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Thread: P59 dbc 3bar turbo Silverado tune.

  1. #21
    Quote Originally Posted by reubone View Post
    Any updates on this?
    well I can finally say this issue has been solved. It was the adaptive idle settings jacking with the stit and ltit that was the final piece of the puzzle. The update rpm error was set to zero. I would get up to temp at idle and the stit would just keep going lower and lower and lower. I set that update rpm error to 60rpm and now I get a consistent number. Dialed in raf it starts right up and the raf is a consisten number instead of falling downwards no matter what I did. I could close the throttle body and it would still 0 out until the throttle was almost completely cold then it would max out. Crack the throttle a touch and back to 0 the timing could keep the idle as long as it had any air basically so it would keep bottoming out the stit. The cams natural rpm fluctuation was killing the stit and ltit.

  2. #22
    Quote Originally Posted by bbowerman View Post
    well I can finally say this issue has been solved. It was the adaptive idle settings jacking with the stit and ltit that was the final piece of the puzzle. The update rpm error was set to zero. I would get up to temp at idle and the stit would just keep going lower and lower and lower. I set that update rpm error to 60rpm and now I get a consistent number. Dialed in raf it starts right up and the raf is a consisten number instead of falling downwards no matter what I did. I could close the throttle body and it would still 0 out until the throttle was almost completely cold then it would max out. Crack the throttle a touch and back to 0 the timing could keep the idle as long as it had any air basically so it would keep bottoming out the stit. The cams natural rpm fluctuation was killing the stit and ltit.
    well its better but still not fixed. i can do an iac counts vs effective area modification. (idle desired/dynamic airflow*iac counts) it never gets close just keeps saying its off no matter how many times i do it. I can set the iac counts at 50 with the truck completely warm then kill it and restart it and they are back up to 120-130 or bottoming out the table no matter what I do. beginning to think its an ecm error of some sort. the stit will just keep going down too at one point it was -7grams when my raf in that area was at 8grams. no way its idling at 1 gram of airflow. dynamic air seems to be fairly consistent but idle desired is all over the place.

  3. #23
    Ended up being that my iac valve is from a 4.3 s10 the throw of the valve is different than the one on a 5.3 at 0 counts it's longer than an LS iac and at 310 counts it's barely opening in this throttle body. The iac hits the seat of the throttle body at 100counts so any counts under 100 are doing nothing. And 310 counts isn't enough to cold start it's barely enough for a hot restart. Getting another tomorrow to resolve the issue.

  4. #24
    Okay it wasn't that. I put a brand new gm tps and iac in it. The tps volts are at .31 and tps is 0% what is happening is I will get the engine completely up to temp (176-178 with current thermostat) and I try to set the iac counts to 40-60 range. The counts will be at 220-240 and I will close the throttle body 1/16-1/8 of a turn and the iac counts will slowly start going down until they hit 0 I will then have to turn the throttle body set screw 1/4 turn to get the iac counts to 50-60 which is more turn than I originally took out. It sits and idles at 50-60 which sounds good but I then turn the key off and immediately restart iac counts go to 220-240 range and stay there even after idling for 4-5 mins. I repeat the process and get the same result every time. For now I just open the tps a little more than it needs and the iac counts go to zero I disabled ltit to stop it from learning. Doing this it will start and run but counts go to 0 and stit produce large -g numbers. I'm stumped on this one.

  5. #25
    Any idea on what to try next? I have a new wideband sensor on the way currently just to rule that out but I don't think that's it.

  6. #26
    Btw on the post above I meant open the TB when the counts where at 220-240

  7. #27
    I have solved this issue finally. I had to do some research at the shop myself to finally figure this out. But it was in the throttle body and iac. Don't believe all the iac counts stuff you see or hear on these forums. With a stock TB or an aftermarket with a large iac port they are correct but with these they aren't. The max "EFFECTIVE" range of the iac is 310 counts on a gm TB I cranked those numbers up and found out my iac still opens all the way until just below 400 counts. At 50 counts this iac barely flow anything at all. Basically between 0-100 counts on this TB is very little added air. Between 100-220 actual does a bit and 220-400 is plenty of air. setting my hot idle counts to 120 and giving the iac the range to 400 count in the effective area and retuning the effective area solved it all. Cold starts are good, hot starts are good, and the stit doesn't just go straight down or up it is stable.

  8. #28
    Advanced Tuner
    Join Date
    Jun 2007
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    Finland, Europe
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    548
    Post your tune, please.

  9. #29
    Quote Originally Posted by Pekka_Perkeles View Post
    Post your tune, please.
    here it is. it is a scaled tune injectors are 88lb actual. its scaled for timing control in boost. it starts up now at any temp. this truck runs super hard for it being a 5.3 it has ported 706 heads and flat top pistons (4.8) it was 10.2:1 compression. its flex fuel also. i drive it around on pump gas but it always has at least 50% content if im beating on it although its safe on both. currently on 15psi.
    Attached Files Attached Files

  10. #30
    Just wanted to make an update here my last post was incorrect. I had to read and do some testing of how the Iac works to find my problem but it is solved for real this time. so there is no way for an ecm to read the counts of an iac. to find the "0" counts it send the iac in until it stop and then it pulls out from there. there is no set amount of steps in the iac motor it is simply a rotating female thread and the iac pintle is on a threaded rod if you take the iac out of the bore and use hpt to control the iac counts you can screw the entire thing out. the problem I was having was in my wiring harness. my constant hots where ran to a keyed hot this caused the ecm to lose "memory" of the iac counts and everytime i started it they where different. causing negative stit sometimes and positive stit sometimes. i fixed that and set counts to 60 at hot idle and it now sits at 60 when warmed up evertime i restart the truck. if you need more info on the iac you can send me a pm and i can share more of my findings and how i tested this. I also found a way to get more air out of the iac on a ebay 92mm the iac wide open wasnt letting the iac come back far enough to open the passage completely so I added a thick oring which moved the iac valve out some but it still had plenty of room to go to 0 counts without unthreading. this iac has plenty of airflow when open now and is functioning great.
    Last edited by bbowerman; 03-01-2023 at 06:54 PM.