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Thread: Troubleshoot surging at idle

  1. #16
    Fuel Injected!
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    I noticed the differences too. I didn't know what caused them. I assumed it was the guy who attempted my tune before. I will poke around the forum for a clean version to start with and input my changes.

  2. #17
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    As recommended I created a new bin file from one I found on here. I put in the tables for fuel, timing, egr, etc. I still have the idle hunting problem. The problem is muted when the truck is at idle in gear, but very evident in P/N. I attached the bin file I modified and the log file. Hot idle happens at the end of the file.

    I am getting tired of fighting this thing. Do I just put in a Vac Ref Fuel Pressure Regulator and put the smaller injectors in?
    To me that would add complexity, but I am not sure what else to do at this point.

    I have looked but have not found an explanation of all the parameter use equations. Can anyone point me to these so that I can see how each is used to calculate what the computer is commanding?

    Thanks!
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  3. #18
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    Why does my fuel pump voltage change when sitting at idle?

    Does ECM change voltage or does it just monitor it?

    I will be very happy and yet frustrated if my problem is something like a weak fuel pump relay.

  4. #19
    Fuel Injected! sturgillbd's Avatar
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    I'll view your bin and datalog this evening. I got called out to work yesterday eve and didn't get home until about 7:00 am this morning. I will make some adjustments to your bin and you can try them to see if it calms the idle surge

  5. #20
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    I tried a few things with no real change. I think I am at the point of bumping idle speed up to 800 or running open loop idle. Either would be fine.

  6. #21
    Fuel Injected! sturgillbd's Avatar
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    Turn the throttle stop screw clockwise another 1/2 turn. Try this bin after pulling power to PCM for 10 seconds or so to clear all of the learned values. Warm the engine up and do a short datalog with about 45 seconds of idle at the end. Lets see if this calms the surge down some.

    Brian
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  7. #22
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    So the timing change seemed to help quite a bit. The timing now stays pretty solid. It had one little bit between log 1 and log 2 where it almost died, but then rev'd back up and settled down again.
    The idle afr swings seem to be better. I wish I could get the autoprom to accept the wideband signal so I could show that as well.
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  8. #23
    Fuel Injected! sturgillbd's Avatar
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    I'll review the logs later and get some ideas. I zero'd out the idle speed correction timing tables. There were also some adjustments to the iac counts vs % airflow table and of course the spark tables. Some of this will have to be done with trial and error until you get it how you like it. Do a bin compare between the bin you posted and the edited one. You can put things back to orginal one table at a time and see which change made the most difference. I noticed your IAC did move a lot and there are some proportional adjustments that can be made to calm that down also.

  9. #24
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    Thank you for the help. I will definitely use these corrections.

  10. #25
    Fuel Injected! sturgillbd's Avatar
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    The adjustments have definitely calmed your surge problem. Only thing I see that stands out is your IAC counts are still pretty high at idle. I would turn the minimum air screw clockwise until you have 0 counts at idle with engine warm. I would turn off engine for about 30 seconds then restart. Let the engine get back in closed loop and settle a couple of minutes then turn screw counterclockwise until you get 8-10 IAC counts . It may take a couple of adjustments to get close but you need more air across the butterflies and less through IAC. If your throttle body has never had the plug removed, you will have to remove the plug first. In this pic , it is called minimum idle screw. IAC counts should show while connected and engine idling with the data dash pulled up.
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  11. #26
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    When I get down close to that few IAC counts, I get close to triggering tps off 0%.

  12. #27
    Fuel Injected! sturgillbd's Avatar
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    When you turn key off for 10 seconds or so, and turn key back on, the pcm resets the zero throttle position.

  13. #28
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    Now that we have made some progress on the idle and running, I have another question. It seems like when coming to a stop, or slowing down in general, the truck is holding on to the gear. Which parameter am I missing that would release it from engine breaking quicker?

  14. #29
    Fuel Injected! sturgillbd's Avatar
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    There are decel fuel cutoff parameters and also tcc lock/unlock parameters. Does it feel like the torque converter isn't unlocking or engine braking? I have a manual trans so I cant be of much help on Auto parameters. There are several on here who have done tuning on the trans parameters if that is what you are needing help with.

  15. #30
    Fuel Injected! woody80z28's Avatar
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    http://www.gearhead-efi.com/Fuel-Inj...unerPro!/page3

    There's info there how I set up my AEM wideband. I also had trouble with the 0-5v for a bit.

    Fighting my own surging idle on my v6 of similar cam duration too...
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1)
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D)

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