Idle Tuning Concepts and Some Final Idle Tuning

hey guys it's Randy with low buck LS here again and this week we're gonna do a little follow-up on our cam tuning video from this week but first I just wanted to say I just noticed we passed 400 subscribers on the channel so thanks a lot to everyone who's taken the time to subscribe and to comment and yeah it's a channels growing slowly but it's growing so yeah and I actually wanted to start off first section as this video oh it's always weird when I'm out filming and somebody drives by I wonder what what they think of like why is that guy talking to his phone but anyways on my last video we did the cam tuning to get the truck to idle decently there's still a few tweaks that I will make towards the end of this video but I got a question on that video or a comment from I think it's name is I don't know if I'm saying this right but philistine oh and he just asked if I could go into a little more depth as to why I changed basically what why I did what I did so I actually put together a little PowerPoint presentation here with some of the concepts of idle tuning after you do a cam swap so we'll fire up the computer here and walk through that PowerPoint and then we'll hop in the truck and do a little more tuning and just do a few more tweaks to get our Idol dialed right in after this cam swap so we'll hop on the computer now and go through this powerpoint of you know basic cam idle tuning concepts or talk to you in a bit okay guys like I said had a question and thanks to Phyllis Dino for asking the question and so I just made this little PowerPoint here to go into a little more detail as to what changes I made and why I changed them so let's start with what why we even need to change our idle settings so basically aftermarket cams obviously that's the reason we put them in is because they're more efficient and make more power than a stock cam but that's only in the RPM range that they're designed for like for that camshaft I bought the summit 8701 it's range is 2200 to 6500 rpm so in that range it's more efficient and makes more power than the stock camshaft but below that rpm range and an idle the aftermarket cam is less efficient than the stock camshaft and that's because of the increase in the overlap between me and taking exhaust lobes like my cam isn't quite there but on some of these cams where you've got like a positive overlap you're basically for a short time your intake and exhaust valve are open at the same time so it basically makes the cam less efficient at idle and low rpm so that's why my truck wouldn't run with those stock idle parameters the new cams less efficient at idle so it needs more timing and more idle airflow of a stock camshaft so the first thing I went in and changed was increased that base idle rpm setpoint and this is basically that the target that the ECM wants to shoot for and once the engine to idle at so because of that increased overlap of this aftermarket cam basically they don't idle as stable as a stock cam so you need to increase the speed that they're idling at and I kind of define a stable idle as being able to stick within that target set point plus or minus 50 rpm so that's why the first thing I did in that last video was went into this table and I added 225 rpm to every cell basically I wanted the slowest idle speed the ECM whatever command to be 750 and that's normally when the truck is operating engine coolant temp is while it's probably in the it's in this row here anyways so I wanted the lowest speed that the ECM would tell the truck to idle at to be 750 so next slide I'll tell you how I got that 750 number and it is basically from this table here which I believe came from somewhere on the HP tuners forum so I looked at my cam card it has an overlap of negative one degrees and so looking at this table here it's less than zero so that's why I went for a target idle rpm it says 750 to 850 but I went on the lower end of that basically the the ideal idle speed for any cam you want it to be the lowest rpm that it will be stable at like stay within that plus or minus 50 rpm like lower is better I don't totally agree with this timing part of the table I ended up with a lot more than an extra two degrees of timing but as you'll see later in the presentation I think I might actually screwed up and went a little too high on my bass Idol spark advanced tables but we'll tweak that when we hop on do some live tuning on the truck at the end of this presentation here so I also wanted to talk a little bit about how this ECM controls the idle and it's different on newer Chevy's newer Chevy's with the electronic throttle actually use that electronic throttle as your idle air control motor but since this is an older it's po1 or some people call it the old 4:11 computer basically it's got two ways of maintaining that target speed that we entered into that last table there's a the fastest way of controlling that idle speed is by adjusting the ignition timing and it does that based on the over speed and on our speed tables which we'll look at a little later in this presentation so if your actual idle rpm is less than the target like let's say from that table the ECM wants the engine to idle at 750 rpm if your actual idle is 700 it's going to increase that ignition timing to speed up the engine and if your idle rpm is more than the target let's say it's 800 it'll pull timing out to slow down the engine the other way of controlling the idle and so ignition timing is a fast-acting way of its reacts fast and it's a fast way of controlling the idle basically but there's another way that the ECM tweaks the idle speed and that is with the idle air controller and that's a slower way of a slower reacting way of controlling the idols and it opens and closes the idle air controller and like I said on newer vehicles that just open and closes the electronic throttle and that's basically like stepping on the gas a little bit with your foot it just lets a little more air into the throttle body and so to decide how far it opens that idle air controller motor the ECM looks at this base running air flow table and there's another table that uses in there that converts this g/s or desired air flow into idle air controller steps but I think you only need to change that if you're going with like an aftermarket throttle body so since I've got the stock throttle body that came with my 5.3 I left that idle air controller steps table alone but that's why I have to start at that last video I had to go in and adjust this table I adjusted most of the cells to 14 and that's basically like telling that idle air controller stepper to open the gas a little more it's like putting your foot on the gas pedal a bit to keep the truck idling better so then I went on to try and find the ideal idle timing and this is where I think I might have screwed up a bit so I locked in that idle air controller at a fixed I think it was 65 steps or something like that using that VCM controls and that basically fixes the throttle position at at one position otherwise I wouldn't be able to see the RPM change because if I bumped up the timing five degrees it would want to idle faster but the ECM would be stepping back on that idle air controller to try and maintain that setpoint so in order to find out what timing the engine likes to idle at I locked out that idle air controller at a set position so then I went in and adjusted the timing using those VCM controls to find the idle advanced setting or the the degrees of timing that give me the highest idle rpm and the highest manifold vacuum which is the lowest manifold air pressure reading so that basically is finding what degrees of advance of timing that that cam is most efficient at but I think now looking back and thinking about it I think I might have done this wrong because if I've set my base timing at the max rpm that that cam will run at then the ECM can't do its correction through the over speed and idle speed under speed idle tables because if it's calling for more speed it'll add more timing but the cams basically maxed out already so I think I might at the end of this video I'll go back in and adjust those base timing maps to around 25 degrees and that'll basically give the ECM a bit of room to work like if it's at 25 degrees of timing and idle speed is dropping it can still increase it up to 30 and increase the idle speed whereas if it's already running at 30 basically going from 25 to 30 is gonna have more of an effect on the timing or the idle speed then going from 30 to 35 so I think I'm gonna go back in and tweak that at the end of the video so then once I had found out the ideal idle spark advance I basically went into the spark advance tables for drive and park and that is basically the tables that the computer looks at one year idling and decides what to put in for timing and there are a couple other tables with engine coolant temperature and intake air temperature that put a multiply in there so if your coolant is getting hot or if the air coming into the engine is getting hot it will pull timing so that can change your idle spark events as well and again I'm thinking I went a little high initially like you can see I was at 30 degrees in the idle timing area so I'll probably go back and change that to 25 degrees on both in park and in gear tables then I went in and change that idle over speed and under speed tables and those are the tables that that computer looks at when it's controlling idle rpm with timing it looks at this table and says okay I want the engine to be idling at 750 rpm but it's actually at 850 I'm gonna pull six degrees of timing to slow it down so basically I reduce the amount of control by moving all the numbers over a couple cells and that's because you guys know when you put in a rowdy camshaft it it isn't a stable at idle so we basically want to give the cam a bit of room to wander without having the ECM trying to fight the natural kind of up-and-down changes of the cam so that's why we went in and modified those tables and then the last thing I did in that video was went back into that base running air flow and and I think yeah I think it's called the idle air flow table so initially I just plugged in 14 grams per second and that got the truck running without me having to pedal the gas but then we just went back in and did some final tweaks to that table and so that again that's the table that the computer looks at and decides basically how far to open the throttle which in this case is the idle air controller to keep the idle rpm at its target and so how you know you've got that number right is when the short-term idle trim and long-term idle trim are making minimal Corrections and so if either one of those are making big Corrections you got to go back and do a bit more fine-tuning of your air flow table there so ok guys I hope that she had a little bit of light or gave you a little bit of more information as to why I made the changes I made now I'm gonna fire up the laptop again and hop in the truck and I'm gonna change those bass I can't remember exactly what it's called now without having my computer in front of me but basically your bass idle spark tables I'm gonna change them from 30 to 25 and then I'll show you guys one other issue I was still having issues with the truck idling and drive and you can see it at the end of the last video the timing bouncing all over the place so I'll show you guys how I diagnose that and got rid of that so by the end of the video here we'll have the truck idling basically perfect perfectly hopefully so we'll fire up the computer view now and hop in the truck and do some final tweaks okay guys I got my scanner open here truck is running as you guys can hear I still haven't figured out how to get good audio when I'm recording and the truck is running so it sounds kind of crappy but so I just wanted to show you guys I went in and changed those bass spark advanced tables and idle in both parts and in gear tables 225 and you can see it's other than the occasional little correction it's at 25 but I just wanted to demonstrate the truck idles fine it's in park right now and you can see it's hanging in there it's the the computers calling for 800 rpm and it's pretty much staying within that plus or minus 50 tolerance that I'd like to see goes out of it every once in a little while but I can live with that but I wanted to show you it idles fine in park like it is right now you can hear it idles fine in Reverse we'll put it in Reverse right now and you can hear it idling fine it's still holding 25 degrees put it in neutral it idles fine still holding around that 25 degrees but what I want to show you is as soon as I shift into park the Idol goes to crap and you can see the computer pulling a bunch of timing so I'll show you that now I'm just shifting the park or our story to drive and you can hear the its idle and crappy and you can see that timing balance and like now it's in the negatives and it's bouncing all over the place and sounded like crap so and as soon as I switch back to neutral it takes a little bit for it catch itself but now we're back to twenty five degrees of timing so I wanted to figure out what is causing that causing the computer to pull all that timing as soon as I shift it into drive so I'm I'll just shut off the truck for a sec so I went in will stop scanning I won't stop scanning I made another channel configuration here this timing advance so basically I logged every parameter here that could either add timing or take away timing from the main spark table so we will I'll fire up the truck again we'll start recording here and then it'll be pretty clear which one of these is pulling all that timing and then we can go into the editor and fix what's causing that issue so I'll fire up the truck now and we'll demonstrate that we'll start scanning again so again I'm in Park everything's honey can see down here our cream idol trims our get long-term Idol trims our get and the longer it runs the the better these will get but that still looks basically perfect Idol timing is where where we want it to be at the table short-term and long-term Idol trims are are telling us our base airflow table is correct so idle in Park is perfect we'll switch to reverse for a second and you can see here our our airflow table is a little bit out yet because it's having to add about two grams per second so we could go back in and tweak that but it's still it's calling for it to be at 750 rpm like I can still totally live with that switch it to neutral that's fine now we'll switch to drive and now all of a sudden you can see our intake air advance is pulling some timing and our torque management in advance is pulling a bunch here so basically we're gonna go in oh now I can see that the coolant advance but it's this torque management one that's causing the main issue like there you can see it's it's blowing now let's not pulling any but now it's pulling 25 degrees at timing so I'm gonna shift back to park we'll shut the truck off or to make things stop dinging disconnect from here and so now I'm gonna go into the editor and we will disable that torque management and I think that's mainly what's been causing my my issues there's a little bit of timing being pulled because of that intake air temperature and engine coolant temperature but that's I don't want to mess with that because I I want it to do that if the truck gets hot or if it's sucking in hot air or whatever we want it to pull a bit of timing but it's that torque management that is what's causing my terrible idle in Drive so we're gonna go into torque management this versus rpm table and so this is no I don't think that isn't that isn't what I want or is it no it's right here this spark versus torque reduction pretty much looks the same but basically it when the computer is wanting to reduce the engine torque by 25% it pulls like 24 degrees of timing so I think that's what's happening so I'm basically gonna zero out this whole table I've selected it all for the 0 in that box make it equal 0 yeah you'll notice in that last video there's one time where I entered thirty degrees in the box or whatever but forgot to go over and click that equal sign so the table didn't actually change but now this tables actually changed will write it to the truck and I did notice on an initial startup it takes a five or ten seconds for the truck to kind of find its it's happy spot so there might be a little more tweaking that can be done there there's like a throttle cracker and startup airflow and throttle follower and a few other parameters that I haven't messed with yet but once the trucks been running for 10 or 15 seconds it goes to normal so we've wrote that to the truck now we'll go back to the scanner just got a text there that distracted me for a second so we'll connect start the truck again and yeah you can hear there it just kind of stumbles for 10 seconds or so but now it's pretty well back to normal so now we'll go in and try put it and drive again so that's in park that's in Reverse still does fine back to neutral it's doing fine and we'll try it park or in Drive keep getting my gears and it sounded way better like he can it's right at 25 degrees every once in a while that pulls a tiny bit of timing but it sounds a hundred percent better we could it looks like based on these short-term idle trims at our idle desired airflow we could go back to that base desired airflow table and increase it to about ten so I will probably I'll continue to tweak that you know as time goes on and all but you know it's sitting here in Drive idling it's maintaining that plus or minus fifty rpm pretty much so pretty happy with it so flip the camera round or go back to the camera mode here and talk to you guys for a second all right so I think that was the last piece of the puzzle that torque management table was messing up my idle in Drive there so we've got that working the way it should I may have to make a well I probably don't even have to but I probably will make a few final tweaks to that base air flow in gear table because it seemed to be wanting slightly more airflow but I'm pretty happy with it it's definitely drivable I can take it to the track take it to local cruise nights or whatever and I know it's not gonna stall when I come up to a stop sign or a park light and it's working pretty well so we're gonna wrap it up for this one thanks again for watching thanks for liking and subscribing and commenting thanks to Phyllis Tino for that question and we'll talk to you on the next one bye for now

Channel: Lowbuck LS

Views: 12,327

Rating: 4.9888268 out of 5

Keywords: hp tuners, idle tuning, hp tuners cam tuning, hp tuners torque management, hp tuners 101, ls idle tuning, ls turbo, ls turbo truck, turbo silverado, turbo silverado 5.3, turbo silverado build, hp tuners tutorial, sloppy mechanics hp tuners, efi tuning, how to tune, ls turbo cam, ls turbo build, turbo ls truck build, 5.3 ls turbo truck, vs racing, summit racing, summit racing cam, summit racing camshaft, gm efi, vs racing turbo, vs racing 7875

Id: Myi4GflrhNI

Length: 27min 18sec (1638 seconds)

Published: Sat Jun 01 2019