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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; I did end up doing a log today and read both my stock flash and my current flash with hpt. ...

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    Veteran 0rion's Avatar
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    mrr23, hptuners discussion

    I did end up doing a log today and read both my stock flash and my current flash with hpt.
    Tonight I worked on learning a little about the scanner and histograms. That's the key to getting the car right I think. If you can get a handle on how to process your logged info it'll tell you what it's looking for. I'm just wondering if my thought process is right though.
    I'm looking at my idle first so I created a histogram using the idle airflow table (idle airflow vs coolant temp vs (gear p/n) and plotted my idle desired airflow within it. The first thing I noticed was my averages were going to be wrong in the first temp range because it was counting before the car was running so I tried to apply a filter [pid.12]>800. What I was trying to do was filter everything less than 800 rpm's. It seems to have worked because my desired number seems like a more realistic number. Now I just have to figure out how to use that data. My actual is way above my desired and neither is really close to what I'm commanding with my tune. I'm guessing there are several factors that go into that. I just gotta chase them all down.

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    Senior Member mrr23's Avatar
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    dark bowling green
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    what you are supposed to do is copy the entire info out of the histogram, then go to the Idle Airflow table, highlight the entire table, right click, Paste Special, Multiply by %.

    when you get closer, you Multiply by % - Half.

    here's something a guy from SCT told me to do

    The throttle follower decay in gear will help the stalling by slowing down the IAC response to the throttle

    closing. Decrease the values to simulate closing the throttle slower .Works similar to the old vacuum dashpot stuff on carburetors.

    “Startup airflow initial” is the starting position of the IAC when the key is turned on. Increasing those values will help with startup

    You should be able to datalog IAC adaptive corrections to get the base airflow set. Adjust it to minimize required correction

    to maintain desired airflow. A/F should be close when your trying to get airflow set as that can effect engine load and stalling.

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    I'll give that a shot. I'm hoping to be able to spend a little time on it this coming week. I'll try a few flashes tonight after the kids are in bed. The way it sits right now I have 3 issues that I would like to deal with. Idle increases then falls back to normal when car is put into gear, idle dips a little when coming to a stop, and part throttle surge.

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    Ok, I tried it using the actual airflow and doing a special paste last night and that drove my stit's even more negative so tonight I used the stit+ltit method and that got them way closer but still a little off. at 20c I'm roughly -.50 then it goes to -2.xx through 40-60c then to +.40 at 80c. That's down from as high as -4.xx from the first attempt. Those are all averages. I also hooked my wideband up to the eio although I don't really trust it's numbers because I'm using a sniffer pipe and my exhaust has several known leaks. I was showing ~18-1 at idle. I did notice it never seems to go to closed loop idle because the afr never switched to 14.6:1, it stays lean the whole time and I stay in cell 17 the whole time. I know when I drive it that it goes to closed loop but just not at idle. That'll require some reading. I used the vcm controls tonight just to play around with them and see what happens. I raised and lowered my idle timing by as much as 4 degrees. It seems to idle best right where I have it so I'm not touching the idle timing. It currently idles in the 20 degree range but raising another 2 degrees made it idle worse and lowering it a couple made no difference. I also manually commanded closed loop but didn't see any changes at all. I'm gonna play with it again tomorrow night after work and see what I can come up with. I have a feeling I'm trying to idle the car a little to low to begin with. I have it set at 800 rpms but the car idles pretty decent so unless there's any issues with driving it and coming to a stop I'm gonna try to leave it there.

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    Senior Member mrr23's Avatar
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    well, if you are truly lean, then adding timing will make it idle worse. another thing i did was log the MAF in Hertz and made changes at the 3000-3600 Hz area where it was logging at. it's another way to add fuel.

    my 408 was idling at 900 rpms. i'll work to try and get it to around 800 rpms when i get it back together.

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    I added a little back to the ve table in the idle cells because I think I had reduced that 3rd column a little to much. I added timing back to it and the idle did get a little better. Seemed to smooth it out some. I'm idling ~23-24 degrees now. Still not quite sure I got a grasp on the RAF side of it but a little more playing around should net me a little. The last tune I flashed my stit's are all near zero but my ltit's went a bit more negative ( -1.79). If I knew for sure my afr was fine my idle really is pretty good. I really don't have any problems with the way it idles the way it sits now. I'm getting a bung welded on next week so I can move that sensor up closer to the headers. My cam has 8 degrees of overlap so I'm not sure how much that's going to skew the wideband numbers. Next up is the throttle follower to try and get rid of the rpm dip after a rev. It doesn't dip way down but it does dip a couple hundred rpm before it comes back up.

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    ok, I'm starting over. I adjusted my set screw back in a little tonight so I'm gonna redo the RAF. I read that you want your TB volts .45-.55v and mine was .65 so I turned it in some to see what that does. I did notice that my RAF table was getting lower than it should've been as I was adjusting it. I also put another 50rpm back into the idle. It really seems like it idles best at 900rpm but I'm gonna mess with it at 850 and see if I can get it smooth there.

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    Senior Member mrr23's Avatar
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    i did my idle tuning today on the 408. i tried fixing it with the base running airflow in the idle section. it was ok, but not getting me where i wanted. i ended up tuning it via the MAF. logged the MAF in Hertz and found where it was logging at and copy and paste multiply by % until the LTFT were -5% good enough for me. now to get the dying when letting off the throttle suddenly in low rpms is next.

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    I started over but that didn't go very well. I set the TB back and it wouldn't idle. I ended up going back to my last good tune and backing the set screw out again. I'm really trying to get it without drilling the blade but I think that's probably what I should do. Just drill the blade out a size or two bigger. I still just don't have a firm grasp of how the idle air works. When I set the blade back I added tons of air to the base at 20c and at the start up initial with pretty much no effects. I looked at some tunes for cars that were comparable to mine and I had way more base running airflow than they did so that's why I set everything back and bumped the set screw out a bit. I think I'm gonna work on the idle fueling and richen it up a little bit then move on to running airflow in gear. I'm pretty happy with my idle as long as the set screw being out doesn't mess up what cells the car is running in.

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    Senior Member mrr23's Avatar
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    one thing i found, when using the idle airflow table is while you are driving along and let off the throttle, it won't settle down. like it's in cruise mode. so, telling it it has more air at idle is causing a second issue, for me.

    using the idle airflow for start up and initial warm up works. just a matter of balancing the two out.

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    so how much did you adjust your maf table to add fuel at idle? I tried adding fuel to my idle last night with limited success. I raised the ve and maf but didn't really notice the afr improve a whole lot. I also increased the throttle follower decay trying to remove the dip after a rev. It does let the rpm down slower but it still seems to bottom out before coming back up to idle.

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    i logged the MAF and did a copy < paste < special multiply by % the first time. then did a copy < paste < special multiply by % - half the next time around. must've added around 6% in the 2875 - 3250 Hertz area.

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    My first order of business when I get back from vacation next week is to have a bung welded on so I can move that wideband. It has to be somewhat accurate because it does show 14.6-7 when cruising. My idle afr though is pretty jacked up. It bounces around a lot which is probably a combination of reversion and sucking a little air up the tailpipe. Mainly though it hovers in the 17:1 range even after it goes to closed loop. So far adding fuel hasn't really shown up on the wideband. I'll have to look and see how much I added but it was probably 5-6% and the wideband didn't show it get any richer, maybe a hair.

    Any idea where I should start looking to get better throttle response and to keep that idle from dipping after a rev? I just kind of figured the throttle follower would help the dip and it did slow how fast the rpm's come down but it still lets it dip. I'm wondering if it's still in the base air but those numbers are kinda high as it sits. I really don't think they need to come up any more. I'm gonna do a good log and post it at hptuners and see if someone there can steer me in a direction because I've made very little progress this week on it.

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    Senior Member mrr23's Avatar
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    mine idles around 15.5-16:1 i've tried adding fuel to bring it down to no avail. my cruising is in the 14.5-15.5:1 range.

    my throttle response if fine. i don't know where to go for the dip and stall problem we both have. just got through doing a start up and 30 minute drive logs. going to post on hptuners forum and see who ponies up to help.

    i tried making a histogram to monitor the IAC, but didn't work.
    Last edited by mrr23; 06-09-2007 at 07:38 PM.

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    excellent find. I'm going on vacation in the morning and will be out of town until next weekend so I won't be able to play with the car until then. Keep me posted if this helps you or not. It sounds like the right track to be on without fighting the base air table back and forth.
    few others
    idle dips

    another good one explaining how to find optimum idle timing and the last post helps with dips

    There's a lot of info at their site...almost too much. My brain starts to hurt after about 5 threads. Currently I've been adjusting my old edit tune because it at least had the car idling. I think while we're on vacation I may start over with my stock file and try to get back to the same point I'm at now. We have a 10 hour drive ahead of us so it'll help kill time. The reason being is I've adjusted so many things here and there I've honestly lost track of where I'm at. I kept a word file on my old computer with every adjustment I made with edit. I can always use that as a reference to undo certain things but I think the best bet is to just start over with a stock file.

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    Senior Member mrr23's Avatar
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    i've been getting some help from Russ K over on hptuners forum. for your idle tuning, you can try my config file. i integrated his idle config with my config to get it to work. i'll have to email it to you. board say invalid file.

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    yeah, send it to me when you get a chance. ibzrg6@aol.com

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    Senior Member mrr23's Avatar
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    sent. tried contacting you through AOL IM, but says you are not online.

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    yeah, I have everyone blocked.
    I started over on my tune while I was on vacation. Got pretty much everything copied over that I wanted copied over then hit a snag when changing the speedo for my gears. I guess since it's a 98 it's not as simple as just entering tire size and gear. You have to figure it manually. It'd be kinda nice if that was in the help file. I looked from about Elizebethtown, KY. to Paducah, KY. trying to figure out why I didn't have the damn places to enter the gear change. I ended up just using the size that got trasferred over from my edit tune which was correct, stock tire size with 3.73's equals 6.68.
    I'll load that cfg file and mess with it tomorrow. I have to go get my boat cleaned out to take fishing for flatheads tomorrow night.

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