Idle, Throttle Follower, and Throttle Cracker

[Higgs Boson]

Ok I have searched around all day yesterday but could not find this info (which I am sure someone will link me directly to, lol).

I ran RussK Idle config for RAF and got the numbers very close. And it seems to idle well once fully warmed up. However, if I let it cool to say 160 or something other than 195, it won't idle well at all and surges/dies/etc upon startup and while driving. Also, when it is fully warm, if I start it to pull from driveway to garage and let the clutch out and quickly put it back in (since I am going 20 feet) it dies and coasts into the garage.

What do I need to do? Manually increase the values in RAF?


Also, when I log TCracker, what PID do I use? And TF? Is there a histogram I can use to edit these tables? I tried STFT but that did no good....

Thanks!

I have a ETC (so what do I do with IAC tables?), a 2001 Z06 OS converted to 1 bar MAF RTT, a 408 with 236/244@114 cam.

[69lt1bird]

Since it is doing this in Open Loop fueling because of the temp, have you tried adjusting the Open Loop F/A vs. Coolant Temp vs. MAP table in that range?

[Higgs Boson]

I have it set to 1.0 for all values 140-220 ECT (approx). Am I supposed to change that back to stock settings after tuning MAF/VE? Won't that mess up my PE? Also, at what temp does it go to CL? Is it not 93 degrees (in the CL enable table)?

[printmanjackson]

I have this same problem. is this something the throttle cracker can fix?

[Higgs Boson]

printman, mine only went away after I went speed density. i could never get my maf table right with my cam, or whatever was giving it fits. car is running, idling great now. good luck!

[printmanjackson]

thanks, I'll try that but I didn't think the MAF affected idle.

did you put the Open Loop F/A vs. Coolant Temp vs. MAP back to the original settings or leave it at 1

[S2H]

throttle follower and cracker are not used at idle...
follower is used when you have your foot on the gas pedal, cracker is used primarily when your foot is off the gas pedal...but is present when your foot is on the gas pedal
neither is used when the clutch is pressed in or when you are in "coast down" mode

cracker is best used to give you some cusion air when shifting to allow the rpm to fall at a controlled rate that will best match your shifting patterns to get it in the right rpm range for your upshift
you can remove or add air to it to control bucking when you let off the gas as well

follower is useful in when taking off from a stand still
you can add air or take away air from it to stop low throttle bucking

as soon as you push in the clutch, or go to coast down, they both decay to 0
if they dont reach 0, you dont enter idle and your adaptive idle parameters cant do their job.

typical reasons for your cold idle issues are usually not enough airflow at idle or improper Air Fuel Mixtures..
with a wideband, you can check A/F and you can adjust your OLFA(open loop Fuel air.coolant temp vs MAP) table so that your Air Fuel is close to stoic at those colder ECT's.
getting fuel correct is more important than having a correct RAF because RAF will learn and open loop fueling will not.

[S2H]

thanks, I'll try that but I didn't think the MAF affected idle.

did you put the Open Loop F/A vs. Coolant Temp vs. MAP back to the original settings or leave it at 1

MAF and VE values can affect idle...though it is mostly VE at idle unless your OS is 100% MAF

it typically is a blend and is controled by settings on the dynamic airflow tab

[Exidous]

After about two months of tinkering with the MAF and VE I have finally moved on to the Idle. I got my RAF close enough to where the STIT are under .5g/s off. Now my question is how does one get the PCM to catch properly. The car likes to die or nearly die as I push the clutch in and pull up to a light. It will do it if I rev the engine as well but not as bad.

[printmanjackson]

typical reasons for your cold idle issues are usually not enough airflow at idle or improper Air Fuel Mixtures..
with a wideband, you can check A/F and you can adjust your OLFA(open loop Fuel air.coolant temp vs MAP) table so that your Air Fuel is close to stoic at those colder ECT's.
getting fuel correct is more important than having a correct RAF because RAF will learn and open loop fueling will not.

is there a better way to tune other that using a WB? I have noticed my WB is not very accurate until the engine rune for a while. I don't think that will work well on a cold start.

[S2H]

buy a better wideband...

how do you know its not very accurate...what are you comparing it against?
you cant compare it against the narrowbands sensors that rely on exhaust heat to work properly...


when I do OLFA.. I usually temprorarily set the udle up to 1200~1500 ish in the tune so that I dont get the cam overlap short circuiting the Air fuel like it usualy does at idle...
gets you a more accurate reading for a cold start warm up to full temps.
then after I am done with OLFA, I set it back to my preferred idle settings
remember..you cant use AFR error for OLFA.. you have to make a custom PID for "Stoic Error"

[Frost]

throttle follower and cracker are not used at idle...
follower is used when you have your foot on the gas pedal, cracker is used primarily when your foot is off the gas pedal...but is present when your foot is on the gas pedal
neither is used when the clutch is pressed in or when you are in "coast down" mode

cracker is best used to give you some cusion air when shifting to allow the rpm to fall at a controlled rate that will best match your shifting patterns to get it in the right rpm range for your upshift
you can remove or add air to it to control bucking when you let off the gas as well

follower is useful in when taking off from a stand still
you can add air or take away air from it to stop low throttle bucking

as soon as you push in the clutch, or go to coast down, they both decay to 0
if they dont reach 0, you dont enter idle and your adaptive idle parameters cant do their job.
......

This isn't absolute though.. it is for some cars and OS's but certainly not all.

Many years of the F-body for instance, the throttle cracker IS active at clutch-in or off throttle for autos. I don't think I have ever seen a six speed vette though that the TC is active during clutch-in.

[S2H]

This isn't absolute though.. it is for some cars and OS's but certainly not all.

Many years of the F-body for instance, the throttle cracker IS active at clutch-in or off throttle for autos. I don't think I have ever seen a six speed vette though that the TC is active during clutch-in.

I've owned 3 fbodys... 99/00/01...and have never seen cracker when clutch gets pressed in...
as soon as you press in the clutch it decays to 0
unfortunately we dont have a table for decay time on the cracker, but we do for the follower

cant say 100% for certain on the auto's
but typically it decays to 0 when your torque converter unlocks for coastdown...

[Frost]

I've owned 3 fbodys... 99/00/01...and have never seen cracker when clutch gets pressed in...
as soon as you press in the clutch it decays to 0
.....

I'm just relating experience. Seeing a few dozen cars doesn't mean you've seen it all.

[Exidous]

I just got done toying with my cracker and follower. With changes to the follower I got noticeably better response and power starting out from a stop. Whereas with additional cracker on a H/C/I setup it kept the car from stalling after a WOT run when going to clutch in. As well as from a start up to say 5-10 MPH and then going 0% TPS and clutch in the car would die. Again cracker fixed this. I did not mess with decay at all but need to a tad.

[WS6FirebirdTA00]

This isn't absolute though.. it is for some cars and OS's but certainly not all.

Many years of the F-body for instance, the throttle cracker IS active at clutch-in or off throttle for autos. I don't think I have ever seen a six speed vette though that the TC is active during clutch-in.

Agreed. My car does not zero throttle cracker with the clutch pushed in.

[Frost]

This underscores one of the largest problems with online tuning discussions.

Lots of people are familiar with THEIR car and THEIR calibration and it's OS, and they forget that going + or - one year means that the answer is not always the same. This is particularly true for the airflow adders such as these, but stretches out much further.

[printmanjackson]

so what is the proper way to go about tunning and adjusting the throttle cracker and follower? I have built histograms for each and have logged data but what and how do you use this information?

the problems I have are falling idle sometimes and will not idle with AC on

[Exidous]

For the AC you need to look at the Adaptive Idle Airflow and add some air under the A/C on part. As for the Craker it was all trial and error for me. Can't give it too much or it will never come down and too little and it will still stall. Overall I ONLY needed to mess with the 400-2200RPM by 0-40 MPH to fix stalling at a light or maneuvering while parking. Follower was the same way. Just trial by error. Add more air if needed in fairly small increments until you get the desired results.

This is how I did it and probably not the right way but it did work for me. The car is still hard to start when heat soaked and will die easily due to the intake air temp not reading the right temp. Only thing wrong with the tune left that I can find. I guess i'll have to do the bias table. /sigh

[Frost]

For the AC you need to look at the Adaptive Idle Airflow and add some air under the A/C on part. As for the Craker it was all trial and error for me. Can't give it too much or it will never come down and too little and it will still stall. Overall I ONLY needed to mess with the 400-2200RPM by 0-40 MPH to fix stalling at a light or maneuvering while parking. Follower was the same way. Just trial by error. Add more air if needed in fairly small increments until you get the desired results.

This is how I did it and probably not the right way but it did work for me. The car is still hard to start when heat soaked and will die easily due to the intake air temp not reading the right temp. Only thing wrong with the tune left that I can find. I guess i'll have to do the bias table. /sigh

No just move your IAT out of the engine compartment so that it doesn't heat soak.