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mrr23, hptuners discussion

This is a discussion on mrr23, hptuners discussion within the Computer & Tuning forums, part of the LSx Technical Help Section category; one thing i did today which is a big help with inital start up is up the Startup Airflow Delay. ...

  1. #21
    Senior Member mrr23's Avatar
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    one thing i did today which is a big help with inital start up is up the Startup Airflow Delay. this sets how long before the decay of the inital airflow decay is to start. stock is set to 0 camshaft revolutions. so, the decay rate starts immediately. i set mine to 500 which is just over 1 minute. camshaft spins half the amount of the cranshaft. so 500 x 2 = 1000 rpms. my idle is set to 850. so, 450 camshaft revolutions is one minute of time. this is like holding the pedal at a certain rpm until it gets to a point that it will idle on it's own.

    once you get your base running airflow set, but won't stabilize right away, this can be a buffer.

    also, use the idle Startup Airflow Initial to offset the Base Running Airflow. if the BRA is too high, then while you are driving, you'll get the cruise control effect.

    what i did is look at the Idle Desired Airflow values while it was idling and set the BRA to those values. IDA shows up in lb/min. BRA is in grams/sec. click tools and use the unit conversion calculator to convert the number.

    example: my IDA is .90 lb/min which converts to 6.82 g/sec. you then look at what engine temperature it is and put that value in.

    now, back to startup. i looked at the MAF reading right at the point where the motor starts turning over, to see how much air was coming in. so, i changed the value in the Startup Airflow Inital to match. again you have to convert from lb/min to g/sec as MAF reads in lb/min

    example: MAF at inital startup 2.00 lb/min converts to 15.15 g/sec. next subtract your base running airflow from that value and this will be what you put in the Startup Inital Airflow at the engine temp where the reading is at.


    15.15 - 10.69 = 4.46

    this will get you close. i'm actually 2.00 g/sec under this. i've also messed with the open loop eq ratio to get the fueling correct as well.

    i'll explain more as i finish testing my theory.
    Last edited by mrr23; 06-17-2007 at 07:33 PM.

  2. #22
    Veteran 0rion's Avatar
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    At one time I had mine set to 50 rotations but really didn't notice any difference. I did however notice a difference today adjusting the startup airflow initial. I'm gonna up it a little more and see where it ends up. I would have to look but I think I'm logging IDA in g/sec.
    Answer me this. When I start the car after about 10 seconds or so I can hear the car start sucking a ton more air. I'm wondering what table would make that air come in earlier?
    I took the car out today for a short cruise up the road. I'm getting an assload of knock with anything over about 50% throttle. I'm almost positive this is a lean issue since I took my ve, ifr, and everything else back to stock. I'm not gonna worry about it to much right now until I'm done with the idle. I was seeing 15:1 and above AFR with the wideband in those conditions.

  3. #23
    Senior Member mrr23's Avatar
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    50 rotations at 900 rpms is only 7 seconds.

    engine < idle < idle airflow right hand upper side is IAC Steps vs. Effective Area. i copied the values after 0 to the end, then shifted that to the left about 4 spaces
    Last edited by mrr23; 06-17-2007 at 09:16 PM.

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    thanks for the info, I think at one time I've read about moving that table to the left. I'm gonna try something a little different and see how it works. I copied and moved the first 4 to the left 4 spaces then went to the 2D view and manually smoothed the first part of the table.

  5. #25
    Senior Member mrr23's Avatar
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    another tip i was given was to switch to metric. all of the lb/min will be changed to g/sec. makes it easier to make changes.

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    maybe that's it. I switched to metric right away. Edit had a lot of metric tables so that's what I was used to seeing.

  7. #27
    Senior Member mrr23's Avatar
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    well, i scratched my whole tune and started over. just couldn't get what i wanted. after some reading through the help files and on hptuners, i devised another strategy. so far, it's working.

    i decided to try a different approach to startup and idle. instead of controlling it with the base running airflow, i made changes to the friction airflow initial. what i did was watch to see how much airflow the MAF reported right as soon as the engine turned over. it was reporting 15.95 g/sec. so,what i did was, i left the base running airflow table stock and added the rest to the friction airflow initial table. this took care of startup. then, i took friction airflow decay and reduced it by 10%, to slow the decay down.

    also, changed the target idle rpm to 900 in park and 850 in gear. when in gear, the STIT went up to just over 1 g/sec. i may set the in gear to 900 rpms as well, unless i can get the STIT fixed. seems 900 rpms is where it wants to be. when i raised the target idle rpms, it raised the STIT. so, i opened the TB up to get it around -0.50 g/sec. would really like to get it to 800, if at all possible

    here's my thread on hptuners
    http://hptuners.com/forum/showthread...1579#post91579

  8. #28
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    I added a little more to my initial startup table and moved the iac steps table. Still have a little start up surge but it settles after a couple of seconds. I made a few other changes to it including adding some more fuel via the maf table to get my idle afr lower. It worked but now I need to unplug the maf and get the ve table under control. Still seeing knock at different times under load but I'm wondering if this is still a ve table problem because my understanding is the ve plays a big role in throttle transitions. I also noticed that my trim cells are all screwed up. I set the boundaries but I must've done something wrong because they're all out of whack now. I'm gonna put them back to stock until I figure out what I did wrong. My wife works tomorrow night so I can't take the car out on the road with the kids here but I'll fiddle with the idle a little more.
    Positives:
    Drivability is actually very good. Little to no surge except at very low load steady throttle ( 35mph and cruising) and even then it's barely there. RPM's settle nicely when coming to a stop, no cruise control effect or surging anywhere. RPM's don't surge anymore going from park to drive.

  9. #29
    Senior Member mrr23's Avatar
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    mine is somewhat better. i have the shut off, if i let off the throttle at, or under 10 mph. i have some surging (idle hunting) while still warming up. if i can get rid of that and the low speed shut off, i'll be happy. seeing as my TB has no hole in it, i have been told i'll need one in the .120" opening area. debating this one. can't get a stable idle under 900 rpms. i asked roger vinci if i was asking too much of this motor to idle under 900. he said most likely won't idle under 850-900 rpms.

  10. #30
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    have you tried playing with your throttle cracker airflow to help with the shutting off at low speeds? Might be the answer to that one. I would think 900 is about right for that cam. I have a much smaller cam and I can get it to idle pretty good at 825-850 but there were more headaches that came with that so I decided to go to 900rpm's because the idle was much better there. If I get all of this figured out I may try to lower it back down there but for now I'll live with 900.
    I've been noticing that as I keep working the base running airflow table my desired airflow keeps getting lower and lower. I do have the tb blade open a little bit and that's probably why it's doing that but I'm wondering why it would continue to decrease. It would seem to me that desired air shouldn't change.

  11. #31
    Senior Member mrr23's Avatar
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    i left it alone last night. it's doing pretty good now. i've decided that 900 rpms is it. per recoomendation, removed the throttle cracker. got rid of the cruise control effect. the idle surge was from trying to get to 800 rpms. with it at 900 rpms, it's pretty much gone. that and i raised the proportional and integral enable rpm error from 60 to 100 rpms. so, at this point, startup and idle is acceptable.

    i came to the conclusion to leave the base running airflow table at stock and use the following tables:

    friction airflow decay
    friction airflow initial
    friction airflow delay

    startup airflow decay
    startup airflow initial
    startup airflow delay

    also, i worked the throttle follower decay and delay.

    one thing i was told was to try and get the desired airflow to match the base running airflow. everytime i tried, the car would surge to no end.

    was playing with SD tuning today. that's going to take some work. as soon as it came off the idle cycle, it would die.
    Last edited by mrr23; 06-20-2007 at 05:45 PM.

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    I'm gonna post up a log tomorrow or Saturday and let you see what you think about it. I'm really getting beat up on this start issue. My desired air and base air are extremely high on start up 20-30's. They settle down though by 40C and end up way to low ~5 g/sec by 80C. I just looked back at the first log I took when I still had my old edit tune in there. It looks much better than the current tune I have now.
    While the car is idling my LTIT is at zero and my STIT is 1 g/sec except for those first 10-20 seconds. It's astronomical during that time. I've been working some 12 hour shifts the last few days and have another one tomorrow but I'm gonna transfer over a log from my laptop and let you look at it and see what you think. I'm curious how similar to yours it'll be.

  13. #33
    Senior Member mrr23's Avatar
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    do this. put you base running airflow table back to stock. take a look at a log where you were logging actual start up. when it's starting and catches, see how much the MAF is reading. then take your base running airflow number for that temp and subtract it from the MAF reading. then go to the friction airflow initial and make that number the difference of the BRA and MAF.

    example:

    on mine, the MAF reads 15.96 g/sec on start up. BRA is 6.20 g/sec 15.96 - 6.20 = 9.76. i put this number in the friction airflow inital table.

    now, take your friction airflow delay and startup airflow delay and put 500 in the cells up to 40C, 250 in 60C and leave the rest zero. doing this is holding the IAC open at that opening for about 30-60 seconds. after the delay, the idle will start coming down. to slow this rate of decent, you change the friction airflow decay and starup airflow decay tables to a lower number.

    this will get you close.

  14. #34
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    I tried it the way you're doing it but had much better luck moving the IAC in park table. I think my air issues are getting closer but that first 30 seconds is still kinda surging. I can almost live with the surge I have right now for a while. I want to get started on my ve and get the car so I can drive it.

    here's a link to the idle log I did this morning.
    start up log

    current tune in case you wanted to check out my air tables, they're not right but they're getting closer

    current tune

  15. #35
    Senior Member mrr23's Avatar
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    when i moved my IAC park table to the left, i started having a lot of surging. maybe take yours and move it to the right and scale it down. something i think i'm going to play with now that i saw what it does.

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    I may give that a try tonight and see what it does. I moved it to the left last time and noticed zero difference. This round I added 2 g/sec to the IAC park position airflow and it made a considerable difference. I may try to go 2 more at 20C and see what that does. Once the car gets up to ~30C the cold start problems pretty much go away. It's that first 20-30sec when starting from stone cold. You can see in the log my stit's are still trying to add quite a bit during that time but that's way down over what it was. It's at +8 or so now I think where it was at +20 before. It was just nice to do something and see an improvement. Been a while since that's happened.

  17. #37
    Senior Member mrr23's Avatar
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    use the startup airflow delay and friction airflow delay to have it hold off on the decay on start up. my STIT are -2.59 right now.

  18. #38
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    well, I was gonna try it tonight but I'm a dumb ass. Twice now I've left my hptuner cables hooked up and my wideband turned on and ran my battery completely dead. Can't believe I keep forgetting to unhook all of that stuff. The hp cable won't run the battery down but the wideband heater will. Surprised I haven't burned up my sensor by doing that twice now. I had to buy one sensor earlier this year because I let condensation get into the sensor and ruined it. Guess I'm a slow learner, that or I just like to spend money when I don't have to.

  19. #39
    Senior Member mrr23's Avatar
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    ah, you just like spending money.

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    ok, I'm kinda seeing a trend here. I moved my iac effective area back to stock and added 2 more g/sec in the iac park table. I think I can nail down the 40-80C base air with 1 more tune. The 20C is my nemesis. I may just have to live with it until I can figure out something.
    When I start the car is starts off with a little surging then I can hear it start sucking way more air ( sounds like a vacuum cleaner) and as soon as it does that the surge goes away and my stit's start to drop. I'm gonna guess that something is decaying out right there and I need it to decay almost immediately after I start the car. I just don't know what it is that's taking 20-30sec to decay. I'm thinking the airflow initial or frictional airflow so I'll play with those a little bit. I'm moving to my in gear air next because other than that initial start I'm happy with my idle and can nail it with 1 more flash I think.
    I'm working a ton of overtime right now so it's tough to do much other than work and sleep while trying to fit some kids time in there. I'll get it though then it's time to work on that ve table. I have some knock issues that I'll have to deal with at some point but I want to get my fueling on first.

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