Gen4 idle tuning guide

[smallblock500]

@bigmike42 I have just started reading through some of this and did a quick scan through and did not see this but would you mind uploading the scanner layout that you used for this write up? I saw where michael_D posted a layout but not sure if its the same as what you used?

[BigMike42]

Sorry all, been busy with my new job. Shit hit the fan at prev company and I had to hunker down and find a new job before it was too late.

-I lost all my configs, really need to upload that shit to the cloud so that doesn't happen again . I am going to rebuild them with the 3.x scanner tomorrow. If I finish em up I will post. I am still not used to the 3.x scanner, I miss 2.x.

-Saw a post about blipping the throttle to set the idle airflow with all corrections turned off. Yes this is the correct way to do it. Everything has to be zero'd out. All airflow (prop/integral), all the costdown airflow follower tables, and the torque airflow follower tables. Don't forget to set high/low octane spark to your idle spark too since blipping the throttle sends you out of idle spark. I just save it as another tune so I can quickly go back once done.

First post is also a bit convoluted, sorry about that. It was a bit of a brain dump. I've relaxed my methods a bit. I still find base airflow using the same method (works great), but I'll see how the car runs with all stock settings first then adjust as needed. Most cars will be fine after finding base airflow if you just relax spark control a bit and move proportional up to around 100 rpm or so. My car still hates proportional, so I have to disable it, but newer cars may be fine with it left on. Mine idle hunts badly with it on coming to a stop.

Hopefully this thread has helped someone. Tuning a +15 overlap cammed C6 next week. Should be fun, owner wants to see if I can get rid of the catless cam smell LOL.

[schpenxel]

Tell him to add cats, catless smell eliminated!

[scottt28]

Good luck on new gig.

[BigMike42]

Tell him to add cats, catless smell eliminated!

Yep!

Good luck on new gig.

Thanks! It's going well so far.

Attached configs.

Cliffs:

Disable all airflow correction (prop and integral) + two follower sections, max adaptive idle msecs, zero out iat spark, set hi/lo spark to desired idle spark. Set base airflow to a number you think will be too high (it's much easier to adjust down, than up). Start car, blip throttle and pedal if necessary. Let idle settle for 5-10 secs. Once settled, start scanner. Shoot for average RPM error slightly positive and use that number. Keep adjusting the base idle air until you get this.

Set target idle cell to this value and 1 or 2 surrounding cells in each direction and blend the rest of the stock airflow settings in the higher rpms. Adjust higher rpm cells as needed if RPMs drop too fast when blipping throttle. Halve over/under speed, disable proportional airflow by maxing the RPM (you can try setting to 100 or 150 if you wanna try with it on). That should get most cars running smooth right off the bat. If 2008 car, disable the coastdown over/under correction, it makes no sense (they removed it in later year cars).

If the car idles well but still has trouble coasting or has other weird idle hunting issues, then you gotta start looking at throttle follower and integral tables. Adding to spark in higher idle and coastdown cells will slow rpm drop as well.

In the graphs config for rpm error, set the col axis first cell to whatever your target RPM is.

idle.Layout.xml
idle.Charts.xml
idle.Graphs.xml

[schpenxel]

Now those are some nice cliff notes that I'm going to try out soon

[ants-gts]

very big thank you for this thread i used this to dial my idle in today and what a difference

[BigMike42]

Now those are some nice cliff notes that I'm going to try out soon

Sweet. Once you get the hang of it you can find base air in about 5 mins. Im gonna use it on the kaotic cam this week.

very big thank you for this thread i used this to dial my idle in today and what a difference

Nice! Fairly big cam too. Glad this thread helped.

[scottt28]

Here's a draft version of the guide in Word. Might be a bit easier to read. Could be polished up and used as "handbook". Had to split into two files because initial edit was too big for file upload

[BigMike42]

Nice job Scott, you are responsible for it now

Probably would be better to have two sections: One for the base airflow + basic changes and then advanced stuff that deals with the integral and throttle follower tables, etc.

[BigMike42]

Tuned the 15 degree overlap cammed c6 just now. Manual car. Took 30 mins. Stick was way easier than even my small cam auto car. You just basically let spark correction do everything and push integral out as fail safe. Autos much harder IMO because the downshifts screw up everything.

The car was previously shop tuned. All they did was add random numbers to base air and startup airflow. I really need to start charging for this.

[mowton]

Idle and parking lot tuning are the two most difficult phases of tuning to accomplish. I found diving deep into how adaptive idle works was the best way to figure out how to tame the beast. Also, as Mike said, it takes time and many tuners just can't fit that into their bottom line....We have 43 pages dedicated to Adaptive idle :-o...Getting the airflow set to operate on its own is solid advice. Adding the "tempered" adaptive spark control back in at the end of the day to support will yield the most stable of idle platforms. Understand that the MAX/MAX Brake represent the most the blade needs to open (cold start), the Minimum Final Air is the least the blade needs to open and the PI works between those two to provide real-time and averaged error correction. Too much correction can be just as bad as too little when it comes to controlling idle. The spark will tell you how hard it is to maintain the desired idle rpm as far as too much or too little air and more importantly too much adaptive idle air control. nominal timing should hover around your base idle desired...any bias up or down requires airflow attention.

Have fun, take your time and picture the idle control process....you can tame the beast as well. And thanks Mike for all the time and effort you have put in in this informative thread.

Ed M

[scottt28]

It HAS TO BE worth a case of beer or a bottle of scotch.

[BigMike42]

Idle and parking lot tuning are the two most difficult phases of tuning to accomplish. I found diving deep into how adaptive idle works was the best way to figure out how to tame the beast. Also, as Mike said, it takes time and many tuners just can't fit that into their bottom line....We have 43 pages dedicated to Adaptive idle :-o...Getting the airflow set to operate on its own is solid advice. Adding the "tempered" adaptive spark control back in at the end of the day to support will yield the most stable of idle platforms. Understand that the MAX/MAX Brake represent the most the blade needs to open (cold start), the Minimum Final Air is the least the blade needs to open and the PI works between those two to provide real-time and averaged error correction. Too much correction can be just as bad as too little when it comes to controlling idle. The spark will tell you how hard it is to maintain the desired idle rpm as far as too much or too little air and more importantly too much adaptive idle air control. nominal timing should hover around your base idle desired...any bias up or down requires airflow attention.

Have fun, take your time and picture the idle control process....you can tame the beast as well. And thanks Mike for all the time and effort you have put in in this informative thread.

Ed M

Yes, both of our methods are spawned from the research Hymey did on the EFIlive forum (saw you post over there from way back)

I don't touch max idle area though, unless the cam is so radical, the stock setting needs to be increased. I use my base air as the target airflow, not the min, and calm the airflow adjustment way down. I've seen the correction bring TPS way below the base idle air TPS setting, so I don't think it's intention is to be a minimum airflow despite what the label says.

Different ways to skin a cat

[mowton]

Yes, both of our methods are spawned from the research Hymey did on the EFIlive forum (saw you post over there from way back)

I don't touch max idle area though, unless the cam is so radical, the stock setting needs to be increased. I use my base air as the target airflow, not the min, and calm the airflow adjustment way down. I've seen the correction bring TPS way below the base idle air TPS setting, so I don't think it's intention is to be a minimum airflow despite what the label says.

Different ways to skin a cat

Yes I have seen the same phenomenon...almost as if the idle controls are too tight they actual result in increased TPS%.....latest challenge was a MAST 246/260 on a 114 (25 degrees overlap) with insufficient CR. no more than like +/-2 degrees adaptive idle spark control....this one needed MAX/MAX Brake to increase to support cold start...idles like a baby...customer actually complained :-)

Ed M

[Brian P]

First off, thank you very much for the time put into this thread. It has been very helpful learning about the process to get the idle in check on gen 4 engines.

I'm running a 5.3L 2008 Trailblazer with DOD deleted. The cam is a Texas Speed Stage 2 low lift (spec card attached) which is promoted as a mild grind with "smooth idle". Anything off idle was decent off the bat, but idle has always been unstable, especially in park and neutral. This is a daily driver that I'm looking for the smoothest idle possible.

Originally when I first started tuning it (before finding this thread) I had increased the RPM to ~ 750, raised base airflow and had spark hovering in the 15-20 degree area. After following this thread, I found a better idle (or thought I did) with reduced airflow, and spark increased to 30 degrees. However, regardless of which direction I go, while the scan may look somewhat stable, the idle is choppy enough to shake the truck.

The proportional airflow control has been disabled, and this time around I'm running slightly modified versions of the integral, proportional airflow and spark under/over tables from a '13 Vette. I've used a lot of the tricks that have been discussed to tame much wilder cams, without much of a change on my end. I've gone thru the process several times and to me, I seem to be fighting a control that continues to cause the oscillations and shaking at idle.

I have attached my tune and the latest scan- the scan is brief, taken after 2 drive cycles of the tune upload. You'll notice that I used the controls at the end to bypass spark control and also raise idle, neither of which smoothens the idle. if anyone could lend their expertise on where else I could concentrate on the tune, it would be much appreciated.

[GHuggins]

Over / underspeed spark controls... Multiply by .5 - might even want to shift the tables to the right one cell before starting with the multiplication... Also highly recommend going back to a lower spark setting for idle - your going to wind up with stalling problems with it that high - your killing all of the spark reserve torque...

[Brian P]

Thanks, I'll try a ~ 22 degree idle and higher airflow. I was in that region at one point, but I had spark control way down- less than half of stock. I'm also going to try the airflow correction tables from a '13 5.3L Avalanche- they are way calmer than even my stock tables AFTER knocking them down.

[GHuggins]

I didn't see anything in the log pointing to throttle corrections, but something I don't think people on here are posting or realizing is that those "idle" airflow proportional and integral tables are in play even during throttle - best way to smooth out a bucking cam or jumpy take offs is to reduce the air adder portions of these tables while leaving the pullers close to stock flow... Only reduce the higher error areas a great amount... You can multiply the whole table by .5 then the higher error areas by another .8 - just enough to keep it transitioning to the same basic steps of the lower error areas... That helps a lot... Min air can go either way - more may be better because it keeps the egr effect minimized or less may be better - can't tell until you try both on the setup...

Big Mike knows lots more about this, so maybe he can chime in if he's able...

[Brian P]

So reduce the airflow correction on under RPM only? Attached is my latest scan. The timing correction is barely playing a role- I may tighten up timing correction and see what happens.