go thru as its under a vacuum now so its all slowed down, are u decelerating for a short time or a long time ? if its short try to keep it going longer to see if it leans out as it uses up the left over fuel, just as a sample i had an issue with some injectors and they would dump 100% duty on cranking for a second flooding the engine instantly but if i then unplugged all injectors and started it up it would run for 10-15 seconds on the fuel left over

  12. #52
    Injector info is HUGE! I'm revisiting the tune after learning more about it. I installed these FICs cause I couldn't get decaps right. I actually smelled fuel in oil that was it I changed them out. Yeah I could use DFCO wanted to try without it was hoping to get lambda during decel, I know factory did it but IDK about running that lean in elevated engine temps turbo puts out a lot of heat

  13. #53
    After thinking about it the left over fuel may be what I'm seeing I'll pay more attention today

  14. #54
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    i even noticed a little rich tip out from cruise to decel only after changing to an overrun alternator pulley so even that bit of less effort of the alternator free spinning for those couple seconds can show a difference in engine fueling

  15. #55
    The pulse adder was keeping the minimum at 0.7 I zeroed adder down to 0.4 now I'm seeing 0.5 on the logs and running lean on decel. So yes the pulse adder IS added ha! After looking over the tune I put back as much stock as I could and build histos to get better data in operating temps only. IVT and ECT.On the last run I used the worksheet boundary values and other than the way it sounds torque was very similar. Maybe I'll get better mpgs.

  16. #56
    Oh yeah on the log you can see when you let off it goes rich then swings lean and stays lean. Like you were talking about the leftover fuel

  17. #57
    Ok on the transients settings is tip in the impact table and tip out the evap table? I've been working on this today but you guessed it I've confused myself again. On tip in I get a quick lean spike and the higher the IVT the more severe it also gets worse with higher kpa. That sounds more like evap to me. IDK I'm dizzy

  18. #58
    heres an example of what I'm trying to explain. is this a transient or injector issue?
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  19. #59
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    usually if the value dosnt go as low as the value in the cell there is something alse also adding to it so lowering the SPA prob helped but its still not the primary cause, looking at mine i have higher numbers then yours in my SPA on 1000cc inj and i still go down to .7 on decel, the transients will prob be the impact still for fuel on wall decel as its not lost to evaporation its just on the wall from the previous fueling event, u can use the manifold pressure so the 20kpa cell at ur IVT in impact factor if that cell is lower then the MAP before it will take more fuel out for that shift so u can adjust each one for the shift in MAP, i like to keep the MAP areas where i drive the same then maby lower the 20kpa cell to see if it helps in decel and u can try that in the evap also as both might make a bigger improvement if it works

  20. #60
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    u got a cut going on in there ?